University Place Pedestrian...

University Place Pedestrian Overpass

Type, Size, and Location Study

August 2012 | Final Study Volume I of II

City of Spokane University Place Pedestrian Overpass i

Type, Size, and Location Study August 2012

Prepared for: City of Spokane 808 West Spokane Falls Boulevard Spokane, WA 99201

Prepared by: KPFF Consulting Engineers 1601 Fifth Avenue, Suite 1600 Seattle, WA 98101 (206) 622-5822 KPFF Job No. 110152.20

City of Spokane ii University Place Pedestrian Overpass

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Table of Contents 1. Executive Summary ....................................................................................................................... 1

Background ..................................................................................................................................... 1 Study Objective................................................................................................................................ 1 Recommended Alignment .............................................................................................................. 2 Recommended Approaches ........................................................................................................... 2 Recommended Bridge Type and Size ............................................................................................ 2 Estimated Construction Cost .......................................................................................................... 3

2. Introduction ................................................................................................................................... 4 Project Objectives ........................................................................................................................... 4 Project Scope of Work ..................................................................................................................... 4 Project Location and Existing Conditions ...................................................................................... 5

3. Project Design Criteria .................................................................................................................. 7 General ............................................................................................................................................ 7 Design Standards and References ................................................................................................ 7 Design Loads ................................................................................................................................... 8 Performance Parameters ............................................................................................................... 8 Bridge Features ............................................................................................................................... 9 Materials .......................................................................................................................................... 9 Health Impact Assessment ........................................................................................................... 10 Safety ............................................................................................................................................. 11 Railroad Parameters ..................................................................................................................... 11 Roadway Parameters .................................................................................................................... 12 Light Rail Parameter ..................................................................................................................... 12 Access Parameter ......................................................................................................................... 12 Bicycle Parameters ....................................................................................................................... 13

City of Spokane iv University Place Pedestrian Overpass

4. Environmental Documentation and Permitting ......................................................................... 14 Cultural Resources Assessment ................................................................................................... 14 Phase I Environmental Site Assessment ..................................................................................... 15 Local Agency Environmental Classification Summary ................................................................. 16

5. Geotechnical Analysis and Recommendations ........................................................................ 18 Geologic Mapping .......................................................................................................................... 18 Site History ..................................................................................................................................... 18 Subsurface Conditions .................................................................................................................. 18 Conclusions and Recommendations ............................................................................................ 22

6. Urban Design .............................................................................................................................. 23 Evolving Districts ........................................................................................................................... 23 Nodes and Connections ................................................................................................................ 30 Issues and Opportunities .............................................................................................................. 31 Urban Design Criteria .................................................................................................................... 32

7. Public Outreach .......................................................................................................................... 34 Stakeholders .................................................................................................................................. 34 Outreach Process .......................................................................................................................... 35 Project Blog .................................................................................................................................... 36 Surveys ........................................................................................................................................... 36 Open Houses ................................................................................................................................. 36 Traveling Display ........................................................................................................................... 38 Stakeholder Presentations ........................................................................................................... 38 Outreach Feedback ....................................................................................................................... 39

8. Trail Alignment Study ................................................................................................................. 42 General Connectivity ..................................................................................................................... 42 Alignment Alternatives .................................................................................................................. 42 Trail Alignment Recommendation ................................................................................................ 48

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9. Approach Landing Study ............................................................................................................ 50 Approach Landing Options ........................................................................................................... 50 Approach Height ............................................................................................................................ 50 Ramps versus Elevators ............................................................................................................... 50 Elevator Alternatives ..................................................................................................................... 51 Ramp Alternatives ......................................................................................................................... 53 Incorporating Green Space ........................................................................................................... 56

10. Landscaping ............................................................................................................................... 58 North Landing ................................................................................................................................ 58 South Landing ............................................................................................................................... 58

11. Bridge Type Study ...................................................................................................................... 60 General Bridge Types .................................................................................................................... 60 Length of Span .............................................................................................................................. 60 Depth of Superstructure ............................................................................................................... 60 Steel Trusses ................................................................................................................................. 61 Arch Style ....................................................................................................................................... 64 Cable-Stay Style ............................................................................................................................. 67 Bridge Type Selection Process and Recommendation ............................................................... 70

12. Electrical/Lighting ...................................................................................................................... 73 Codes and Standards ................................................................................................................... 73 Serviceability ................................................................................................................................. 73 Energy Conservation ..................................................................................................................... 74 Site Utilities .................................................................................................................................... 74 Electrical Power Distribution System ........................................................................................... 75 Lighting and Controls .................................................................................................................... 75

13. Right-of-Way Requirements ....................................................................................................... 77 WSU Riverpoint Campus ............................................................................................................... 77 Transit Corridor.............................................................................................................................. 77

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MLK Jr. Way ................................................................................................................................... 77 BNSF .............................................................................................................................................. 78 Southside Parcels .......................................................................................................................... 78

14. Storm Drainage .......................................................................................................................... 80 Existing Conditions ........................................................................................................................ 80 Proposed Storm Water Facilities .................................................................................................. 80

15. Utilities ........................................................................................................................................ 82 Sanitary Sewer ............................................................................................................................... 82 Potable Water ................................................................................................................................ 82 Overhead Utilities .......................................................................................................................... 82 Utilities on the Bridge .................................................................................................................... 82

16. Cost Estimate ............................................................................................................................. 83 Cost Ranges ................................................................................................................................... 83 Cost Estimate ................................................................................................................................ 84

17. Summary and Recommendations ............................................................................................. 94 Trail Alignment ............................................................................................................................... 95 Approach Landings ........................................................................................................................ 96 Bridge Type and Size ..................................................................................................................... 96 Cost Estimate ................................................................................................................................ 96 Next Steps ...................................................................................................................................... 98

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List of Figures

2-1 University District Boundaries ........................................................................................................ 6 3-1 Vertical Clearance Requirements ................................................................................................. 12 5-1 Boring Locations ........................................................................................................................... 19 6-1 University District Aerial (Unknown Date) .................................................................................... 23 6-2 University District Aerial (1967) ................................................................................................... 24 6-3 University District Aerial (Unknown Date) .................................................................................... 25 6-4 University District Aerial (1992) ................................................................................................... 26 6-5 University District Aerial (2002) ................................................................................................... 27 6-6 University District Aerial (2010) .................................................................................................... 28 6-7 University District Aerial (2011) .................................................................................................... 29 6-8 Connection to University District .................................................................................................. 31 7-1 Open House Participants Fill out Surveys and Comment Cards ................................................ 37 7-2 Logo for Open Houses ................................................................................................................... 37 7-3 Display at River Park Square Mall ................................................................................................ 38 8-1 Crossing Location Opportunities .................................................................................................. 42 8-2 Alignment A .................................................................................................................................... 43 8-3 Alignment B ................................................................................................................................... 44 8-4 Alignment C ................................................................................................................................... 45 8-5 Alignment D ................................................................................................................................... 46 8-6 Alignment E ................................................................................................................................... 47 8-7 Preferred Alignment ...................................................................................................................... 49 9-1 North Landing Scheme A .............................................................................................................. 51 9-2 North Landing Scheme B .............................................................................................................. 52 9-3 North Landing Scheme C .............................................................................................................. 53 9-4 Accessible Ramped Pathway with Landings ................................................................................ 53 9-5 North Landing Scheme D ............................................................................................................. 54 9-6 North Landing Scheme E .............................................................................................................. 55 9-7 Green Space Development ........................................................................................................... 56 9-8 Landing Options with Incorporated Green Space ........................................................................ 57 9-9 Landing Options with Incorporated Green Space ........................................................................ 57

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10-1 North Landing ................................................................................................................................ 59 10-2 South Landing ............................................................................................................................... 59 11-1 Triangle Truss ................................................................................................................................. 62 11-2 Canted Truss .................................................................................................................................. 63 11-3 Straight Arch .................................................................................................................................. 65 11-4 Curved Arch.................................................................................................................................... 66 11-5 Cable Stay Point............................................................................................................................. 68 11-6 Cable Stay Bow .............................................................................................................................. 69 11-7 3D Straight Cable Stayed Bow, Looking West .............................................................................. 71 11-8 3D Straight Cable Stayed Bow, Looking Southeast ..................................................................... 71 11-9 3D Straight Cable Stayed Bow, Looking Northwest ..................................................................... 72 12-1 Parcel Map ..................................................................................................................................... 79 16-1 General Cost Breakdown Limits ................................................................................................... 84 16-2 University Pedestrian Bridge Construction Fee Estimate ............................................................ 85 16-3 University Pedestrian Bridge Construction Fee Estimate ............................................................ 86 16-4 University Pedestrian Bridge Construction Fee Estimate ............................................................ 87 16-5 University Pedestrian Bridge Construction Fee Estimate ............................................................ 88 16-6 University Pedestrian Bridge Construction Fee Estimate ............................................................ 88 16-7 University Pedestrian Bridge Construction Fee Estimate ............................................................ 89 16-8 University Pedestrian Bridge Construction Fee Estimate ............................................................ 90 16-9 University Pedestrian Bridge Construction Fee Estimate ............................................................ 92 16-10 University Pedestrian Bridge Construction Fee Estimate ............................................................ 93 16-11 University Pedestrian Bridge Construction Fee Estimate ............................................................ 93 17-1 University Pedestrian Bridge Construction Fee Estimate ............................................................ 97

List of Tables

7-1 Alignment Survey Results ............................................................................................................. 40 7-2 Bridge Style Preliminary Survey Results (Open House No. 1) ..................................................... 40 7-3 Bridge Style Final Survey Results (Open House No. 2) ............................................................... 41

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Appendices (located in Volume II)

Appendix A – Cultural Resources Assessment Appendix B – Phase I Environmental Site Assessment (Complete document included on CD; report only

included in this printed version.) Appendix C – Local Agency Environmental Classification Summary Appendix D – Geotechnical Engineering Evaluation Appendix E – Site Electrical and Lighting Information Appendix F – Sole Source Aquifer Checklist and Map Appendix G – Site Layout and Bridge Details Appendix H – BNSF Conceptual Approval Documentation Appendix I – City Council Resolution Letter Appendix J – Health Impact Assessment

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City of Spokane University Place Pedestrian Overpass 1

1. Executive Summary BACKGROUND The University District is an emerging area targeted for new and re-development. The vision for the southern area of the district is to become a vibrant mixed-use area by providing housing and services for the college campuses to the north and for the Medical District on its southern border. This vision is emanating from the results and recommendations generated by many studies of the City of Spokane as well as the University District itself.

The report entitled, “America’s Next Great Academic Health Science Center,” by Tripp Umbach, studied the economic impact of the expansion of the Academic Health Science Center at Riverpoint over a 20-year period. The report estimates by 2030 the economic impact of an expanding center would “have a total annual regional economic impact of approximately $1.6 billion, support 9,276 jobs and generate more than $111 million in government revenue.” Opportunities generated by this type of growth include the need for transportation improvements and mixed use areas with affordable housing and commercial space.

These opportunities are tied to the need for connectivity within the University District. A barrier to the desired connectivity within the University District is the Burlington Northern Santa Fe (BNSF) railroad tracks along the southern boundary of the district. The BNSF corridor bisects the University District and separates the southern commercial and multi-use area from the northern institutional area of the district.

A new pedestrian bicycle bridge over the BNSF corridor is a critical missing link that has been identified and confirmed in many of the reports and has been described as a “key catalyst” in numerous studies over the years.

STUDY OBJECTIVE In August 2009, the City of Spokane (City) received federal funds to begin the process of defining the BNSF rail corridor pedestrian crossing. The funding source is the Transportation, Community, and System Preservation Program (TCSP). The TCSP program goals match very well with the University District vision for the pedestrian bicycle bridge.

The TCSP funds are being used to support this pedestrian bicycle bridge type, size, and location (TSL) study. The purpose of the TSL study is to identify what type of bridge should be constructed, what the spans and general geometry of the bridge need to be, and where the bridge should be located.

The TSL study included surveying, bridge type and size, project aesthetics, civil and structural engineering, geotechnical exploration, urban planning and design research, definition of permitting requirements, environmental engineering and public involvement to enable the bridge type, size, and location to be determined.

City of Spokane 2 University Place Pedestrian Overpass

The TSL process developed multiple alignments, landings and bridge alternatives. The selection of a preferred alternative was done using input from both the Mayor’s Advisory Committee and a public outreach program that included open houses, blogs, surveys, and traveling displays. The preferred alternative was advanced to a level that provided enough design to establish a preliminary project cost estimate. The estimate includes the costs for completing the bridge and landing design, purchasing needed rights-of-way, and construction of the project.

RECOMMENDED ALIGNMENT The preferred alignment ties Sherman Street with the intersection of the spine of the Riverpoint Campus and Main Avenue. The alignment’s southern approach starts at the intersection of Sprague Avenue and Sherman Street then travels up Sherman Street to the BNSF, Martin Luther King Jr. Way (MLK Jr. Way), and transit crossing. The pedestrian bicycle bridge then travels over the BNSF, MLK Jr. Way, and transit corridors; it then touches down at an intersection with the spine of the Riverpoint Campus and Main Avenue. See Chapter 8, Trail Alignment Study for more details.

RECOMMENDED APPROACHES Landing options that included both elevator and ramp configurations were developed. It was decided during the development of the landings that any approach height above approximately 25 feet created a ramp length (350 to 500 feet) that was simply too long. Consequently, any configuration requiring a height of this magnitude would use an elevator. Although the elevator options created the least footprint, the general public and the advisory committee all felt that elevators were the least desirable alternative.

Both structural and landform type ramps were studied. The preference was towards the more landform approach for the ramping design yielding a softer appearance than the highly structural concrete or steel ramping systems. See Chapter 9, Approach Landing Study and Chapter 10, Landscaping for more details.

RECOMMENDED BRIDGE TYPE AND SIZE For the University District bridge the foundations are required to remain outside the right-of-way for both the BNSF railroad and the new MLK Jr. Way. In addition, the bridge must remain outside a corridor north of MLK Jr. Way that is right-of-way for future mass transit. This meant that ends of the bridge are founded at the southern edge of the BNSF right-of-way and the northern edge of the future mass transit corridor. A single intermediate foundation is located between the BNSF and MLK Jr. Way rights-of-way. This creates a two-span bridge with spans of approximately 170 feet and 200 feet for a total bridge length of approximately 370 feet.

The key factor in the development of bridge alternatives was the desire to keep the superstructure depth as shallow as possible. This was due to the impact that the structural depth had to the overall ramp lengths and the required clearances over the BNSF/MLK Jr. Way/Transit corridors. A wide range of bridge styles were studied that were capable of spanning 200 feet while minimizing the superstructure depth including, truss, arch and cable-stayed bridges. Several straight and curved bridge styles were also studied. From the many bridge alternatives, there was a clear preference between the arch and cable-stayed styles. The cable-stayed bridge style was a two-to-one favorite


coming out of the public outreach process. In June of 2011, the City council adopted a resolution specifying the cable-stayed bridge as the alternative to move forward through the type, size and location study. See Chapter 11, Bridge Type Study for more details.

ESTIMATED CONSTRUCTION COST The preferred combination of alignment, landings and bridge type was advanced to a level that provided enough design to establish a preliminary project cost estimate range. The estimate includes the costs for completing the bridge and landing design, purchasing needed right-of-way and construction of the project.

The estimated cost range of the bridge per the findings of the TSL study is between $14 and $16 million.

The project costs will be affected by a number of variables. A few key variables include timing for project construction, and final geometry of the structure specifically the bridge width and actual ROW acquisition costs. See Chapter 16, Cost Estimate for further details.


2. Introduction The key economic development focus of the University District is to attract students, workers and businesses. In 2004, the University District Strategic Master Plan was completed with the support and involvement of many Spokane residents, community leaders and elected officials. A key finding of the Master Plan was the need to create connectivity for non-motorized users. The report stated, “The one mandate that came out of the public workshops, was to seek improvements for the pedestrian and bicyclist environment.” In fact, one of the key design principles of the University District is the support of a pedestrian/bicycle-based population.

PROJECT OBJECTIVES Two barriers to the desired connectivity within the University District are the BNSF railroad tracks and the new MLK Jr. Way, both of which are located along the southern boundary of the district. The BNSF/MLK Jr. Way corridor bisects the University District and separates the southern commercial and multi-use area from the northern institutional area of the district. The overall objective of this project is to develop a non-motorized connection from the Sprague area and medical district lying south of this corridor to the Riverpoint Campus academic facilities on the north.

The concept of constructing a pedestrian/bicycle bridge spanning the railroad tracks and connecting the East Sprague area to the University District campus emerged as a desired project noted as a “key catalyst” in the master plan. The bridge is intended to create not only a fundamental north-south link from the University District campus, on the north side of the railroad tracks, and the Sprague area and medical district on the south, but also a sense of place. Additionally, the bridge should support future mixed use development in the Sprague area.

PROJECT SCOPE OF WORK In August 2009, the City received federal funds to begin the process of defining the BNSF rail corridor pedestrian crossing. The funding source is the Transportation, Community and System Preservation Program (TCSP). The TCSP program goals match very well with the University District vision for the pedestrian bicycle bridge. The goals are as follows:

Improve the efficiency of the transportation system of the United States.

Reduce environmental impacts of transportation.

Reduce the need for costly future public infrastructure investments.

Ensure efficient access to jobs, services, and centers of trade.

Examine community development patterns and identify strategies to encourage private sector development patterns and investments that support these goals.

The TCSP funds are being used to support a pedestrian bicycle bridge type, size, and location (TSL) study. The purpose of the study is to identify what type of bridge should be constructed, what the spans and general geometry of the bridge needs to be, and where the bridge should be located.


The TSL Phase includes surveying, bridge type and size, project aesthetics, civil and structural engineering, geotechnical exploration, urban planning and design research, environmental documentation, definition of permitting requirements, and public involvement to enable the bridge type, size, and location to be determined. A mayor’s advisory committee was formed, which was comprised of individuals who understood and could represent the interests and concerns of both key stakeholders and the general public.

The TSL process developed multiple alignments, landings and bridge alternatives. The selection of a preferred alternative was done using input from both the Mayor's Advisory Committee and a public outreach program. In 2011, the Council approved the bridge type. The preferred alternative was advanced to a level that provided enough design to establish a preliminary project cost estimate. The estimate includes the costs for completing the bridge and landing design, purchasing needed right-of-way, and construction of the project.

PROJECT LOCATION AND EXISTING CONDITIONS The University District is located east of the city of Spokane’s downtown core. Its boundaries are Sharp Avenue to the north, Hamilton Street to the east, Interstate 90 to the south and Division Street to the west. The district is the center of the city’s higher education and includes Washington State University Spokane, Eastern Washington University, Gonzaga University, Whitworth University, and Community Colleges of Spokane.

Due to the potential for increased economic development resulting from improved higher education facilities within the University District, other neighborhoods in the surrounding area stand to be affected by changes within this district. Spokane’s Central Business District is located immediately to the west and presents a regional destination for businesses, entertainment, shopping and dining. To the south of Interstate 90 lies the Medical District, which is home to Sacred Heart and Deaconess Hospitals, as well as numerous clinics and support services to the healthcare industry. These two neighborhoods are expected to have some of the greatest impacts as the University District grows into a more robust hub for higher education.

The primarily residential neighborhood of Chief Garry Park can be found northeast of the University District, with pedestrian and bicycle access available to the University District via the two existing Spokane Falls Boulevard/Trent Avenue bridges. This neighborhood is expected to benefit from the addition of the proposed bridge as it would open up additional access for residents to cross south of the BNSF railroad tracks.

On the north bank of the river lies a patchwork of residential neighborhoods, with many commercial developments occupying space along Division Street to the western edge of the University District, and several manufacturing and industrial businesses located along the eastern edge near the Hamilton Street and Trent Avenue intersection. Further to the north on Hamilton Street, near the intersection of Sharp Avenue, the area has developed into a retail and commercial center for the neighborhood.

Lastly, the University District is also adjacent to a variety of transportation options. These options include major vehicle oriented arterials such as Interstate 90, Division Street, Trent Avenue, and Hamilton Street, as well as alternative transportation methods like the pedestrian and bicycle oriented Centennial Trail passing along the Spokane River.


Figure 2-1: University District Boundaries


3. Project Design Criteria GENERAL The primary goal of the University Place pedestrian overpass is to create a strong link between the Sprague area and the University District campus. The bridge and its approaches should provide safe and convenient access and support pedestrians, cyclists, and Americans with Disabilities Act (ADA)-accessible circulation. In addition, the bridge should serve as a visually welcoming and inviting icon for the area, connecting to existing and proposed destinations. It will also strengthen the current parks and trail system by linking with the Centennial Trail and other regional bicycle routes.

DESIGN STANDARDS AND REFERENCES The following is a list of publications utilized for the development of the type, size, and location of the proposed pedestrian bridge. They are listed in hierarchical order within the specific subheading with the most important appearing at the top of the list. This is not a comprehensive list; other applicable publications may be required to complete the design and construction.

Pedestrian Facilities Codes and References 1. Washington State Department of Transportation (WSDOT) – Pedestrian Facilities Guidebook,

Incorporating Pedestrians into Washington’s Transportation System, September 1997.

2. American Association of State Highway and Transportation Officials (AASHTO) – Guide for the Development of Bicycle Facilities, 1999.

3. WSDOT – Design Manual, December 2009.

4. AASHTO – A Policy on Geometric Design of Highways and Streets, 2004.

5. Institute of Transportation Engineers – Design and Safety of Pedestrian Facilities, March 1998.

6. American with Disabilities Act Accessibility Guidelines (ADAAG)

7. Draft Public Rights of Way Accessibility Guidelines (PROWAG)

Bridge and Structures Codes and References 1. Modifications for AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications to

Incorporate or Update the Guide Specifications for the Design of Pedestrian Bridges, January 2009.

2. AASHTO Guide Specifications for LRFD Seismic Bridge Design, 1st Edition, 2009.

3. AASHTO LRFD Bridge Design Specifications, Customary U.S. Units, 4th Edition, with 2008 Interim Revisions.

4. AASHTO LRFD Bridge Construction Specifications, 2nd Edition, with 2006, 2007, 2008, and 2009 Interims.


5. AASHTO – Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals, 4th Edition, with 2002, 2003, and 2006 Interims.

6. WSDOT – Bridge Design Manuals, Volumes 1 and 2, August 2002.

7. IBC – International Building Code, 2006 Edition, International Code Committee.

8. ACI 318 – Building Code Requirements for Structural Concrete, Reported by the American Concrete Institute Committee 318, 2005 Edition.

9. AISC 360 – Specification for Structural Steel Buildings, March 9, 2005, by the American Institute of Steel Construction, Inc.

10. Bridge Welding Code: AASHTO/AWS D1.5M/D1.5: 2008, An American National Standard, 5th Edition, with 2009 Interims.

11. Structural Welding Code – Steel: AASHTO/AWS D.1M/D1.1M, 2006.

12. ASCE 7: Minimum Design Loads for Buildings and Structures.

DESIGN LOADS

Dead Loads Typically included as self-weight.

Live Loads In addition to the live loads specified in the Modifications for AASHTO LRFD Bridge Design Specifications to Incorporate or Update the Guide Specifications for the Design of Pedestrian Bridges, January 2009, the following loads shall be included in the design:

Wind: Per code including the requirements to address aeroelastic instability

Snow: Per code

Ice: Per code

Vehicles: City-designated maintenance vehicle

Temperature Temperature Range: 0 to 120°F

Normal Installation: 64°F

Temperature Drop: 64°F

Temperature Rise: 56°F

PERFORMANCE PARAMETERS

Vibration Fundamental Frequency of Deck without Live Load f > 3.0 hertz


Structures not meeting the fundamental frequency criteria shall be designed utilizing the vibration criteria specified in the EuroCode or Ontario Highway Bridge Code.

Deflection Live Load Vertical Deflection < L/500

Wind Load Lateral Deflection < L/500

Span Length to Depth Ratio The effective span length to depth ratio of the bridge deck should be limited to 100.

Span Length to Width Ratio The bridge deck’s effective span to length to width ratio should not be greater than 30. The definition of the effective span of the bridge is the longest length between any two consecutive nodes of its fundamental vibration mode shape.

BRIDGE FEATURES

Bridge Railing The handrail shall be continuous and provide a barrier that prevents the passage of a 4-inch-diameter sphere from the finished grade to the top of handrail. The bridge railing shall meet the height requirements for bicycles.

Deck Joints Bicycle-safe expansion joints.

MATERIALS

Concrete - (Normal Weight) Precast Concrete Deck f’c = 5,000 pounds per square inch (psi)

Other Structural Concrete f’c = 4,000 psi

Other Non-Structural Concrete f’c = 4,000 psi

Reinforcing Steel Unless noted otherwise: ASTM – A615, Grade 60

Welded Rebar, Threaded Rebar: ASTM – A706, Grade 60 Low Alloy

Smooth Welded Wire Fabric: ASTM – A185, Fy = 65,000psi

Deformed Welded Wire Fabric: ASTM – A497, Fy = 70,000psi

Deformed Bar Anchors: ASTM – A496

Epoxy Coated Rebar: ASTM – A775

Structural Steel Steel Pipe Arches: API – API 5L X60

Other Pipes: ASTM – A500 – Grade B


Tubes: ASTM – A500 – Grade B

Bolts: ASTM – A325

Threaded Rods: ASTM – A36

Anchor Bolts in Concrete: ASTM – A307 (UNO)

Welding Electrodes: 70,000 psi Low Hydrogen Electrode

Headed Shear Studs: ASTM – A108

Structural Steel: ASTM – A36

Angles, Channels, Base Plates, and Miscellaneous Steel: ASTM – A36

Connection Material, Embedded Plates: ASTM – A36

HEALTH IMPACT ASSESSMENT The health impacts created by the pedestrian bicycle bridge were studied by a partnership between the City of Spokane and the Spokane Regional Health District. The study covered the health impacts on the current and future population living, working, studying and recreating within a quarter mile of the project. The results of the study are presented in a document called, “Spokane University District Pedestrian/Bicycle Bridge Health Impact Assessment (HIA).” The full report can be found in the Appendix.

The following six health impacts were studied:

• Physical Safety

• Physical Activity

• Perceived Safety

• Social Capital

• Economic Development

• Air Quality

Key recommendation coming out of the assessment relating to the six health impacts are as follows:

• Minimum of 20 lux lighting across the bridge and landing areas

• Lighting focused down on pathways

• Signage at crossings to alert traffic

• Traffic calming approaches at crosswalks

• Green space utilizing drought resistant flora and shade producing trees

• Visually appealing designs


SAFETY As stated in the HIA, perceived safety is an important aspect of the project design. It is important to make the bridge and pathways usable at night, providing adequate lighting along pathways and around seating areas. In addition to the lighting, emergency phones are needed similar to those provided on the Riverpoint Campus.

The HIA report also pointed out the need to provide on-going maintenance and clean up of vandalism in order to communicate to the users that the area is monitored. With this in mind, attention should be placed on the types of material used throughout the project. Materials should be easy to maintain and require minimal maintenance.

Physical safety was another impact studied in the HIA. The presence of the pedestrian bicycle bridge should increase the activity within the area of the project. The increased interaction between vehicles, cyclists and pedestrians will make the risk of personal injury an important consideration.

Appropriate signage is necessary in areas where pedestrians and cyclists intersect, including speed limits and yield-to-pedestrian areas. Consideration should be given to installing crosswalks in accordance with “Complete Street Standards.”

RAILROAD PARAMETERS

Permanent Vertical Clearance The minimum permanent vertical clearance, per Code of Federal Regulation, shall be 23 feet 4 inches, measured from the top of the highest rail to the lowest obstruction under the structure. The 23-foot-4-inch permanent vertical clearance must not be violated due to deflection of the superstructure. Additional vertical clearance may be required for items, including correction of sag in the track, construction requirements, and future track raise.

Permanent Horizontal Clearance All piers and abutments to be located outside the BNSF railroad right-of-way limits.

Fence with Barrier Rail Fence with barrier rail shall be provided on both sides of the pedestrian bridge crossing BNSF right-of-way. It shall be designed to prevent climbing and provide positive means of protecting the railroad facility and the safety of railroad employees below from objects being thrown by pedestrians or passing cyclists. The limits of the fence with barrier rail shall extend to the limits of the railroad right-of-way, or a minimum of 25 feet beyond the centerline of the outermost existing track, future track, or access road, whichever is greater. The minimum combined height of a barrier rail with curved fence shall be 8 feet or with a straight fence shall be 10 feet.

Drainage and Erosion Drainage from the pedestrian bridge shall be diverted away from the BNSF right-of-way at all times. Scuppers from the deck shall not be permitted to discharge runoff onto the track or access road areas at any time.


ROADWAY PARAMETERS

Vertical Clearance The minimum permanent vertical clearance shall be 17 feet 6 inches.

Figure 3-1: Vertical Clearance Requirements

LIGHT RAIL PARAMETER

Vertical Clearance The minimum permanent vertical clearance shall be as follows measured from the top of the highest rail to the lowest obstruction under the structure:

Preferred Minimum: 21 feet 6 inches

Desired Minimum: 15 feet 3 inches

Horizontal Clearance The minimum permanent horizontal clearance shall be 9 feet as measured from the center of rail to the nearest obstruction next to the tracks.

ACCESS PARAMETER

Maximum Vertical Grades 1:20 or five percent


Ramp Geometry Maximum 30-inch rise for 30-foot run

Cross Slopes Two percent maximum

Pathway Widths Multi-Use Path

10-foot minimum

12-foot desirable

14-foot optimal

Lighting 2.0 Footcandles or 20 lux minimum

Stairs Step width: 5-foot minimum

Step depth: 11 inches

Step rise: 7.5 inches

Tread to Rise Formula: 2R + T = 26 to 27 inches

BICYCLE PARAMETERS

Shared Use Path Minimum path width shall be between 10 – 14 feet depending on the expected usage.

Vertical Grades Grade versus Length of Run

Five to six percent for up to 800 feet

Seven percent for up to 400 feet

Eight percent for up to 300 feet

Nine percent for up to 200 feet

Ten percent for up to 100 feet

11 or more percent for up to 50 feet


4. Environmental Documentation and Permitting

Environmental documentation for the University District Pedestrian Bicycle bridge project included a cultural resources assessment, an initial Phase I Environmental Site Assessment (ESA) of property within the project alignment, and a WSDOT Local Agency Environmental Classification Summary (ECS).

CULTURAL RESOURCES ASSESSMENT The cultural resources assessment for the proposed project was conducted under prevailing Washington state laws, which serve to protect from known disturbance archaeological sites and Native American graves on both public and private lands. These laws include Executive Order 05-05, Indian Graves and Records (Revised Code of Washington [RCW] 27.44), Archaeological Sites and Resources (RCW 27.53), Archaeological Excavation and Removal Permit (Washington Administrative Code [WAC] 25-48), and Discovery of Human Remains (RCW 27.44).

Situated within Spokane’s University District and bisected by the BNSF tracks (formerly the Northern Pacific Railway), the project area was historically part of an industrial and commercial center, in contrast to the area west of Division Street where the primary business, financial, and hotel district is located. During the past 120 years or so, the greater project area has been extensively disturbed by excavation, filling, grading, and other landscape alterations connected with development. Within the University District, Gonzaga University was established on the north side of the river as early as 1887. Established in 1989 and 2007, WSU Spokane and EWU are more recent additions to the district south of the river. Industrial and commercial development has left the project area significantly altered.

Assessment Research and Investigations The objective of the assessment was to identify any previously recorded archaeological deposits from the prehistoric, ethno-historic, or historic periods that could potentially be present within the project areas. To determine if prehistoric or historic cultural resources were previously recorded within the project areas, a cultural resources literature search was performed at the Department of Archaeology and Historic Preservation (DAHP). The assessment involved review of design schematics and related project information, as well as background research. This assessment considered previous studies, the magnitude and nature of the undertaking, the nature and extent of potential effects on historic properties, and the likely nature and location of historic properties within the project area.

Three prior cultural resources investigations included portions of the project area; a fourth study was conducted immediately adjacent to the east. The Northern Pacific Railway grade (45SP499; now the BNSF) bisects the project area. No other cultural resources have been previously recorded within the project area and none were identified during the survey. Historically, the project area is within Spokane’s industrial and commercial center along the railroad tracks, and it is still characterized by industrial and commercial development. The construction of the railroad, buildings, roadways and


parking lots, including the extensive placement of a deep layer of fill in this area, would have severely disturbed soils and archaeological resources, if any, within the project area. The acreage field surveyed for the assessment comprises the maximum physical footprint of potential ground-disturbing activities associated with the proposed action. All softscape areas within the current project limits were examined for artifacts (e.g., flaked stone tools, tool-making debris, stone milling tools, fire-affected rock), soil discoloration that might indicate the presence of cultural midden, fire pits, soil depressions, and features indicative of the former presence of structures or buildings (e.g., postholes, foundations), or historic debris (e.g., metal, glass, ceramics). Ground disturbances, including dirt access roads and railroad grade, were visually inspected.

Findings and Recommendations No historic-era, ethno historic, or prehistoric resources were identified on the surface during the cultural resources field survey of the project area. The short segment of the Northern Pacfic Railway grade (45SP499; now BNSF) within the APE is considered not eligible for the National Register listing and therefore does not qualify as a historic property. Additionally, no historic properties will be affected. Considering the results of the literature search, local ethnographic settlement and subsistence patterns, the prehistory and history of the vicinity, the project area is considered highly sensitive for prehistoric, ethno historic and historic-era cultural resources. Due to the history of severe disturbance from industrial and commercial land-use to the entirety of the project area, the potential for discovery of buried archaeological materials, features, or deposits by implementation of this project is considered low. Therefore, no further cultural resource action is warranted. Complete Cultural Resources Assessment is included as Appendix A.

PHASE I ENVIRONMENTAL SITE ASSESSMENT The purpose of this Phase I Environmental Site Assessment (ESA) was to identify recognized environmental conditions (RECs) in connection with property within the project area. A total of 19 tax parcels are within the project boundaries. Existing data research, interviews, and field investigations were all conducted for the assessment.

GeoEngineers performed a Phase I ESA in general conformance with the scope and limitations of ASTM Practice E 1527-05 of the University District Pedestrian Bicycle Bridge project area located near the intersection of Riverside Avenue and Grant Street in Spokane, Washington. This assessment has revealed no evidence of RECs in connection with the subject property except for the following:

Approximately 5 cubic yards of fill material containing bricks and other debris was observed near the northern property boundary of the Judd property. The source and characteristics of the fill material is unknown and constitutes a REC to the subject property, in our opinion.

Exploratory test pits excavated near the south half of the WSU parking area (the subject property) during an environmental assessment, conducted by Landau in 2005, encountered lead-contaminated soil at concentrations greater than MTCA Method A unrestricted land use cleanup levels between 0 and 2 feet below ground surface. Lead-contaminated soil is a REC to the subject property, in our opinion.

Petroleum-contaminated soil from a UST excavation remains onsite at Ray’s Truck Service (727 East Pacific Avenue). Oil-range petroleum contamination was identified at a maximum concentration of 2,173 mg/kg. However, the sample location and depth was not identified. No


information regarding groundwater conditions is given in the Ecology file. Based on the upgradient location, residual oil-range contamination, and incomplete documentation, the site is considered a REC to the subject property, in our opinion.

Petroleum-contaminated soil and groundwater was identified at Bestway Trucking (also identified as Milne Trucking) associated with former USTs. Diesel-range petroleum hydrocarbons (DRPH) were detected at 25 ppm in groundwater samples collected from monitoring wells installed at the site, which is greater than MTCA cleanup levels. No additional reports of groundwater monitoring were available. Based on the impacts to groundwater and soil, the Bestway Trucking site is a REC to the subject property, in our opinion.

There is a moderate to high potential for soil and/or groundwater contamination from these conditions. Further evaluation of this potential will require additional research and/or explorations and testing of soil and/or groundwater. A Phase II ESA is recommended to further evaluate the RECs identified on the subject properties, specifically the Judd and WSU properties. Evaluating potential impacts to the subject properties from migration of contaminants through groundwater from off-site sources (Ray’s Truck Service and Bestway Trucking) will require, at a minimum, collecting groundwater samples from borings for chemical analysis.

Costs associated with remediation of potential contamination resulting from the identified RECs cannot be developed without additional data from Phase II ESA activities. However, based on the findings contained in this report and the nature of the RECs identified, remediation activities within the subject properties would be minimal, in our opinion. Additionally, remediation activities could likely be conducted during the earthwork portions of bridge construction. The complete Phase I ESA is included as Appendix B.

LOCAL AGENCY ENVIRONMENTAL CLASSIFICATION SUMMARY The project environmental classification determines the level of environmental documentation required for a project. Projects with federal funding are subject to the National Environmental Protection Act (NEPA) and the State Environmental Policy Act (SEPA). Because future funding is undetermined for this project, NEPA guidelines are being followed so the project can qualify for federal funding in the future.

Projects subject to NEPA fall into one of the three following classifications:

Class I Projects require preparation of an Environmental Impact Statement (EIS) because the action is likely to have significant adverse environmental impacts.

Class II Projects are Categorical Exclusions (CE) or Documented Categorical Exclusions (DCE). These actions are not likely to cause significant adverse environmental impacts.

Class III projects require preparation of an Environmental Assessment (EA) because the project’s impact on the environment is not clearly understood.

The University District Pedestrian Bicycle Bridge project has been classified in the NEPA process as a Class II – Categorically Excluded (CE) project. A determination of non-significance (DNS) has been recommended for the SEPA classification.


At this point, the only additional permits and/or approvals that may be needed are related to water quality requirements and the National Pollutant Discharge Elimination System (NPDES) Baseline General for Construction and requirements related to ROW acquisition.

Notable environmental considerations include the following:

The project is in an aquifer recharge area; consequently, a sole source aquifer checklist was included in the ECS documentation.

Regarding Essential Fish Habitat (EFH) and requirements for a Biological Assessment (BA), this project is designated as a “No Effect.”

The University District Pedestrian Bicycle Bridge project should have a positive effect on the surrounding environment due to the net reduction of pollutant generating pervious and impervious surfaces. The complete Local Agency Environmental Classification Summary is included as Appendix C.


5. Geotechnical Analysis and Recommendations

GEOLOGIC MAPPING Geologic mapping, completed by Derkey, Hamilton, and Stradling1, indicates that about the western half of the University District is located on a northwest-trending, basalt rock ridge. The basalt is classified as the Grande Ronde (Mgr) formation of the Columbia River Basalt Group. Grande Ronde Basalt typically consists of dark gray, fine-grained basalt of irregular thickness. In the eastern half of the University District, north of the Spokane River, the basalt ridge is overlain by Holocene age Alluvium characterized as reworked glacial flood deposits including silt, sand and gravel deposits. To the south of the Spokane River, the eastern boundary of the University District is underlain by glacial flood-channel deposits, predominantly gravel (Pleistocene), which are described as thick-bedded to massive mixture of boulders, cobbles, gravel, and sand that fill deep, ancestral channels of the Spokane and Little Spokane Rivers. These deposits now form the Spokane Valley-Rathdrum Prairie aquifer.

SITE HISTORY The Riverpoint Campus, East Sprague Corridor, and surrounding area retain little of their original geologic surface characteristics, due to past development. One such development was the construction of rail yards on the Riverpoint Campus. To develop a relatively level site, it appears that some of the rocky outcrops were leveled and low areas were filled with rock rubble. Other areas appear to have been filled with local gravelly soils or debris. From the presence of ash, melted glass, brick, metal and other debris identified in previous geotechnical and environmental reports completed on the Riverpoint Campus, it appears that some of the site fills probably were derived from rubble associated with the Spokane fire of 1889.

SUBSURFACE CONDITIONS

Field Explorations and Laboratory Testing Subsurface conditions at the site were explored on September 11, 12, and 28 of 2011, by drilling seven borings (N-1 through N-3, P-1, and S-1 through S-3) at the approximate locations shown on Figure 5-1. Borings N-1 through N-3 were drilled at the North Abutment, P-1 was drilled at the approximate location of the Center Pier, and S-1 through S-3 were drilled at the South Abutment. The borings were advanced to depths in the range of about 14 to 33 1/2 feet below existing ground surface using a truck-mounted CME 75 hollow-stem auger drill rig with NQ rock core attachment, owned and operated by GeoEngineers. Representative soil and rock samples from the explorations were returned to our laboratory for examination and testing. Detailed descriptions of our site exploration and laboratory testing programs along with exploration logs and laboratory test results are in the full report, included as Appendix D. 1 Derkley, Hamilton, and Stradling, “Geologic Map of the Spokane Northwest 7.5-minute Quadrangle, Spokane County,

Washington.” Washington Division of Geology and Earth Resources Open File Report 2004-3.


Figure 5-1: Boring Locations




Soil and Rock Conditions Below the existing topsoil and pavement, a variable subsurface condition exists. The variable conditions included soil and rock that can be classified in the following two general units:

Overburden soil

Basalt rock

Overburden Soil The overburden soil is classified as generally consisting of silt, silty gravel and silty sand with variable cobble and boulder content. Near the north abutment and associated ramp (borings N-1, N-2, and N-3), the overburden soil generally consists of medium stiff to hard silt and loose to very dense silty gravel to depths in the range of about 3 1/2 to 9 1/2 feet below current site grades. The thickness of the overburden soil generally increased towards the north. Near the center pier location (boring P-1), medium dense silty sand and gravel extended to about 3 feet below current site grade.

Near the south abutment and associated ramp (borings S-1, S-2, and S-3), silt, silty sand, silty gravel and apparent cobbles and boulders extended to depths in the range of about 2 1/2 to 17 1/2 feet below current site grade. At boring S-1, near the south abutment and adjacent to a northern-facing bluff, approximately 17 1/2 feet of overburden soil overlies basalt rock. Based on the variable soil conditions, site and surrounding topography, the overburden soil in and around boring S-1 likely consists of reworked indigenous soil or possible fill.

Basalt Rock Basalt rock of variable quality and consistency exists below the overburden soil unit in each boring. Coring took place about 9 1/2 to 15 feet into the rock, to depths of about 14 to 33 1/2 feet below ground surface in the borings. The rock core recovered from the borings is moderately to highly fractured, predominantly vesicular basalt, as described on the boring logs in Appendix D.

Depth to rock near the north abutment ranged between about 3 1/2 to 9 1/2 feet below current site grades (depth to rock generally increased towards the north). Rock quality designation (RQD) of the rock core in borings N-1 through N-3 ranged from 44 percent to about 95 percent. The RQD is a qualitative measurement of the competency of the rock, as described in Appendix D.

Rock at the center pier is located at about 3 feet below current site grade at boring P-1. The RQD ranged from about 83 to about 93 percent.

Depth to rock near the south abutment was more variable than at the north abutment and center pier, ranging from 2 1/2 to 17 1/2 feet below ground surface. The quality of the rock also was more variable than at the northern explorations with weathered rock in boring S-3, starting at about 2 1/2 feet below current site grade and gradually transitioning to unweathered basalt at about 11 feet. The RQD of rock encountered near the south abutment, typically ranged from about 35 percent to 100 percent, but in weathered areas at the ramp area (boring S-3), an RQD of 0 was observed.

Groundwater Conditions Groundwater was not encountered within the depths explored at the locations of the borings. Because of the rock coring method used, monitoring groundwater levels following completion of rock coring


activities was not possible. The regional groundwater table likely is several tens of feet below current site grade. However, perched groundwater will likely be present at the interface between overburden soil and basalt rock, and within the weathered and fractured basalt. The locations and depths at which perched groundwater occurs will fluctuate seasonally and depend on factors such as precipitation and local drainage features.

CONCLUSIONS AND RECOMMENDATIONS Based on the results of the geotechnical engineering evaluation, the development of the proposed University District Pedestrian Bicycle Bridge is feasible with respect to subsurface conditions encountered in the project area. Based on the soil conditions observed during the field exploration program, spread footings are the most economical option. However, adjacent to the railroad tracks and MLK Jr. Way, excavations for spread footings may not be feasible due to space constraints. Because spread footings cannot be constructed adjacent to the tracks and roadway, drilled shafts appear to be the next best option as a consequence of shallow rock. The complete geotechnical report is included as Appendix D.

Other key geotechnical considerations for the project include:

The north and south abutments may be supported by shallow foundations bearing on the basalt rock. It is expected that excavations required to expose basalt at the north abutment will be in the range of about 3 to 10 feet below current site grade. At the south abutment, it is anticipated that excavations required to expose basalt will be on the order of about 16 to 19 feet below current site grade. Additional excavation might be required to remove weathered rock. Cobbles and boulders should be expected within the overburden soil.

Drilled shafts embedded in basalt rock or shallow foundations bearing on basalt rock may be used at the center pier. It is expected that excavations required to expose basalt at the center pier will be on the order of 3 feet below current site grade.

Associated pedestrian ramp retaining walls also should extend to and bear on basalt rock to reduce potential differential settlement that could be associated with the variable wall heights and fill thicknesses.

The regional groundwater table is not expected to be encountered during construction. However, perched groundwater could be present depending on the time of year construction is undertaken and nearby irrigation activities.

The fill and overburden soil units may be excavated using conventional earthmoving equipment that is capable of removing cobbles, boulders and miscellaneous construction debris at the site if present as a consequence of demolition activities. Drilling and pneumatic hammers might be required to adequately prepare basalt rock for shallow foundations at the north and south abutments. Because of adjacent facilities including BNSF rail lines, blasting will not be allowed at the site.


6. Urban Design EVOLVING DISTRICTS The University District is an emerging area targeted for new and re-development. The vision for the southern area of the district is to become a vibrant mixed-use area by providing housing and services for the college campuses to the north and for the Medical District on its southern border.

The evolution of the University District is visually depicted in the following series of aerial photographs.

Figure 6-1: University District Aerial (Unknown Date)


Figure 6-2: University District Aerial (1967)


Figure 6-3: University District Aerial (Unknown Date)









The evolution of the University District has been studied in many reports. The report entitled, “America’s Next Great Academic Health Science Center,” by Tripp Umbach, studied the economic impact of the expansion of the Academic Health Science Center at Riverpoint over a 20-year period. The report estimates by 2030 the economic impact of the district, after having reached full expansion, would generate “approximately $1.6 billion [annually], support 9,276 jobs and generate more than $111 million in government revenue.”

The pedestrian bicycle bridge has also been included in of the following planning studies and reports including:

The University District Strategic Master Plan (2004)

The East Central Neighborhood Plan (2006)

Policy Options for a New Urban Center (2006)

Fast Forward Spokane Downtown Plan Update (2008)

University District Targeted Area Development Report (2008)

University District/Downtown Spokane Transportation Improvement Plan (2008)

Riverpoint Campus Master Plan Update (2009)

University District Housing Study (2009)


University District Revitalization Area (2009)

Bike Master Plan (2009)

Smart Routes Case Statement Active Transportation Campaign (2010)

Spokane Economic Development Portfolio (2010)

University District-Sprague Corridor Plan (2011)

Opportunities generated by this type of growth include the need for things such as transportation improvements and mixed use areas with affordable housing and commercial space. These opportunities are tied to the need for the connectivity provided by the pedestrian bicycle bridge.

A new pedestrian bicycle bridge is a critical missing link that has been identified and confirmed in many of these reports and has been described as a “key catalyst” in numerous studies over the years.

NODES AND CONNECTIONS The Riverpoint Campus has recently undergone a master plan that envisions growing into an urban campus, well connected to housing, services, cultural activities and jobs and relying less on the single occupant commuting that currently exists today. The physical plan for the campus is to organize its buildings around an established central spine that provides a contiguous pedestrian connection and open space through the central core of the campus. Additionally, the Spokane Transit Authority (STA) has included a connection to the Riverpoint Campus spine in its plan for the future City Central Line.

Within the district there are important landmarks, nodes, and connections, both existing and planned, that bring together a variety of activities and users. Running east-west through the center of the district is the very active BNSF rail line that, with its heavy train traffic, acts as a barrier between the campus and South University District. While this rail line is a physical barrier for cars, pedestrians, and bicycles, it does bear significant historic and economic importance to the City.

The new MLK Jr. Way on the north side of the BNSF right-of-way will act as a major east-west transit corridor providing multi-modal access to downtown, across the Spokane River, and beyond. It will also serve as a new entrance to the Riverpoint Campus. Officials from the Spokane Transit Authority and the Spokane Regional Transportation Council have identified the bridge landings as a possible location for future bus transfer facilities. Main Avenue, Spokane Falls Boulevard, and the Centennial Trail are all part of the bicycle network connecting the campuses (both Gonzaga and Riverpoint) to downtown and beyond. Sherman Street is a designated bicycle route off the South Hill and one of the crossings over Interstate 90 to the Medical District. It is uniquely positioned to facilitate pedestrian and bicycle traffic into the Riverpoint Campus as well as downtown.

The Sprague Avenue Corridor, roughly two blocks south of the BNSF line, already serves as a major auto-oriented connector to downtown, but it has recently undergone a study to redesign it as a complete street, which will improve its usability for pedestrians. Additionally, this improvement corridor has been identified to receive more short and mid-term infill commercial and residential opportunities.


Figure 6-8: Connection to University District

ISSUES AND OPPORTUNITIES The location and style of bridge have an opportunity to help identify and shape the district as it may become a center piece of the overall bicycle and pedestrian network. There are many transportation related upgrades that are helping to complete the network in this area. The critical link remains the crossing of the BNSF rail line. Evaluating the locations and alignments for the bridge landings took into consideration all these linkages as well as integration with the existing neighborhood grid pattern and the impact the connections will have on the property, residents and business owners.

A signature pedestrian and bicycle bridge has the opportunity to highlight the district by creating a place-making icon, both from the up close experience and from a distance. This has been demonstrated in many communities across the country, such as Denver and Portland; while it is difficult to make a direct link to the economic impact of the bridge itself, these examples demonstrates how a signature bridge can be one of the early drivers in the development of an area into a vibrant neighborhood.

In early discussions with the Mayor’s Advisory Committee, a set of urban design criteria was established to identify the major opportunities the bridge could address. The criteria were then used in the evaluation of the various alignment and bridge alternatives.


URBAN DESIGN CRITERIA

Connectivity 1. The bridge is part of a network of walkways, trails, and sidewalks that allow people to walk and

bicycle throughout the district in multiple directions.

2. The bridge is a critical connection across a major transportation barrier, allowing the higher education functions and recreational amenities on the north to interact with commercial and living spaces on the south.

3. Because it is the only such connection within the district, its location and use should be prominent.

Clarity 1. As redevelopment around the bridge occurs, there is the potential for it to be visually obscured.

But because its role is so important, its form should not recede into the background, but be distinctive and highly visible.

2. The bridge serves as a symbol for co-joining the academic and the urban communities.

3. This symbolic role is significant enough to suggest a scale and form that is amplified beyond the basic functional and structural requirements.

Character 1. The bridge will have multiple identities. It should be visible from a distance – as much as several

blocks away. Like many other bridges throughout the world, the bridge should be a landmark that allows for people to be oriented to where they are within the city and the district.

2. The bridge should be seen by the public not merely as a corridor to be used to get between two points, but as a unique and exhilarating experience.

3. The bridge could be a unique destination, much like a number of other places in downtown.

4. The approaches to the bridge should include trees and other vegetation to enhance the experience.

Comfort 1. The bridge will accommodate a wide range of users – walkers who are commuters, walkers who

are on a leisurely stroll, people who are disabled, and people who are using bicycles. The bridge will be used by people of all different ages and types.

2. Because of the clearance over the tracks, its height will likely require special means – structural and/or mechanical – to convey people up and down vertically.

3. The bridge should offer a high degree of comfort for people in a number of different ways: convenient access, personal safety, some degree of shelter from wind, rain and snow, dry non-slip surfaces, and a general sense that the experience of traversing it is pleasant.


Catalyst 1. As a distinct piece of architectural engineering, the bridge can energize its surroundings with a

new image and value.

2. Private investment can be stimulated and enhanced through creating an ambiance that includes the bridges, attractive approaches and streetscapes, landscaping and public spaces.

3. Because the existing context within the University District is evolving, the bridge can convey both stability and vitality. A particularly distinctive bridge could attract people to live in a unique and transforming neighborhood.

4. The bridge and its associated connections can serve as a demonstration of more sustainable methods of circulation in the district and downtown.


7. Public Outreach Stakeholder outreach and public involvement were integral parts of the TSL study process. Considerable effort was made in presenting options and gathering feedback from Stakeholders and the public throughout the study process.

A major component of the stakeholder outreach was the formation of the Mayor’s Advisory Committee. The Mayor’s Advisory Committee was comprised of individuals who understood and could represent the interests and concerns of both key stakeholders and the general public. Organizations and interests represented included the following:

University District Board Director

University District Advisory Council

Washington State University

Spokane Transit Authority

Bike perspective

City of Spokane – Economic Development

City of Spokane – Capital Programs

Input from the Mayor’s Advisory Committee was solicited in a series of seven workshops. The committee reviewed and contributed to the project design criteria, alignment alternatives, bridge styles and landing configurations. As information was collected from the overall public outreach process, the committee analyzed the data and provided feedback to the design team.

STAKEHOLDERS Outreach was broad and included, but was not limited to, the following stakeholders:

Elected officials and public offices Spokane Mayor

Spokane City Council

Spokane County

Spokane Public Works Committee

Spokane Regional Health District

Adjacent Property Owners Approximately 25 key property owners were located within an area bound by South Cowley Street to the west, East Riverside Avenue to the north, North Sheridan Street to the west, and East Sprague Avenue to the south.


University District Organizations SIRTI

University District Board

Avista

Neighborhood Groups East Sprague

International District

Logan

Riverside

Academic Organizations Washington State University

Gonzaga University

Eastern Washington University

Whitworth University

Spokane Community Colleges

Special Interest Organizations Friends of the Centennial Trail

Friends of the Falls

East Sprague Business Association

Downtown Spokane Partnership

Greater Spokane Incorporated

Spokane Regional Health District

OUTREACH PROCESS A variety of methods to provide information and gather feedback from the public were utilized. General information was shared through the following avenues:

Postcards

Informational fliers

Project blog and other websites

Articles in interest group newsletters

Reports to elected officials and medical and academic leadership

Traveling display

Open houses


Feedback was gathered through the following methods:

Surveys on the project blog

Surveys handed out at presentations, open houses and along with the traveling display

Written and verbal comments at the open houses

Feedback was reported back to the stakeholders and the public in the following ways:

Reports to leadership groups

Articles in newsletters

Website

Follow-up open house

PROJECT BLOG The blog was developed and maintained as a low-cost way to provide information to key stakeholders and general public. It received over 6,200 non-project team hits during the study process. The blog was advertised on all project materials (including 6,000 postcards distributed in the project area), through the media and City, and with links from key stakeholders, such as WSU and Gonzaga, the University District, and community groups.

SURVEYS A link to a survey was placed on the blog to capture the preferences, issues, and concerns of the public after they viewed the project information on the blog. Survey results were carefully studied by the committee and consultant team.

OPEN HOUSES Two open house events were conducted (Oct. 2010 and March 2011) to provide information and gather feedback. Post cards mailed to 4,054 addresses closest to the project site; another 2,000 post cards handed out on campuses and to local property owners. To increase participation and save money, the team combined with the Central City Mobility community outreach: the response from the public was great.


Figure 7-1: Open House Participants Fill Out Surveys and Comment Cards

Figure 7-2: Logo for Open Houses


TRAVELING DISPLAY A traveling display was created to provide information about the project. It included survey forms to gather information from those visiting the display. The display traveled to many locations including the River Park Square Mall and throughout the University District. It was also provided for gatherings such as the University District Kick-Off Reception and Catalyst Awards, and the Greater Spokane Incorporated’s Good Morning Spokane.

Figure 7-3: Display at River Park Square Mall

STAKEHOLDER PRESENTATIONS In addition to the project blog, surveys, and open houses, periodic updates were provided to key stakeholders, including the following:

University District Board

City of Spokane Public Works Committee

Spokane’s Plan Community Economic Development Board

City of Spokane Plan Commission

Bicycle Advisory Group

Greater Spokane Incorporated

Property owners

Gonzaga and WSU student leadership

Spokane Regional Transportation Council


Downtown Spokane Partnership

Logan Neighborhood Council

OUTREACH FEEDBACK At key decision points throughout the study, feedback was sought from the stakeholders and general public. There were two major methods for the stakeholders and general public to provide their feedback. One was through attending one of the two open houses and filling out a comment card. The other was responding to the project surveys that were available in a wide variety of locations. The comment cards generated hundreds of responses and the blog was very successful with over 6,000 hits and hundreds of responses to the online survey.

There were two key decision points during the study. The first was formulating the pathway alignment and the associated approach landing configurations. The second was determining the bridge type. Each of these topics will be discussed in detail within their associated sections in the study. The specific sections will include how the feedback was incorporated into the decision-making process; consequently, only a brief overview of the feedback will be provided within this section.

Decision Point No. 1 – Trail Alignment and Approach Configuration The objective of the first open house and the first survey was to collect feedback on the possible trail alignments and approach configurations. Two alignments and their associated approach landings were presented for comment. Each alignment and approach landing was presented visually. In addition, the attributes as well as the comparative differences of each alternative were outline and summarized.

Option 1 was an alignment that crossed the BNSF right-of-way perpendicularly at Grant Street. The Option 1 alignment is described in Section 7 under Alignment A. Option 2 was an alignment that crossed the BNSF right-of-way at an angle from Sherman Street. The Option 2 alignment is described in Section 7 under Alignment B.

Key take away points from the survey were the preference to not have an elevator at either landing, incorporating green space is important, and the height and length of the pathway should be minimized.

The alignment alternatives were refined to reflect the public input. During the second open house and survey, feedback was solicited on how well comments had been incorporated.

Alignment survey results are shown in Table 7-1.


Table 7-1: Alignment Survey Results Question: Please indicate your preference of the two options below.

Answer Options Response Percent

I prefer Option 1 24.9%

I prefer Option 2 75.1%

Decision Point No. 2 – Bridge Type The objective of the second open house and the second survey was to collect feedback on the possible bridge styles. In order to get preliminary feedback, three bridge types were briefly presented in the first round of surveys. The top two preferred bridge types were then refined and presented at the second open house and within the second survey. Each bridge style was presented visually in 3-dimensional renderings and an animated flythrough. In addition, the attributes as well as the comparative differences of each alternative were outline and summarized. The various bridge alternatives are described in Section 11.

Key take-away points from their survey were the height of the cable-stay bridge providing a focal point and the low profile of the arch style getting lost in the surrounding structures.

See Table 7-2 and 7-3.

Table 7-2: Bridge Style Preliminary Survey Results (Open House No. 1) Question: Which bridge style do you prefer?


Truss 24.4%

One arch 39.3%

Cable stay 36.3%


Table 7-3: Bridge Style Final Survey Results (Open House No. 2) Question: Which bridge style do you prefer?


Cable-Stayed 64%

Arch 36%


8. Trail Alignment Study GENERAL CONNECTIVITY

Figure 8-1: Crossing Location Opportunities

ALIGNMENT ALTERNATIVES While studying the possible trail alignments the following key design elements were identified:

To facilitate a safe pedestrian route from the south, the alignment should utilize the signalized intersection at the Sherman Street crossing of Sprague Avenue.

Sherman Street is also part of a bike corridor extending south of Interstate 90.

To address the lack of green space to the south of the BNSF corridor, redevelop the property adjacent to the south landing as a park and/or open space amenity integral with the approach ramp.

Minimize the height and footprint of the northern approach landing.

The north approach should line up with the WSU Riverpoint Campus central promenade.


The design team brainstormed a wide variety of alignment alternatives. These alternatives were refined down to five alignments for further study. The alternatives are labeled Alignment A through Alignment E and are described below.

Alignment A This alignment launches from Grant Street and crosses directly to the campus node defined by the intersection of pathways from the campus central spine or mall and Main Avenue. The objective of this alternative was to minimize the structure length and property acquisition requirements. Alignment A draws pedestrians through Grant Street which dead ends on the south side of Sprague Avenue, not directly linking in the existing bicycle network. In addition, this pathway does not provide a safe access for pedestrians to cross Sprague Avenue as there is no signalized intersection at Grant Street.

The bridge would be at a height of 26 feet above the existing ground on the Riverpoint Campus side. This would require a ramp for ADA access that is approximately 370 feet in length. The disadvantage of this is the lack of space for the large area needed for the ramp and the long distance needed to be traveled for those that could not use a more direct stairway system. An elevator would be another alternative to bring pedestrians down the 26-foot height. The disadvantages to an elevator are the ongoing maintenance costs related to operations of an elevator and the potential safety and security issues associated with riding an elevator.

Figure 8-2: Alignment A

Unknown to the design team at the time, there was a previous study prepared in 2002 that looked into a similar alignment. Key aspects of the previous study that happened to be further vetted during this study are as follows:

The previous bridge was assumed to have an 8-foot clear width which has been determined to be too narrow for current shared use pathways.

The south approach was assumed to be at-grade therefore requiring no ramp, but a ramp and/or elevator is required for both the south and north approaches.


The span length used for the previous study seemed to include the current MLK Jr. Way roadway, but did not seem to include the additional 50-foot future mass transit corridor. The span assumed in the previous report is likely 24% shorter than required.

ROW consideration was not included in the previous report. It was assumed that the square footage required for foundations and ramps was not significant. The ramp assumed in the previous report for the campus side is significantly less than required for current ADA access.

Other key considerations not included in the previous study that were include in the current study are as follows:

→ Current design code requirements

→ Inflation considerations from 2002

→ Input from local community stakeholders

→ Input from the general public

Alignment B This alignment connected to Sherman Street on the south side, then continued towards Grant Street along the sloped area between the railroad tracks and the private property boundary and crossed over to the campus node similar to Alignment A. This alignment was eliminated when it was found that the area of land designated for the pathway was owned by BNSF, who has plans for future track expansion within this area.

Figure 8-3: Alignment B


Alignment C The alignment is similar to Alignment A, but it connects to Sherman Street rather than Grant Street. The intersection of Sherman Street and Sprague Avenue is signalized and thus provides a safe crossing for pedestrians and bicycles. In addition, Sherman Street is a through street traveling south to the medical district and connecting with the overall non-motorized network of the City. There is also the opportunity to provide stairs that can connect with Grant Street.

This alignment also provides an opportunity to create a green space such as a park or plaza on the south side. Like Alignment A above, the bridge will be 26 feet above the ground surface when it crosses to the Riverpoint Campus. This again would require either a 370-foot ramp or an elevator for ADA access. Again, the disadvantage of this is the large area needed for the ramp which is not within the master plan of the campus and the long distance needed to be traveled for those unable to use a more direct stairway system.

Given the benefits of the connection to Sprague Avenue, the opportunity for a green space and the ability to utilize a shorter bridge, this alternative was chosen for further study. The height of the north approach required the use of an elevator on the north side (Riverpoint Campus). See Chapter 9, Approach Landing Study for further ramp versus elevator criteria and discussion.

Figure 8-4: Alignment C


Alignment D This alignment connected to Sherman Street on the south side and immediately crossed BNSF and landed at the intersection of MLK Jr. Way and the future north Sherman Street.

Like Alignment A, the bridge for Alignment D would be at a height of 26 feet above the ground once it crossed MLK Jr. Way. This would require a ramp for ADA access that is approximately 370 feet in length. The disadvantage of this length of ramp is the lack of space for the large area needed for the ramp and the long distance needed to be traveled for those unable to use a more direct stairway system.

Two sub-concepts were researched related to this alignment: D2 considered a ramp traveling north along the future Sherman Street extension on the east side of the future roadway. D3 considered the ramp traveling north along Sherman Street and east along the MLK Jr. Way corridor. Both sub-concepts were eliminated because they could not overcome the disadvantage of the large area needed for the ramps and the long distance needed to be traveled for those unable to use a more direct stairway system. In addition, these alignment alternatives would take pedestrians away from locations that would provide multiple travel directions for pedestrians. The alternatives also would create a visual and physical barrier to the Riverpoint Campus.

Figure 8-5: Alignment D


Alignment E This alignment connects with Sherman Street and then travels at an angle directly to the campus node defined by the intersection of pathways from the campus central spine or mall and Main Avenue. The advantage of this alignment is the intersection of Sherman Street and Sprague Avenue is signalized thus providing a safe crossing for pedestrians. In addition, Sherman Street is also a through street traveling south to the medical district and connecting with the overall non-motorized plan of the City.

Vertical clearance requirements above the City roadways and transit corridors are less than those required for BNSF; consequently, once the bridge crosses the BNSF right-of-way, the bridge height can begin to come down. Taking advantage of this opportunity, the bridge height could be reduced to approximately 16 feet, rather than the 26 feet required in other alignments. In turn, this reduces the ADA ramp length by approximately 140 feet for a total length of approximately 230 feet. The shorter ramp requires less land area to construct and can fit within the parameters of the campus master plan.

Figure 8-6: Alignment E


TRAIL ALIGNMENT RECOMMENDATION As noted in the Public Outreach section, refined Trail Alignments A and E were presented to the public during the first open house. The public was encouraged to vote for their preferred alignment. The results were Alignment E being favored by 75 percent of the participants. Alignment E was also chosen as the preferred alignment by the Mayor’s Advisory Committee as it allowed for a smaller ramp/landing footprint on the north side and a stronger connection to Sherman Street on the south side. It is also important to note that Alignment E does not require an elevator. See Figure 8-7 for Plan Layout.

In addition to the description of the refined Alignment E above, the following should be noted:

Aligning the south approach with Sherman Street will require creating a pathway between Sprague and Riverside Avenues.

Riverside Avenue is currently unimproved. We recommend improving Riverside Avenue to include full street pavement, drainage, lighting and landscaping at least immediately adjacent to the south landing improvements.

The south approach ramp is constantly sloped at 1:20 or 5 percent with generous curves 150 foot and 79 foot radii. A direct stairway aligned with the new pathway is also included.

The bridge is flat across the BNSF right-of-way as it must maintain 23.5 feet clear over the railroad tracks; however, in order to reduce landing height on the north landing, the bridge slopes at 5 percent from the arch pier to the north landing. Note the maximum constant longitudinal slope allowed by ADA accessibility guidelines is 5 percent.

In order to minimize the landing footprint, the north approach ramp is sloped more steeply at 1:12 with 5 foot landings every 30 horizontal feet per ADA accessibility guidelines. The ramp radius is 42 feet, but a direct stairway to the Riverpoint Campus central promenade is also included.

The total ADA path length from touch-down points of the ramp at Riverside Avenue to the ramp at the north landing is approximately 930 feet.

The total bridge length from the south to north abutment is 370 feet.


Figure 8-7: Preferred Alignment


9. Approach Landing Study APPROACH LANDING OPTIONS Development of the approach landing alternatives was driven by the height of the approach, length of the pathway and the available footprint for the landing.

APPROACH HEIGHT The height of the approach landing was set by the distance from the bridge walking surface to the at-grade ground surface. This distance set by the combination of the bridge depth, the required vertical clearance above the railroad, roadway and transit corridors and the maximum longitudinal slope of the bridge surface. Vertical heights from the bridge walking surface to the existing ground surface for the various alternatives varied from 30 to 15 feet.

RAMPS VERSUS ELEVATORS Landing options that included both elevator and ramp configurations were developed. It was decided during the development of the landings that any approach height above approximately 25 feet created a ramp length that was simply too long (350 to 500 feet). Consequently, any configuration requiring a height of this magnitude would use an elevator. Although the elevator options created the least footprint, the general public and the advisory committee all felt that elevators were the least desirable alternative. For the general public, concerns related to the elevator were about safety and access for bicycles and strollers. For the advisory committee, the concerns were regarding ownership of the elevator (e.g., whether it would be the university or the city), as well as the associated operation, maintenance activities, and costs. This single issue was instrumental in the overwhelming selection of Alignment No. 2 as the preferred alignment.


ELEVATOR ALTERNATIVES Landing options that included an elevator are described in the following renderings and details.

Figure 9-1: North Landing Scheme A


Figure 9-2: North Landing Scheme B


Figure 9-3: North Landing Scheme C

RAMP ALTERNATIVES

Slope Requirements The length of the pathway for the approach is established by the requirements of the Americans with Disabilities Act Accessibility Guidelines (ADAAG). The maximum vertical grade without landings is 1:20 or 5 percent. With landings, the grade is defined by a maximum of 30-inch rise for a 30-foot run. Landings are required to be a minimum of 5 feet in length.

For every vertical foot of grade change, the ramp length would need to be 20 feet for ramps without landings and approximately 14 feet for ramps with landings.

Figure 9-4: Accessible Ramped Pathway with Landings


Ramp Options The landing footprint is controlled by the layout of the pathway and the available real estate. Options included a ramp structure that turned upon itself, as shown in Figure 9-5, or raised earth fills with ramps traveling down the slope, as shown in Figures 9-3 and 9-6. The preference of both the stakeholders and the Mayor’s Advisory Committee gravitated towards the landform approach for the ramping design given its softer appearance than the highly structural systems of the earlier concepts.

Figure 9-5: North Landing Scheme D


Figure 9-6: North Landing Scheme E


INCORPORATING GREEN SPACE The inclusion of green space, especially on the south approach, was very important to those providing comments. The use of green space generated twice the comments of the next closest criteria. With this in mind, the team began looking into approach landings that minimized structural man-made elements and incorporated more natural components.

Figure 9-7: Green Space Development


Figure 9-8: Landing Options with Incorporated Green Space

Figure 9-9: Landing Options with Incorporated Green Space


10. Landscaping The north and south approach landings provide opportunities for landscaping enhancements. The north approach needs to blend into the multiple connections to the University, Main Avenue and the MLK Jr. Way corridor. The south approach can be an area that begins to define the future character of the South University District. In addition, the treatments must complement the structure itself as well as create a natural setting for the bridge.

While working with the Mayor’s Advisory Committee as well as collecting feedback from stakeholders and the general public, there was considerable interest in providing sustainable green space at both landings. Other considerations in the development of the landscaping were safety rails, sufficient lighting, seating areas, signage, drought resistant flora, traffic calming and opportunities for future artwork.

NORTH LANDING Characteristics of the landscaping for the north landing area are:

Clean modern concrete with form work details

— Beveled control joints

— Form tie dimples

— Cast-in-place or pre-cast caps

Terraced land form to break up the height of the concrete walls

Stamped patterns into concrete surfaces to differentiate the location

Decorative handrails

Contemporary lighting

Signage to direct users along Main Street, the Riverpoint Campus, etc.

SOUTH LANDING Characteristics of the landscaping for the south landing area are:

Concrete walls with brick veneer

Stone or concrete caps

Concrete walls with artistic reliefs or story information

Terraced land form to break up the height of the concrete walls

Stamped patterns into concrete surfaces to differentiate the location

Decorative handrails


Signage to direct users from Sprague Avenue to the bridge and places beyond contemporary lighting

Traffic calming considerations at the intersection of the pathway and Sprague Avenue

Figures 10-1 and 10-2 illustrate possible ramp treatments that fit within park improvements that can include edge enhancements, resting/picnicking areas, interpretive plaza spaces and overall landscape improvements.

Figure 10-1: North Landing

Figure 10-2: South Landing


11. Bridge Type Study GENERAL BRIDGE TYPES Key considerations in establishing the bridge type are length of span and depth of superstructure.

LENGTH OF SPAN With the alignment and bridge profile defined as described in Section 7, the next step in selecting the bridge type is to define the span length by determining possible foundation locations along the set alignment. For the University District bridge the foundations are required to remain outside the right-of-way for both the BNSF railroad and the new MLK Jr. Way. In addition, the bridge must remain outside a corridor north of MLK Jr. Way that is right-of-way for a future mass transit system. This meant that ends of the bridge could be founded at the southern edge of the BNSF right-of-way and the northern edge of the future mass transit corridor. A single intermediate foundation could be located between the BNSF and MLK Jr. Way right-of-ways. This creates the ability to construct a two span bridge with spans of approximately 170 feet and 200 feet for a total bridge length of approximately 370 feet.

Structural types that are commonly used for conventional site conditions with spans in the 200-foot range like the University District Pedestrian Bicycle Bridge include steel and concrete box girders, steel plate girders, and steel trusses. For sites with special conditions and aesthetic considerations, structural types also include cable-stayed, suspension, and arch bridges.

DEPTH OF SUPERSTRUCTURE The bridge allowable superstructure depth is set by the distance between the bridge profile for the walking surface and the required vertical clearance below the bridge. The bridge profile was discussed in Section 7. Key vertical clearances below the bridge are the following:

MLK Jr. Way: 17 feet 6 inches

BNSF: 23 feet 4 inches

Mass Transit: 21 feet 6 inches

The allowable superstructure depth between the bridge profile for the walking surface and the required vertical clearances is approximately 36 inches. This depth would eliminate the typical box girder and plate girder bridge types, because they would require depths in the range of 8 to 10 feet. Consequently, truss, arch and cable-stay bridges are the remaining possible bridge alternatives.


STEEL TRUSSES The steel truss system is one of the oldest types of bridge styles. Commonly the truss is very rectilinear utilizing forms such as triangles, squares, and rectangles. This bridge creates a more enclosed experience, as the structure surrounds the user on all sides. The truss bridge will have a more subdued appearance against the city skyline as the structure is fairly compact.

Two truss styles were developed for the project. One truss had the side members canted to the center of the bridge forming a triangle. The other had the side members canted to the outside forming a trapezoid. The two forms provided a choice between a more enclosed environment with the triangle versus a more open environment with the trapezoid.

Truss Pros and Cons Pros

Less susceptible to wind and human generated vibrations

Easier construction with the ability to launch the truss over the BNSF tracks

Truss is a stable structure even before the construction is complete

Cons

Unable to easily accommodate a horizontal deck radius for a curved alignment

Requires a large depth to accommodate deflections

Likely to block views more than the other bridge styles under consideration

Less iconic and more utilitarian


Figure 11-1: Triangle Truss


Figure 11-2: Canted Truss


ARCH STYLE There are basically two styles of arches. Their difference lies in the way the forces from the arch are transmitted into the foundation. In both styles of arches the vertical loads such as the self weight of the structure and pedestrians on the deck are carried through vertical suspension members to the arch. This loading condition pulls the arch downward while pushing the ends outward. For a compression arch structure this load is transmitted through the arches directly into the abutments. A tied-arch transmits outward horizontal forces at the base of the arch into a bottom tension chord. The bottom chord can either be tension ties or the deck itself. The elimination of horizontal forces at the abutments allows tied-arch bridges to be constructed with less substantial foundations; consequently, they can be situated upon elevated piers.

The arch system developed for this project was an inclined arch with only a single supporting arch rotated from its typical vertical position. Another distinguishing feature of the inclined arch system is the option between a straight pathway and curved pathway across the bridge. For the curved pathway the deck and supporting arch curve in opposite directions allowing each to balance and react with one another. This helps significantly in the resistance of out-of-plane loads. By using struts that can resist tension and compression, rather than cables that are simply tension members, the structure is much stiffer.

The arch bridge style can have a grander appearance than the truss style with a distinct presence against the skyline. Both arch styles, however, have a relatively low profile similar to the truss.

Arch Pros and Cons Pros

Less susceptible to wind generated vibrations with strut versus the typical cable supports

Structure located only on one side of the bridge for a more dramatic, open look

Cons

Tie must be constructed before the arch can function

Arch must be braced until the deck is installed making construction over the roadway and railway more difficult

Large torsion tube required to restrain transverse rotation due to pedestrian live loading


Figure 11-3: Straight Arch


Figure 11-4: Curved Arch


CABLE-STAY STYLE A cable-stayed bridge supports the bridge deck with cables that are supported from a tower or pylon. There are two major styles of cable-stayed bridges. The harp design has cables nearly parallel to each other with attachments at various points along the height of the pylon. The cable distance vertically along the pylon is proportional to the distance along the edge of the deck structure. The fan design has the cables attached along the length of the deck structure; however, unlike the harp alternative, all of the cables are supported at a single point at the top of the pylon.

In the cable-stayed bridge, the pylons form the primary load-bearing structure. The deck will cantilever as it builds away from the pylons. Once the cantilever no longer can support itself, cables are added to support the deck back to the pylon.

With simple cable supports along the sides of the bridge, the cable-stayed is the most open of the bridge alternatives. This will allow users an unobstructed view from the bridge deck. Another feature unique to the cable-stayed alternative is the center pylon. The tower is approximately 120 feet above the existing ground line and 90 feet above the bridge deck surface. This allows the bridge to be seen from a distance and creates a visual landmark.

Cable-Stay Pros and Cons Pros

Superstructure can be designed to support its self weight allowing it to be constructed in a single piece over the roadway and railway similar to a truss

Cable support allows for an unobstructed view off of the bridge

Tower or pylon height creates a visual landmark locating the bridge from a distance

Cons

More susceptible to wind and human generated vibrations

Slightly more costly than other alternatives


Figure 11-5: Cable Stay Point


Figure 11-6: Cable Stay Bow


BRIDGE TYPE SELECTION PROCESS AND RECOMMENDATION An overview of possible bridge styles was presented to the Mayor’s Advisory Committee during project workshops. A wide range of bridge styles were depicted through pictures, sketches and simple physical models. Several straight and curved bridge styles were presented to facilitate discussion meant to establish a variety of viable alternatives.

In addition to the Mayor’s Advisory Committee workshops, meetings were held with representatives from the City’s bridge engineering and bridge maintenance departments. During these meetings, topics such as inspections and maintenance were discussed. These two topics are particularly important due to the need to perform both inspection and maintenance above the BNSF right-of-way. Any need to bring equipment on to the BNSF right-of-way for inspection and maintenance would require an easement from BNSF. Every effort is going to be made to incorporate the inspection and maintenance needs within the structure itself.

From the many bridge alternatives discussed with the Advisory Committee, several options were selected to present to the general public and stakeholders for their input. Initial outreach to the public occurred through the project blog and during the project’s first open house. Graphics created for public review and comment included renderings of bridge alternatives representative of truss, arch, and cable-stayed styles.

Results from the public surveys and open house comments eliminated the truss as an alternative, but did not provide a clear preference between the arch and cable-stayed styles. A second outreach occurred in order to determine the public’s inclination to either the arch or cable-stayed styles. The project blog was updated and a second open house occurred. Graphics created for public comment included a 3-D flythrough of both the arch and cable-stayed alternatives.

The cable-stayed bridge style was a two-to-one favorite coming out of the second public outreach process. The outreach results we first presented to the Mayor’s Advisory Committee, then to the Mayor and the Mayor’s Cabinet, who agreed to bring the cable-stayed style to the Spokane City Council for approval as the preferred alternative. In June of 2011, the City adopted a resolution specifying the cable-stayed bridge as the alternative to move forward through the type, size and location study.


Figure 11-7: 3D Straight Cable Stayed Bow, Looking West

Figure 11-8: 3D Straight Cable Stayed Bow, Looking Southeast


Figure 11-9: 3D Straight Cable Stayed Bow, Looking Northwest


12. Electrical/Lighting CODES AND STANDARDS The electrical systems will be designed to conform, as a minimum, to the following codes and standards:

International Electrical Code (IEC)

International Building Code (IBC)

International Fire Code (IFC)

National Electrical Code (NEC)

Regulations of the State Fire Marshal

Electrical Safety Orders of the Washington State Department of Labor and Industries (DL&I)

Washington Administrative Code (WAC)

Requirements of Washington State Industrial Safety and Health Administration (WISHA)

Requirements of Washington State Department of Transportation (WSDOT)

Americans with Disabilities Act (ADA)

Illuminating Engineers Society of North America (IESNA)

Standards of the National Fire Protection Association (NFPA)

Underwriters Laboratories (UL)

Applicable state and local ordinances

SERVICEABILITY All panelboards, lighting control contactors, disconnect switches, junction boxes, and other electrical equipment requiring service shall be located in accessible areas as described in the NEC.

Luminaires shall be located with consideration giving to future maintenance and repair. Luminaire technology has been selected to minimize the interval of required maintenance including lamp replacement.


ENERGY CONSERVATION The illumination technology proposed has been specifically selected based upon several criteria including efficiency and shall meet or exceed all of the requirements of the applicable codes. Luminaries utilizing lamp types with particularly high efficacy have been proposed to promote energy conservation.

At a minimum, electrical energy conservation features should include:

An automatic lighting control system shall be used to control not only the bridge deck luminaires and pathway lighting at the approaches on either end, but also the decorative lighting accenting the bridge architecture.

Use of exterior area and roadway lighting using LED sources will be considered as another means of energy savings.

SITE UTILITIES Avista Utilities is the electrical utility service provider for this site. Construction of the nearly complete MLK Jr. Way – Phase 1 project (just north of the BNSF Railroad right-of-way) has necessitated Avista Utilities demolition of the existing aerial power lines supplying BNSF signal systems and facilities on the north side of the tracks. This infrastructure was demolished in fall 2011. After completion of this work, two available sources for electrical power in the vicinity of the proposed bridge location will remain (see Avista Utilities GIS Map in Appendix E).

First, there are existing aerial lines providing 120/240V, 1-phase power to the buildings located between Sprague Avenue and the BNSF right-of-way. These power lines are supported on existing poles along the south side of Riverside Avenue starting at Grant Street and extending east. Demolition of a number of small structures on the north side of Riverside Avenue to accommodate the proposed bridge will provide ready access to this power source. There are three options for accessing this infrastructure.

Option 1a – Aerial This option would require an overhead service drop from the power lines and transformer bank located at or slightly west of Riverside Avenue and Sheridan Street to a service mast located at the service enclosure on the project site. This is the least-cost scenario, requiring only the minimum Avista Utilities service connection charges.

Option 1b – Aerial and Underground This option would require an overhead service line extension north across Riverside Avenue near the intersection of Riverside Avenue and Sheridan Street to a new wooden power pole. At this location, a conduit riser could be installed down the pole and route underground to the service enclosure and metering equipment. This scenario requires not only the minimum Avista Utilities service connection charge but also the cost of the additional pole and aerial conductors.

Option 1c – Underground This option would require an underground service conduit provided by the customer across Riverside Avenue to the pole near the intersection of Riverside Avenue and Sheridan Street. Again, a conduit riser would be required at the pole to accommodate Avista Utilities connections. This scenario


requires not only the minimum Avista Utilities service connection charge but also the customer would be responsible for the service entrance conductors between the top of the conduit riser and the service equipment enclosure and metering equipment.

Second, Avista Utilities indicated that due to the construction of MLK Jr. Way and demolition described above, the nearest source of power north of the BNSF right-of-way is 3-phase power available some distance to the north, near Spokane Falls Boulevard. Considering that the electrical loads consist only of single phase lighting, the additional costs to provide 3-phase power were deemed to be unjustified and this alternative was dismissed.

Finally, there are existing aerial communications and signal cables supported by wooden poles along the south edge of the BNSF right-of-way. These cables appear to interfere with the proposed bridge. However, it is understood that these cables are no longer in service and will be demolished.

ELECTRICAL POWER DISTRIBUTION SYSTEM It is anticipated that regardless of the selected source for electrical power to the project, Avista Utilities will supply power to the customer furnished service entrance, the metering equipment, and make final connections at the point of service. This is typically at the mast or weather head.

Service equipment will consist of a service entrance rated dead-front commercial panel board with main circuit breaker and integral surge protection. The metering equipment will consist of a customer furnished meter base and meter furnished by Avista Utilities. The service and metering equipment indicated above will be housed inside a metal enclosure supported by a pre-cast concrete base. This enclosure will be provided with a convenience outlet and task light to facilitate maintenance and trouble shooting.

Individual branch circuits will extend from the over-current protection devices, anticipated to be 2P-20A molded-case circuit breakers, through the lighting control panel contactors/relays, then continue to the luminaires supplied.

All service entrance, feeder and branch circuit conductors shall be electrical grade copper with insulation listed for installation in wet locations. All branch circuits will be provided with a dedicated neutral conductor. Shared neutral conductors are not recommended.

LIGHTING AND CONTROLS Lighting will be selected to complement and accent the bridge architecture while providing adequate illumination for security and safety on the bridge deck as well as the pedestrian pathways (see Lighting Fixture Cut Sheets in Appendix E). Special consideration will be given to the selection and placement of each individual luminaire to ensure the general and accent illumination conforms to BNSF light trespass criteria.

In general, illumination will be provided to the following levels:

Bridge Deck and Pedestrian/Bicycle Pathways shall be designed with a minimum average of 1.0 horizontal foot-candles and an average to minimum ratio of 4:1. Vertical foot-candles shall be a minimum average of 0.5 at 60 inches AFF.


Luminaires have been selected to utilize LED or high intensity discharge lamp sources such as LED and metal-halide. Color-changing LED Accent lighting is located at the top and near the bottom of the inside of each side of the cable support bow. These LED sources are capable of pre-programmed or automatic changes in color and intensity. Illumination of the bridge deck and pathway are provided by LED bollards. Illumination of the support cables is provided by pole mounted metal-halide flood lights. These poles are mounted to the bridge deck and the flood lights are aimed to accentuate the structure.

An automatic lighting control system including a photoelectric sensor shall be used to control all luminaires. It is recommended that the lighting controls consist of a programmable low voltage lighting control system capable of interfacing directly with color changing LED drivers to implement pre-programmed color changing patterns as well to adjust illumination of accent lighting to the ambient conditions.


13. Right-of-Way Requirements WSU RIVERPOINT CAMPUS The north end of the proposed bridge lands on the WSU Riverpoint Campus displacing existing parking lot improvements and associated infiltration planters. The WSU property required for the bridge landing is approximately 1 acre. Approximately 42 parking stalls will be displaced by the footprint of the landing, however, an additional 16 stalls will be lost in order to reconfigure the drive aisles cut off by the landing.

TRANSIT CORRIDOR The future transit corridor is adjacent to the north side of MLK Jr. Way and is 50 feet wide to accommodate future rail and/or bus transit. The corridor currently occupies a linear parking lot on the south edge of the WSU Campus. We have assumed the limits of this corridor based on the East Riverside Extension Spokane Regional Light Rail – Alignment Option 8, dated August 21, 2009.

The proposed pedestrian bridge spans over the transit corridor with the landing just north of the right-of-way. Typically, the minimum vertical clearance above pavement for light rail is 15 feet with a preferred clearance of 18 feet to 20 feet for the catenary system. The minimum clearance provided as measured from the existing grades to the underside of the proposed bridge is 21.5 feet. These vertical dimensions will need to be verified as design progresses so that the minimum clearances are maintained.

It is likely the transit corridor would support a station adjacent to the north landing. Future design advancements could integrate the landing design with the station design if timing of projects coincides.

MLK JR. WAY The proposed bridge spans MLK Jr. Way between the center arch pier and the north landing. The minimum provided vertical clearance from the underside of the bridge is approximately 25 feet, which is well clear of the 17.5 feet required vertical clearance for a pedestrian bridge over a road per the WSDOT Design Guide.

The center arch pier lands within the MLK Jr. Way right-of-way between the south curb and the property line with BNSF Railway. The pier footing fits within this area with little room to spare. Therefore, as design progresses, the footing location will need to be verified that it is confined between the curb and the BNSF property line. Also, the minimum clearance of 3.5 feet between the face of curb and face of pier will need to be maintained.

The project will need to utilize drainage and sprinkler system infrastructure in MLK Jr. Way to support the bridge.


BNSF The proposed bridge spans over the BNSF Railway right-of-way between the south landing and the center arch pier. Three sets of railroad track lines are crossed within the right-of-way. The vertical clearance between the underside of the bridge and the top of the rails is 23.5 feet, which is the minimum distance required by BNSF. This elevation is held constant across the entire BNSF right-of-way.

SOUTHSIDE PARCELS

South Landing The south end of the bridge lands on several property parcels comprising 2.15 acres requiring the purchase of 16 parcels from four land owners. The landing includes area necessary for storm drainage facilities but can also double as park amenity. The proposed improvements will displace three building structures.

Riverside Avenue Riverside Avenue is currently an unimproved 60 foot wide right-of-way serving as vehicular and utility access to the adjacent parcels. While the south bridge landing is fully contained within the proposed parcels, improvements to Riverside Avenue would be desirous as part of the bridge project. These improvements at a minimum would include paving the street. Other improvements could include curb, sidewalk, lighting, and landscaping.

Sherman Street The proposed bridge south landing lines up along the axis of Sherman Street, which currently terminates at Sprague Avenue. This project proposes to create a pathway from Sprague Avenue to the bridge (crossing Riverside Avenue) in order to provide a direct connection along the Sherman Street axis. This proposed pathway will require the purchase of five parcels from two property owners.

Though not part of the current project, the proposed configuration of Sherman Street can be similar to the current Sherman Street layout and typology of that south of Sprague Avenue or it can be entirely different. The current proposed extension is simply an asphalt pedestrian path. In the future the pathway could be a road with generous pedestrian walks containing planting and lighting that invite the traveler toward the bridge. The extension could also contain angled parking if this served future business and program functions.

Grant Street The proposed bridge project does not include improvements to Grant Street, however, future improvements will be necessary as the surrounding properties are redeveloped and the City desires to activate and stimulate the area.

Sheridan Street Similar to Grant Street, the bridge project does not include improvements to Sheridan Street but for the overall activation of the block and integration with the bridge, future improvements to this street will be necessary.


Figure 12-1: Parcel Map


14. Storm Drainage EXISTING CONDITIONS

North Landing The area encompassing the proposed north landing is approximately 32,500 square feet, which is approximately equally divided between impervious and pervious surfaces composed of grass infiltration swales that serve the existing parking lot.

In general, the soils are composed of fill material over shallow bedrock approximately 1-2 feet below the surface grades. Currently, all storm water runoff infiltrates within the grass swales.

Bridge The area under the proposed bridge contains all impervious surfaces except for the new drainage swales constructed in conjunction with the new MLK Jr. Way. Furthermore, except for the new MLK Jr. Way, there are no drainage facilities. Stormwater runoff within the BNRR right-of-way ponds in low spots and eventually infiltrates.

South Landing The area encompassing the proposed south landing is approximately 37,500 square feet and is entirely composed of impervious surfaces. There are no existing drainage facilities within this area; the storm water runoff ponds on the surface, and eventually infiltrates.

The area is overlain with silty fill with variable bedrock depths. Bedrock is generally deeper near the top of the slope (approximately 18 feet in one boring) and more shallow adjacent to Riverside Avenue (7 feet in one boring and 2.5 feet in another).

Sherman Street and Riverside Avenue The area within the proposed Sherman Street extension between Sprague and Riverside Avenues is entirely impervious with no existing drainage facilities. There is a 7-foot grade drop from Sprague Avenue to Riverside Avenue. Riverside Avenue is an unimproved street with no drainage facilities as well.

We suspect the soils in these areas have shallow bedrock overlain by silty fill.

There is a combined sewer in Sprague Avenue that could be utilized west of Grant Street.

PROPOSED STORM WATER FACILITIES

North Landing The proposed landing surfaces approximately match the pervious/impervious ratio of the existing surfaces so this area should not experience increased storm water concentrations. The area, however, contains existing grass planters that will be displaced by the landing. These planters serve the existing parking lots and will need to be replaced.


The proposed landing can be designed such that all the storm water can be infiltrated on site. Any excess runoff can be collected and piped to the new drainage swales serving MLK Jr. Way. Stormwater collection/infiltration will be dispersed as much as possible to reduce individual infiltration facility size. Paved areas could utilize porous pavements and planter areas can serve as infiltration basins. Drywells are not an option for this area due to the shallow bedrock.

Water quality is not required because the landings will not be pollutant generating surfaces.

Bridge Stormwater runoff on the proposed bridge deck will be sloped to one side and channeled to area drains and conveyed via piping to downspouts located on the center arch pier and the pier at the north landing. Alternatively, runnels (drainage channels) could convey storm water to the same points of discharge.

The downspouts will convey the bridge runoff to the new storm drainage system in MLK Jr. Way.

South Landing Since storm water infrastructure does not exist within this area and City policy does not allow use of the combined sewer for new storm drainage discharges, infiltration facilities will be utilized. Similar to the north landing, storm water collection and infiltration will be dispersed rather than concentrated to reduce the size of any particular infiltration facility. Porous pavements should be considered as well as planted infiltration swales/basins.

Note that the proposed improvements will have converted more than half the area to pervious surfaces, which will improve the hydrologic conditions.

Water quality is not required given that the new improvements do not contain any pollutant generating surfaces.

Drywells can potentially be utilized where the existing fill is deeper than 12-feet; however, they probably will not be necessary.

Sherman Street and Riverside Avenue The proposed trail, utilizing a Sherman Street alignment, as well as the improvements to Riverside Avenue will be more challenging for infiltrating storm water given that the new surfaces will be mostly impervious and include pollutant generating surfaces. Drainage strategies for these areas include utilizing the park space west of the bridge landing for bio-filtration for water quality. Infiltration would be achieved by utilizing shallow infiltration swales or new tree wells adjacent to streets. Depending on the infiltration rates, storage may be required to handle peak storm events. A buried pipe with perforations could work in lieu of a surface basin.


15. Utilities SANITARY SEWER Restrooms are not proposed; therefore, sanitary sewer infrastructure is not required. Existing sewer infrastructure will not be affected by the proposed improvements.

POTABLE WATER Potable water is required for irrigation for the landing improvements. Irrigation was placed adjacent to MLK Jr. Way and should be available for the north landing. There is an existing water main in Riverside Avenue that can be used for the south landing.

OVERHEAD UTILITIES Existing overhead power and communication utilities that span the bridge alignment will need to be relocated. The overhead lines south of the BNSF right-of-way can possibly be rerouted to the south side of Riverside Avenue, then back to the edge of the BNSF right-of-way at Sheridan Street. However, the overhead lines north of the BNSF right-of-way will need to be relocated underground, which will require the elimination of one utility pole.

UTILITIES ON THE BRIDGE In addition to creating pedestrian and bicycle access over the BNSF railroad, MLK Jr. Way, and the future Mass Transit corridor, the bridge will also establish an effective crossing point for utilities. Avista, the regional electricity provider, has already requested access to the bridge for conduit crossings. Avista and other utilities will be contacted during final design to coordinate access.


16. Cost Estimate Preliminary cost estimates were developed for three alignment alternatives. The cost estimates included the bridge construction costs, approach costs and anticipated right-of-way cost. These costs were used simply to get an order-of-magnitude comparison between each alignment. Through the selection process, Alignment No. E became the preferred alternative for reasons stated in Section 7.

For the bridge type, alternatives were narrowed to the inclined arch and the cable-stayed bridge styles per Section 10. The preliminary cost estimates were then updated to reflect the refined alternatives which then identified the cost of the inclined arch alternative as being 6 percent higher than that of the cable-stayed alternative. This information was provided as part of an updated survey and second open house presentation to distinguish if this cost difference was important for the selection process. Approximately 70 percent of the respondents stated that the 6 percent variation would not be a factor in their decision making process.

The resulting preferred selection was the cable-stayed bridge along Alignment E. The design was then further refined and a more detailed cost estimate created. Figure 16-1 identifies the extent of each of five sections of the project as they correspond to the cost summary (Figure 16-2). A detailed cost estimate is included in the figures that follow.

COST RANGES The estimated cost range of the bridge per the findings of the TSL study is between $14 and $16 million. The project costs will be effected by a number of variables. A few key variables include timing for project construction, final geometry of the structure and actual ROW acquisition costs.

Inflation It is assumed that inflation will be a factor in the final cost of the project. Assuming 5% inflation per year, the project will see approximately a $500,000 increase for each year that passes before construction begins.

Final Geometry Throughout the study process, the pathway width has been an item of interest for a variety of stakeholders. Currently, the cost estimate is based upon a clear pathway width of 14 feet. For each additional foot of width increase, it should be assumed that the total project cost will increase by approximately $520,000. This increased cost is approximate for each foot of increase up to a total clear width of 16 feet.

ROW Aquistion Negotiations related to property acquisition have not taken place; therefore, the ROW values included in the cost estimate are simply placeholders utilizing the best available information at the time of the study.


COST ESTIMATE

Figure 16-1: General Cost Breakdown Limits


Figure 16-2: University Pedestrian Bridge Construction Fee Estimate













Figure 16-8: University Pedestrian Bridge Construction Fee Estimate (Continued)







17. Summary and Recommendations The pedestrian bicycle bridge type, size and location process developed multiple alignments, landings and bridge alternatives. The type, size, and location (TSL) study had the following key components and activities:

Site Data Collection Activities

— Topographic and boundary survey

— Geotechnical exploration

Permitting Activities

— Phase I Environmental Site Assessment (ESA)

— State Environmental Protection Process (SEPA)

— WSDOT Environmental Classification Summary (ECS)

— Cultural Resources Evaluation

Planning Activities

— Urban/Contextual planning

Outreach Activities

— Mayor’s Advisory Committee

— Public Involvement

o Open Houses

o Project Blog

o Project Surveys

Engineering Activities

— Geotechnical Engineering

o Foundation recommendation

o Filtration

— Civil engineering

o Alignment plan and profile

o Utilities

o Surface water


— Structural Engineering

o Bridge superstructure type and size

o Bridge foundation type and size

— Architectural activities

o Bridge aesthetics

o Landscaping

— Mechanical/Electrical Engineering

The objective of the TSL study was to define the preferred alternative for the trail alignment, approach landing character and the bridge type and size. The selection of the preferred alternative was accomplished using input from both the Mayor's Advisory Committee and a public outreach program.

TRAIL ALIGNMENT The preferred alignment ties Sherman Street with the intersection of the spine of the Riverpoint Campus and Main Avenue. The alignment’s southern approach starts at the intersection of Sprague Avenue and Sherman Street then travels north on a multi-use pathway to the future transit corridor. The pedestrian bicycle bridge then travels over the BNSF, MLK Jr. Way, and transit corridors then touches down at an intersection with the spine of the Riverpoint Campus and Main Avenue.

Key attributes of the preferred alignment are:

Aligning the south approach with Sherman Street will require creating a path along the Sherman Street alignment between Sprague and Riverside Avenues.

Riverside Avenue is currently unimproved. It is recommended to improve Riverside Avenue to include full street pavement, drainage, lighting and landscaping immediately adjacent to the south landing improvements. Additional improvements to Riverside Avenue are not included in this project.

The south approach ramp is constantly sloped at 1:20 or 5 percent with generous curves 150 foot and 79 foot radii. A direct stairway aligned with Sherman Street is also included.

The bridge is flat across the BNSF right-of-way as it must maintain 23.5 feet clear over the railroad tracks; however, in order to reduce landing height on the north landing, the bridge slopes at 5 percent from the arch pier to the north landing. Note the maximum constant longitudinal slope allowed by Americans with Disabilities Act (ADA) accessibility guidelines is 5 percent.

In order to minimize the landing footprint, the north approach ramp is sloped more steeply at 1:12 with 5 foot landings every 30 horizontal feet per ADA accessibility guidelines. The ramp radius is 42 feet and a direct stairway to the Riverpoint Campus central promenade.

The total ADA path length from touch-down points of the ramp at Riverside Avenue to the ramp at the north landing is approximately 930 feet.

The total bridge length from the south to north abutment is 370 feet.


APPROACH LANDINGS Landing options that included both elevator and ramp configurations were developed. It was decided during the development of the landings that any approach height above approximately 25 feet created a ramp length (350 to 500 feet) that was simply too long. Consequently, any configuration requiring a height of this magnitude would use an elevator. Although the elevator options created the least footprint, the general public and the advisory committee all felt that elevators were the least desirable alternative. For the general public, concerns related to the elevator were about safety and access for bicycles and strollers. For the advisory committee, the concerns were regarding ownership of the elevator whether it would be the university or the city and the associated operation and maintenance activities and costs. This single issue was instrumental in the overwhelming selection of approaches that utilized ramps rather than elevators.

Both structural and landform type ramps were studied. The preference was towards the more landform approach for the ramping design yielding a softer appearance than the highly structural concrete or steel ramping systems.

BRIDGE TYPE AND SIZE For the University District bridge the foundations are required to remain outside the right-of-way for both the BNSF railroad and the new MLK Jr. Way. In addition, the bridge must remain outside a corridor north of MLK Jr. Way that is right-of-way for a future mass transit system. This meant that ends of the bridge could be founded at the southern edge of the BNSF right-of-way and the northern edge of the future mass transit corridor. A single intermediate foundation could be located between the BNSF and MLK Jr. Way rights-of-way. This creates the ability to construct a two span bridge with spans of approximately 170 feet and 200 feet for a total bridge length of approximately 370 feet.

The key factor in the development of bridge alternatives was the desire to keep the superstructure depth as shallow as possible. This was due to the impact that the structural depth had to the overall ramp lengths and the required clearances over the BNSF/MLK Jr. Way/Transit corridors. A wide range of bridge styles were studied that were capable of spanning 200 feet while minimizing the superstructure depth including, truss, arch and cable-stayed bridges. Several straight and curved bridge styles were also studied. From the many bridge alternatives, there was a clear preference between the arch and cable-stayed styles. The cable-stayed bridge style was a two-to-one favorite coming out of the public outreach process. In June of 2011, the City adopted a resolution specifying the cable-stayed bridge as the alternative to move forward through the type, size and location study.

COST ESTIMATE The preferred combination of alignment, landings and bridge type was advanced to a level that provided enough design to establish a preliminary project cost estimate. The estimate includes the costs for completing the bridge and landing design, purchasing needed right-of-way and construction of the project.

The estimated cost range of the bridge per the findings of the TSL study is between $14 and $16 million. The project costs will be effected by a number of variables. A few key variables include timing for project construction, final geometry of the structure and actual ROW acquisitions costs.




NEXT STEPS Following the review and discussion of this study, as the project continues into the final design phase, it is recommended that the next steps include:

Perform final design of plan and profile for selected trail alignment.

Perform final structural design of preferred bridge structure and approaches.

Though the intermediate pier is located out of the BNSF ROW, given the nonredundant nature of the single intermediate pier, assess the consequences from a derailed train.

Investigate the pressure changes of high speed trains.

Investigate sight lines to railroad signals.

Develop construct phasing methodologies related to construction over BNSF, MLK Jr. Way and the Spokane Transit Authority corridor.

Explore property acquisition.

Complete any remaining environmental components.

Update environmental studies as needed and determine costs for permitting and mitigations.

Continue coordination with Mayor’s Advisory Committee, stakeholders, and the public.

Finalize required vertical clearance above the Spokane Transit Authority’s corridor. Coordinate with both STA and WSU to confirm future intentions for mass transit in this area.

Coordinate options for locating facilities on the bridge with local utilities

Date post:	10-Aug-2020
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