THE PENNSYLVANIA STATE UNIVERSITY Department of Civil and Environmental Engineering CE 421W: Transportation Design FINAL REPORT DELIVERABLE INTRODUCTION The objectives of the final report are to: Describe the process used to arrive at the final recommended alternative alignment for the US Route 322 study corridor. This discussion should include the existing conditions analysis, proposed alternative design concepts, and the final design recommendation. Present the final recommended design in a set of roadway construction drawings. Project Introduction Transportation deficiencies exist in south central Center County, Pennsylvania. Exacerbating the problem is the growth that is expected to occur in the region over the next 25 years. Not only is additional capacity a primary consideration, so too are safety improvements and non-traditional transportation alternatives. Transportation improvements along U. S. Route 322, PA Route 144, and PA Route 45 are desired. See Figure 1 for study area and its boundaries. FIGURE 1. Study Area U. S. Route 322 currently provides inadequate flow with its volume of traffic. Areas of the existing roadway provide fair design consistency for passenger cars while poor design
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THE PENNSYLVANIA STATE UNIVERSITYDepartment of Civil and Environmental EngineeringCE 421W: Transportation Design
FINAL REPORT DELIVERABLE
INTRODUCTION
The objectives of the final report are to: Describe the process used to arrive at the final recommended alternative alignment for the US
Route 322 study corridor. This discussion should include the existing conditions analysis,proposed alternative design concepts, and the final design recommendation.
Present the final recommended design in a set of roadway construction drawings.
Project Introduction
Transportation deficiencies exist in south central Center County, Pennsylvania.Exacerbating the problem is the growth that is expected to occur in the region over the next 25years. Not only is additional capacity a primary consideration, so too are safety improvementsand non-traditional transportation alternatives. Transportation improvements along U. S. Route322, PA Route 144, and PA Route 45 are desired. See Figure 1 for study area and its boundaries.
FIGURE 1. Study Area
U. S. Route 322 currently provides inadequate flow with its volume of traffic. Areas ofthe existing roadway provide fair design consistency for passenger cars while poor design
consistency for truck in the same stretch of roadway. The poor design consistency restricts thespeed of trucks which inadvertently slows the flow of traffic and creates queuing. This is clutchwhen some areas see an upwards of 20% trucks. Not only does this create queuing but as raiseconcerns on rear end accidents. Speed perception is lacking in inexperience, older and distracteddrivers. One may approach the queuing line more rapidly than expected and not have enoughtime to decelerate. Other safety concerns are as follow:
1. Horizontal curve radius2. Lane width3. Traffic volume
Traffic volumes have increased steadily in the study area over the last 10 years. The USRoute 322 study corridor has experienced an annual traffic growth rate of approximately 2.2percent. This growth is placing stress on the existing roadway network, and will continue to doso for the foreseeable future.
Road conditions need improvement due the annual traffic growth rate (2.2%). Theseimprovements will need to handle larger volumes of passenger cars and truck traffic as thesurround areas develop. Adequate route of transportation is needed to support the populationincrease. As the population increases, so does the need of good and supplies. Trucks are thelogical form of transportation to support these communities. Therefore increasing communitiesare directly related to larger truck traffic.
The engineering group will try to solve the current problems by coming up with a new designproposal. The specific needs for this project are the following:
1. Satisfy the increasing demand for traffic capacity2. Improve the traffic safety3. Improve the traffic consistency4. Decrease the environmental impact while working on the construction project
Existing Design and Traffic Characteristics
The current horizontal and vertical alignments pose an issue for the current roadway.Multiple segments along the vertical alignment need reconstructed. As 28 of the existing curveseither sag or crest are less than the minimum horizontal distance (K) for a curve or Kmin.Numerous existing curves have inadequate lengths due to its reduced K. The length required toprovide adequate horizontal distance is directly related to K per the equation L=KA. Re-evaluating this alignment is in consideration. See Appendix B for existing K-values
Table 1 shows traffic volume (both directions) and truck percentage data based on 2009traffic counts. It also shows the project traffic for 2034 at a growth rate of 2.2%
TABLE 1. Study Area Traffic Volumes and Growth Rates.
Location 2009AADT
2034AADT
2009 TruckPercentage
US 322Between Jacks Mill Road and Elks Club Road
13,200 19,960 17%
US 322Between Sharer Road and Wagner Road
12,000 18,145 19%
US 322Between Dogtown Road and Mountain Back/Red MillRoad
11,200 16,935 20%
Note: Annual Growth Rate in AADT is 2.2% per year
This data was collected in 2008 during a typical weekday, and are provided in Appendix A. TheAM and PM peak periods are noted as are the truck percentages at the following intersections:
US Route 322 and Wagner Road US Route 322 and Taylor Hill Road US Route 322 and Neff Road US Route 322 and Mountainback/Red Mill Road US Route 322 and PA State Route 144
Safety Evaluation of Existing Conditions
For Safety Evaluation, the analysis is based on Horizontal Alignment Data for US Route322. The original Safety Evaluation reveals severe problems in a couple of road sections inRoute 322. The most obvious findings are the high accessing rate in the original design. From thecalculation of the engineering group, the access points/mile is 15, which already exceed theAASHTO requirements. Another significant finding is the complex road situations. Most of theroad is in rumble strips. Also, driveway density and superelevation rate surveyed from past fewyears revealed a comparatively higher roadway traffic demand than the design values. The thirdfinding is the accident rate in the entire Route 322. From the surveyed value from year 2005 to2009, the annual crashes are 32. Furthermore, over 70% of the crashes cause injuries or fatalities.
Most of the essential information is taken from Appendix C on the project spreadsheet,Based on the equation and Crash Modification factors calculation, radius, curve degrees, PC, PIand PT stations are used for the safety evaluation. Also, the stations data can be applied forsegments division.
The Crash Data in the attachment is also important. From that, the AADT and crashesdata are obtained in certain segments. All these are essential values for Safety Evaluation check.
Then, based on the equations on AASHTO Green Book, suitable equations are used on differentCrash Modification factors. Compared the actual crash data with prediction data, the final resultsare obtained and attached in the Appendix. From the table, only segments 30, 32 and 42 showeda good design results on the safety evaluation criteria. In other segments, the actual annualcrashes always exceed the predicted crashes.
Based on the current situations, suggestions could be:
1. The traffic volume in US Route 322 should be limited. From the Nbr calculation, wenoticed that AADT are directly related to the annual crashes. Also, from the analysis onthe Crash Data, the higher the AADT in certain segment, the more crashes happened inthat segment. The future design should consider adding more lanes to the original design.Since the increasing rate in vehicles is unlikely to shut down, adding more travellinglanes will release the current traffic pressure. Also it will satisfy the future traffic demandwithout any changes in the future.
2. The lane width needs to change. From the Crash Modification factors, one of the factorsis related to lane width. Even though the high AADT draw most of the answers to 1 anddid not seem to matter that much, if we successfully decrease AADT (HOW), lane widthwill be significant. Similar to the solution in first suggestion, adding more lanes willefficiently decrease AADT in each of the lanes. Also, new design should add corridors incertain sections and decrease the number of access points of Route 322.
3. The radius of the horizontal curves needs to be improved (HOW). From the AASHTOGreen book, the radius will cause changes in the Horizontal Curvature AMF. This willalso cause the rapid increase in crash rates. Future design should consider cut and fill incertain sections of the road way. Also, redesign some of the curves in the original design,especially those unsatisfied to the AASHTO requirements, will efficiently decrease thecrashes caused by sudden speed changes.
Speed Consistency Evaluation of Existing Conditions
For the Speed Consistency Evaluation, we used the geometric design data provided topredict operating speeds of the passenger cars and trucks along the US Route 322 studysection. After the evaluation, the geometric design consistency for the passenger cars was fairand the geometric design consistency for the trucks was poor. For a roadway if the design speedconsistency is poor or even fair on a roadway there needs to changes to that roadway. For thepassenger cars design consistency there was a total of 6 segments that may benefit from someimprovements. There were 2 segments that showed fair speed design consistency and the other 4showed good design consistency, but still show us some concerns with the drop in speed fromthe others. The segments showed fair design speed consistency for the main segment that need tobe changed first over the ones with good design speed consistency. For the truck designconsistency, there were a total of two spots where the speed consistency is poor. Since thosespots show up poor it makes the alignment poor because of how those spots will have trafficbacked up. These spots need to be the first ones fixed since of the traffic delay and problemcome from these bad design speed consistency spots.
Solving for the predicted operating speed of the passenger cars we first had to find the PCand PT’s of horizontal alignment data and vertical alignment data for US Route 322. Using thosestations, segments were created for both the eastbound and westbound routes. After creating thesegments, the regression equations were used from (Fitzpatrick et al. (1999)) to determine theexpected 85th percentile speed of the curve midpoint. Looking at the grades and where thecurves overlap each other on the segments to figure out which formulas went with whichsegment. For every tangent segment it was assumed to make its expected 85th percentile speed tobe 62.2 miles per hour instead of using equations to solve for it. After the 85th percentile speedwas found for every segment, each midpoint of each segment was found so we could graph the85th percentile speed of each segment versus the actual midpoint of the segment. In appendix Dshows the plot for both the east and west bound graph showing the roadway for both directionsshow fair speed design consistency.
Solving the predicted operating speed of the trucks was a little different in the sense thatonly the vertical alignment data was needed. With using a complex excel spreadsheet; thespreadsheet only needed the distance between the PVI’s of each curve and the beginning gradeof each curve to find the predicted speeds. Also, the design speed of 50 miles per hour was usedand the initial speed of 50 miles per hour. Instead of using the default weight/power ratio of 100it was decided to use a weight/power ratio of 150 to be more realistic weight of the trucks on thehighway. Since traffic in most areas of the roadway is 20% trucks, the weight/ratio of 150 willmore accurate with weight of truck to precise on the actual predicted operating speeds for thetrucks. In Appendix D shows the plot for both the eastbound and westbound graphs showing thespots of the roadway that have poor truck design speed consistency.
Environmental and Resource Inventory
The eight mile of corridor of Route 322 that stretches between Potter Mills (Junction SR-45) and Lemont (Junction I-99) has an extreme variety of environmental, commercial, residential,and agricultural features. All of these features have the potential to negatively affect the Route322 improvement project whether it is by increasing the cost of any potential improvements orcreating negative PR for the project due to increases in traffic noise.
To quantify the potential impact of each of these features we developed the followingranking system, in which items were categorized as either residential, commercial/communityasset, environmental, agricultural. With the exception of agricultural and undeveloped land thefeatures were then assigned an A-C rating where A is the highest priority for conservation and Cis the lowest priority for conservation.
Residential A - This category is reserved for the high density residential developments orhigh value homes. Due to the high cost of buying high value properties or disturbing multipleproperties these areas if disturbed would adversely affect the budget of the project. In additiondisplacing large numbers of residents would adversely affect the public relation portion of theproject.
Residential B – This category represents areas that are currently in the process of beingdeveloped. Since the properties have not been developed they would be cheaper to acquire inaddition to displacing a smaller number of families than a Residential A property.
Residential C – This category represents isolated homes that would have a minimalimpact on the project.
Commercial/Community A – This category represents items that would are consideredassets to the community and are not easily replaced. For the purposes of this project any itemclassified into this category is automatically preserved.
Commercial/Community B – This category represents items would be easier to replaceor relocate in the community such as little league fields of commercial businesses. Though itwould be possible to relocate such facilities they are still merited a high degree of priority forpreservation since affecting them would add significant cost to the project.
Commercial/Community C – This category was not used in the inventory for thisproject.
Environmental (A, B, C) – Due to the varied nature of environmental hazards thecategory was not subdivided. Hazards that were labeled in the environmental category consistedprimarily of wetlands, Floodplains and minor bodies of water both of which would have thepotential for only minimal impacts on the project. The impacts could be considered minimalsince relocating and remediating wetlands is a relatively common practice.
Agricultural/Undeveloped – This category represents the ideal area to develop sinceacquiring land in either represents a minimal monetary and public relations cost to the project.For the case of this project some consideration was given to following the existing property lineand natural barriers between properties. By following this practice it will minimize the amount ofland purchased as well as the number of access points that will need to be provided.
The results of this inventory can be seen in the attached Appendix E. In addition to theinventorying the environmental conditions of the corridor the attached appendix also depicts apotential alignment change that would allow for major upgrades, (conversion to a closed accesshighway), while preserving the maximum amount of high priority features along the corridor.
Recommended Design Improvements based on Existing Conditions Analysis
The first recommendation that is being proposed is the construction of a 322 expressroute that would bypass Business 322. This recommendation is illustrated in Appendix F; theproposed alignment would have a serviceability rating of A which is a considerable improvementcompared to the current under preforming route. Though this recommendation would have thehighest initial cost, it will provide the most permanent solution. With a design speed of 55 milesper hour and only two access points it would provide a seamless corridor to connect I-99 with theexisting section of SR 322.
In determining the exact alignment of this corridor many of the complex environmentalfactors surrounding the area had to be taking into account. As a way of quantifying this eachhazard was assigned a numerical value between zero and six indicating its level of importance.For example a golf course or high-density sections of homes would receive a rating of 6 and bycomparison a stretch of undeveloped land or farm land was awarded a zero. After this systemwas established three conceptual routes were evaluated a northern, southern, and a hybrid routeand then evaluated to which had the lowest environmental impact number.
In our case the lowest environmental impact number was scored by the hybrid route,which is the base for the route you see in Appendix F. As can be seen by the provided mappingthe alignment has only two access points at either end to merge traffic onto existing 322. Inaddition to the new alignment this proposal will also call for the realignment of SR144 whichcurrently forms a junction with 322 in the town of Potters Mills. In the proposed realignment thisjunction would be moved west so that the junction is on the west side of 322. Due to the limitedhorizontal space on either side of the alignment the berm in this area will vary between 30 andzero depending on the amount of available space. After it has left the eastern section it willswitch to a traditional rural berm of 30’ for the remainder of the route as it approaches statecollege.
In addition to the space constraints the eastern portion of this proposed alignment hassome of the more extreme topography in the corridor. These grade changes will be handed withthe most economical combination of cut, fill, and elevated bridges. As, an added function theseelevated bridges will allow many local roads to remain unchanged which ensures continuedaccess for local commuters and travelers. Though this recommendation delivers the highestpossible level of performance the following two other more economical recommendations wereevaluated so that they could be compared to the four lane bypass.
From the CAD drawings attached in the report, all the detailed design elements areshown. There are 11 horizontal curves and 14 vertical curves in the entire roadway. The requiredminimum design radius is 760 feet and minimum K values, which measure the changes of gradefor vertical curve, are 61 for crest and 79 for sag. All the design criteria are met in the new Four-lane highway design.
Recommendation 2 proposed the design and construction of a truck climbing lane. Thisclimbing lane is necessary due to the large traffic volumes which are composed of 17%-20%truck traffic. This will address the issue of queuing that currently exists as truck speeds decreaseby 10 plus mph. Not only will this help traffic flow but it will also decrease the possibility of rearend accidents due to approaching the queuing at a higher rate of speed.
One climbing lane will be installed east bound and two will be installed west bound on322. All approaches are 12:1 and end transitions are 60:1. Climbing lanes will terminate whentruck traffic attain a speed within 10 mph of other vehicles and at least 40 mph. The goal is tostart the transition when trucks get to 45 mph to ease the transition process. The East boundclimbing lane approach will start at station 590+50 and be in full transition at station 591+94until station 678+02. Station 678+02 will begin the end transition, which will end at 685+22.This lane starts at the first speed drop and is carried to the last speed reduction for consistency inthe roadway. The first West bound climbing lane approach will start at station 632+60 and be infull transition at station 631+16 until station 596+93. Station 596+93 will begin the end
transition, which will end at 589+73. The second climbing lane approach will start at station330+41 and be in full transition at station 328+39 until station 323+40. Station 323+40 willbegin the end transition, which will end at 316+20. See below for average travel speed andpercent time spent following improvements between existing and proposed.
TABEL 2: Comparison of No Climbing Lane Versus Climbing Lane
RT 322W/O ClimbingLane Climbing Lane Both
Segment Station ATS PTSF ATS PTSF LOS
WestBound 5487-6417
631+16-596+93 24.86 97.74 37.83 94.41 E
35870-36696
328+39-323+40 20.65 98.36 36.28 97.89 E
EastBound
33829-35005
591+94-678+02 24.86 97.74 37.83 94.41 E
During construction a temporary travel lane will be paved to construct the first climbinglane. Traffic will then sift to use one of the existing travel lanes and the new temporary lane. Thiswill give adequate room to construct and tie in the climbing lane to the existing. Traffic willthen shift to the new climbing lane and existing travel lane to construct and tie in the secondclimbing lane if lanes overlap.
See Appendix G for LOS calculations and truck speed profiles that contain climbing landinformation. Cross section drawings for climbing lanes can also be found in the Appendix D.
Another minor change is the reconstruction of part of the alignment. From station 470+00to 530+00, there existed an “S” shape curve in the original horizontal alignment. Based on ourspeed consistency and safety evaluation check, this design caused more crashes and speed dropthan other sections of the highway. So it was planned to redesign this portion of the road. Forthe redesign of the “S” shape curve the new alignment included three horizontal curves and fourvertical curves, which is shown in Appendix D. The alignment was drawn was the design speedof 55 miles per hour instead of 50 miles per hour like the original alignment. The change to thedesign speed was a precautionary measure for the roadway. With an alignment being designedwith a higher design speed it will be easier to see if the roadway is safer and has better speedconsistency. The higher the design speed the more risks there will be on the alignment. Also theminimum radius for the horizontal curve will larger for a design speed of 55 miles per hour thanthat of a horizontal curve with a design speed of 50 miles per hour. All three horizontal curvesare larger than the minimum curve radius of 960.3 feet and the width of each lane is 12 feet. Allfour vertical crest curves were designed with the K value of 114 and none of the grades for thevertical curves exceeded 5 %. The redesign that was chosen will have the least environmentalimpacts as other designs would have. The biggest environment impact the new alignment has is
the amount of earthwork that has to be done. Overall the new alignment for the “S” shape curveis a lot better than the original as can be seen in Appendix H. Appendix H shows the crashprediction data and speed consistency graphs that show good speed consistency for the newalignment.
The following design criteria are based on the assumption that Route 322 will beupgraded to a four lane limited access highway.
Design vehicle - Interstate Semitrailer [WB-67] Design vehicle with 53.0 ft. trailer as grandfathered in the 1982 Surface Transportation
Assistance Act Minimum Design turning Radius - 44.8 ft. Center line turning radius (CTR) - 41.0 ft. Minimum inside radius - 1.9 ft. Projected design traffic volume 20 years with 2.2% per year Between Jacks Mill Road and Elks Club Road - 19,959.1 Between Sharer Road and Wagner Road - 18,144.64 Between Dogtown Road and mountain Back/Red Mill Road- 16,934.99
The design speed chosen is 55 miles per hour because of how the existing four lanehighway runs into the proposed highway is 55 miles per hour. Also, criteria based on a ten milesper hour reduction from trucks.
The design K value for this highway is 114 The maximum vertical grade is going to be 5 % Superelevation - 8% Minimum radius of Curve grade - 8 % Minimum radius for horizontal curves - 960.3 ft. Lane widths 12 ft. Shoulder widths - median side 6 ft. and right side 10 ft.
Safety Evaluation of Design Alternatives
Safety Evaluation is essential for our four lane highway design. The original design gaveus a comparatively high crash prediction during peak hour, especially in the central part of theRoute 322—between Sharer Road and Wagner Road. There are two reasons for the highcrashing rate. First, two lane highway is a comparatively high accessing design. With an accesspoints/mile of 15, the vehicles running in the highway will consider more complex trafficsituations. Second, two lane highway need to consider more adjusting factors on the crashprediction, such as rumble strips, driveway density, superelevation and so forth. Based on thesecircumstances, our original safety from Appendix C, prediction has a total crash of 29.51 peryear. The highest crash in certain area reaches 1.1 per year.
After our four lane highway design established, several new traffic performance wasensured. First, four lane highway did not have any access points for the entire highway; thissignificantly decreased the crash potentials caused by vehicles entering the highway. Second, thesafety evaluation for four lane highway only engages with three adjusting factors, which reveals
the proficiency for this design. In the new safety evaluation from Appendix F, the total predictedcrash is only 12.61 for the entire highway. When comparing the corresponding sections, over70% of the sections are improved on the safety evaluation. This give us a positive attitude tocarry on our for lane highway design in the future.
Safety evaluation is also essential to check our horizontal alignment improvement for theS curve between Sharer Road and Wagner Road. Our design is planning to adjust the trafficchanges within this portion of roadway since it provide a comparatively worse speed consistencyand safety performance than any other sections of the Route 322.
The original safety evaluation is part of the safety evaluation on the last progress report.By tracing the horizontal stations, this section is from 470+00 to 540+00 from west to east. Byreferring to the original safety evaluation in Appendix D, the total crashes in this section are 4.66per year. The major issue in this section is this S curve. Based on the AASHTO Green Book, thedesign of the curve should consider the radius for curves and K values. In the former radius andK values check, the design value for this section almost surpasses the design criteria.Considering the access points in this section, the horizontal radius, vertical grade and road sidehazard rating, the predicted crashes are reasonably higher than other sections.
The ideal design is to redesign the horizontal alignment for this section. The newalignment will decrease the severe changes on the grade, so that the k values will become largerto satisfy the Kmin for design criteria. In addition, the new alignment will clear all the trivialcurves. The new safety evaluation in Appendix H for this section is optimistic. The total crashesper year decrease to 3.94. That is a good sign for this improvement.
Operational Evaluation of Design Alternatives
A speed consistency evaluation was done for the major recommendation 1 of the fourlanes divided highway and on the minor recommendation 3 of the redesign of the “S” shapecurve on the original alignment. For recommendation one, the truck speed consistency evaluationwas done for the east bound and the west bound truck traffic. The truck speed consistencyevaluation was done for the new four lane divided highway to see if there is any speed dropsover 6 miles per hour. If the alignment for the new four lanes divided highway has no speeddrops over 6 miles per hour than the alignment will have good speed consistency. In Appendix B,the speed consistency graphs for the truck speed profile will show that there are no speed dropsmore than 6 miles per hour for either the east bound or west bound direction. Since the graphsshow no speed drops over 6 miles per hour means for the west bound and east bound evaluationshow they both have good geometric design consistency. This is an improvement from theoriginal two lane highway because there were parts of the highway that showed the geometricdesign consistency to be fair instead of good like the new alignment, which is shown inAppendix C. Also there were a lot more drops in speed on the old alignment than the new fourlane highway. The graphs for the new four lane highway show a lot more consist travel speedswith only a couple of changes to speed consistency.
For recommendation three, the speed consistency evaluation was done for both thepassenger cars and trucks for the new alignment. In Appendix D, the graph for passenger car
speed consistency will show that the new alignment has good geometric design consistency. Thisis an improvement from the original “S” shape curve alignment. There are around the samenumber of speed drops for both alignments but the speed drops for the new alignment havesmaller speed drop values. The truck speed consistency evaluation showed a good speedconsistency also for the new alignment which can be seen in Appendix D. This is also animprovement from the past truck speed consistency evaluation which had some spots of fairspeed drop consistencies. The improvement is especially seen in the west bound truck speedconsistency which had the worst speed drops on the original “S” curve. The new alignment ofthe “S” curve showed to have better speed consistencies for both the passenger and truck profilesfor either direction.
The HCS software gives us a similar prediction on the safety evaluation. Referred fromAppendix F, the original two lane highway have a level of service of D for the passenger cars, ifconsidering passing lane influence, the level of service will drop to E. The major reasons for thislow performance are the same as the safe evaluation part. Once the four lane highway design isestablished, the level of service is A. The clearance of access points and other safety issues weneed to consider provide a predictably optimistic result on the level of service. This resultsupported the development of the four lane highway.
Recommended Design Improvement
Based on the all the recommended designs, the benefits and costs are listed and comparedfor future development. The four lane highway design should be the most suitable and efficientrecommendation. This design will clear most of the influence from the surrounding environment.Most of the unsatisfied vertical and horizontal curves are redesigned and provided a smoothergrade change and horizontal curve change. Furthermore, on the safety evaluation and speedconsistency check, four lane divided highway provide an optimistic result. The total predictedcrashes per year are decreased from 29.51 to 12.61, and over 70% of the sections are improved.In the two lane highway design, the speed drop surpassed 6 miles per hour in the Jacks MillRoad and Elks Club Road section and Dogtown Road and mountain Back/Red Mill Road section,after the new design applied, there is no speed drop than 6 mile per hour in either east or westbound. Also, since the four lane highway will eliminate all the access points to the highway, themobility will be effectively ensured. From the level of service comparison, the new designchanges the overall level of service from D to A.
The two minor changes also provide considerably effective improvement in certainsections. For the climbing lane design, the original speed drop for the trucks in there sections are10 plus miles per hour. Based on the Average Total Speed (ATS) and Percent Time-Spent-Following (PTSF) calculated, the level of service in these sections of road is only E. After theclimbing lanes are applied, the PTSF is decreased for 1.7 percent averagely for all the sections,and ATS is increased for 13 mph for all the sections.
For the horizontal alignment changes for the S curve in Sharer Road and Wagner Roadsections, the original road way section provide a poor safety evaluation and speed consistencyresults. The total crashes for this section is 4.6 per year, and the speed drop for this section isover 10 mile per hour for trucks and a 3 mile per hour drop in the east bound and 7 mile per hour
drop in the west bound for passenger cars. After the new alignment is applied, the predictedcrashes decreased to 3.94 per year. The speed drop for trucks decreased to 2.5 miles per hour andspeed drop for passenger cars decreased to 1.6 miles per hour.
Having considered all the benefits and cost it will provide for all the recommendations,the major recommendation will be adopted and developed in the future. Four lane highway canprovide the most direct and efficient changes for Route 322. Also, four lane divided highwaywill improve 322 for the entire scale rather than just improve portion of this highway, so that itwill benefit for future traffic volume increasing.
Pavement Design for Recommended Alternative
Pavement design is the most essential portion for our four-lane highway design. Thedetailed design procedures are based on the AASHTO Green Book. For the rigid pavementdesign, groups should assume a 20 year design life. For the flexible pavement design, a 10 yeardesign life was assumed. A three-inch surface course overlay at year 10 and year 15 werecompleted to reach a 20 year design life. The equivalent single axle loads (ESALs) were givenfor a 5-axle semi-tractor trail to be 2.33 and 2.4 for flexible and rigid pavement respectively.The ESALs were then multiplied by 210 trucks as 210 was the base year truck traffic todetermine the ESALs in a given day. Next, the ESALs per day were mulipied by 365 days todetermine the total ESALs per year. The following equation was used to expand the total ESALsfrom year 1 to year 10, 15 and 20: ESAL at year # = Truck/per (yr1)*1.022^ (yr#). Refer toAppendix I for pavement design. Corresponding design monographs were used for flexiblepavement to determine the structural number (SN) and rigid pavement to determine the slabdepth. The following information was used to determine the SN of 5 and slab thickness of 8”:Concrete Modulus of Rupture (S’c) = 630 lb/in2; Concrete Elastic Modulus (Ec) = 4 x 10^6 lb/in2;Subgrade Reaction Modulus (k) = 160 pci; Standard deviation (rigid)(S0)= 0.35; Standarddeviation (flexible) (S0) = 0.45; Load transfer coefficient (J) = 3.2; Drainage coefficients (M orCd) = 1.0; CBR = 8; PSI = 4.2; TSI = 2.5; ΔPSI = 1.7; Reliability (R) = 90%; Minimum surface(wearing course) thickness for flexible pavement = 4 inches.
Calculations were completed to determine the construction cost of both flexible and rigidpavements. Flexible pavement contains three layers (wearing, base and subbase). The depth ofthe layers were dependent the SN and cost. Preliminary depths were ran to determine the totalcost per yd²/inch thick. The cheapest combination of surface course ($2.82 yd²/inch thick), hotmix asphalt base course ($4.25 yd²/inch thick) and No. 2A subbase course ($1.17 yd²/inch thick)was used. That combination is a 5” wearing course, 5” hot mix asphalt base course and 8” No.2A subbase course. The total cost for flexible pavement is $113,120,945.25, while rigidpavement is $123,879,520.36. From this analysis, the flexible pavement was chosen to constructUS Route 322 as it is roughly $10.76 million cheaper. Refer to Appendix J for construction cost.
Construction Cost Estimate for Recommended Alternative
Referring to Appendix J for what follows in this section, it shows all of the calculationsmake up the construction cost estimate for the recommended alternative. The calculations start
off with the overall length of the new roadway and the total length of the Jersey Barrier on theproject. Then it shows the total amount of inlets, concrete piping, and box culverts (10’x7’).After finding the total quantities for each one, the cost was calculated using the unit cost sheetprovided from lab.
Next, was to calculate the flexible and rigid pavements to figure out which one was thecheapest. For the flexible pavement the thickness of the wearing, base, and subbase wasaccounted for along with the total area of the new four lane divided highway. The cost per unitwas once again pulled from the sheet given in lab and the costs for all three parts of the flexiblepavement were calculated. Also, the 10 year overlay and the 15 year overlay were calculated forthe flexible pavement. The overlay years were calculated because that is the typical lifespan andtreatment time for flexible pavement. Then for the rigid pavement the slab thickness and the subbase were accounted for along with the total area again. The cost per unit for rigid pavement wastaken from the handout from lab. There was no need for an overlay for the rigid pavementbecause the lifespan for it is 20 years.
The next quantity that needed to be calculated was the bridges that were needed along thenew four lane divided highway. There were a total of eleven bridges along the new highway andall of the lengths were found using the CADD drawings. The width for each bridge was found tobe 30 feet and all the areas of the bridges were calculated. The cost per unit of the bridge was175 dollars were coming from the handout from lab and an individual cost for each bridge wascalculated. Then the individual cost of each bridge was added to the total prices of the flexibleand rigid pavement. Finally, the cut and fill of the project was calculated and the total cost ofeach bridge was also calculated. This includes the amount cost of the right-of-way that will betaken up by the new four lane divided highway. We used vacant rural land cost when calculatingthe right-of-way cost. Then all of those costs were added the recent total cost of the flexible andrigid pavements. For this project the total cost for flexible pavement was $113,120,945.25 andthe total for rigid pavement was $123,879,520.36. In conclusion, the flexible pavement for thenew highway is cheaper than the rigid pavement.
Benefit-Cost Analysis for Recommended Alternative
AASHTO User and Non-User Benefit Analysis for Highways wizard will provide aconvenient way to calculate the Benefit-Cost Analysis for the entire project. In the ConstructionCost Section above, all the criteria for construction cost are already obtained. However, there ismore inputs need to be clarified and checked to begin the software calculation. In the appendix,all the input items and their values are shown. Based on the AASHTO Red Book, most of thevalues are set based on correlating criteria.
However, the Four-lane highway project has its own characteristics on some input itemsso that some of the values are changed. These values are explained in the following paragraphs.
For input No. 26, Base Case accident data and No.30, Improved Case accident data, theannual crashes are measured and calculated based on the real situations. The annual crashesfor Two-lane highway are measured from the original data and Four-lane highway is calculatedfrom safety evaluation.
For input No.20, cost estimate, the project cost is recalculated based on the followingaspects:The detailed data is shown on the Table 3 attached in the Appendix. Based on our calculation,the Right-of-way cost is $19,312,986.24 and construction cost is $113,120,943.25. The rest ofthe cost values remain default number.
For No. 21, accident data, based on our assumption, the Four-lane highway did notengage with too much construction stuff. As a result, the property damage decreased to 3, injurydecreased to 3 and the fatality is totally avoided.
For No.24, base case traffic data and No. 28, improved case traffic data, the defaultnumber are not useful. The daily two-directional traffic volume is 13,746 vehicles/day for baseand 19,959.1 veh/day for improved case. And the free-flow speed is 50 mph hour for base and 55mph for improved, instead of 60. These changes are based on our measurements on Route 322for these years.
For No. 25, base case user class data, the percentage of passenger cars and trucks areslightly different from the default number, specifically, 81% for PCs and 19% for trucks.
There are several assumptions on the input tabular.
1. The first assumption is on accident data on construction. Our assumption is based on thegeneral performance and data observed for Four-lane highway. There is very few accidentscaused by Four-lane highway construction since most of the construction will occur withouttraffic. Only if the new 4-lane construction is finished will the traffic happen.
2. The second assumption is in No.27, Annual agency operation costs for the base year. Forthe length of U.S. Route 322, a total cost of $120,000 is a fair estimate.
3. The third assumption is on Annual agency operating costs for the opening year. The snowremoval is $100,000. $70,000 is planned for Guardrail, Pavement Deficiency, and PavementDrop off, vegetation control, litter, drainage, signs and pavement marking. These numbers arejustifies on the general situations of the project.
4. The fourth assumption is terminal value. $0 is assumed for the value of the projectbrought at the end of its service life.
5. The fifth assumption is for K-factors and D-factors. From the real situation data, K=0.135and D=0.6.
Once all the inputs are obtained or calculated, they can be plugged into theRedbookWizard to calculate the outputs. From the final summary results, positive performance isshown in most of the aspects. The user value of time benefits is $408,572,516, which is aconsiderably high value. This reveals a huge amount of time will be saved for vehicles travelingin this road in the future. Also, the operating and operational savings is $86,434, the accident
savings is $52,926,624. The huge number savings in accident field will be good news for thisproject, since people will always prefer to drive in a safer highway. The total user costsassociated with the Four-lane highway is $ 118,101,106
Compared to the user costs, the Four-lane highway provides total user benefits of$460,341,231. The net benefits are $342,240,125 and the benefit-cost ratio is 3.898. This revealsthat the Four-lane highway will provide more benefits than the existing conditions.
Summary
The existing traffic issues were analyzed on U.S. Route 322, PA Route 144 and PA Route45. Route 322 currently provides inadequate flow with its current volume of traffic. Areas ofthe existing roadway also provide fair design consistency for passenger cars while poor designconsistency for trucks in the same stretch of roadway. Other areas of the alignment pose unsafemaneuvers that could be removed. Addition capacity consideration, safety improvements andnon-traditional transportation alternatives are primary considerations when designing theproposed recommendations.
Various features such as radii, k-values, safety and speed consistency evaluations ofexisting 322 were evaluated between Boalsburg and Potters Mills. During this time multiplerecommendations were made to handle the traffic growth rate of 2.2% annually. Theserecommendations were then reduced to 3 and AADT values were projected for 2034. The 3recommendations are as followed.
Recommendation 1 proposed a four lane divided highway. This alignment was based onpreliminary environmental inventory and priorities avoiding existing development andenvironmental hazards.
Recommendation 2 proposed the design and construction of a truck climbing lane. Thiswas determined from the evaluation of the truck speed profile in both east and west bound lanesas truck traffic consists of 17%-20% of the total traffic. The justification of the climbing wascompleted in Deliverable 1.
Recommendation 3 proposed the removal of an S-bend in the existing horizontalalignment. This recommendation was based on a drop in speed consistency and an increase ratein accidents at this point of the alignment.
Furthermore, design controls and criteria were discussed and recommendations weredesigned to this criterion. The design speed was determined to be 55mph due to connecting oldfour lane alignments to the proposed alignment.
Data was then collected to and evaluated of the general traffic performance of U.S. Route322. Based on the results, the three recommendations were designed to improve the safety andefficiency of US RT 322. Essential evaluations, including safety evaluation, speed consistencycheck, HCS software check, climbing lane performance check were applied for certainrecommendations in order to reach a detailed prediction for future performance. After all theevaluations, the three recommendations were weighed based on the benefits and costs they
provided in the future. In the end, four lane divided highway was finally adopted as the futuresolution to carry through to final design.
The construction cost is then calculated based on the planning design. The followingcriteria are considered in the construction cost:
1. Elementary construction facilities, this includes Jersey barriers, inlets, concretepipes and 10’x7’ box culvert.
2. Pavement construction, this includes flexible pavement and rigid pavement.Different categories on pavement will meet different traffic situations and designconstants.
3. Bridge construction, there is a consistent design for all the bridges required. Costis predicted based on the length of the bridge.
4. Excavation cost, the new Four-lane highway required cut and fill to improve theconsistency of the roadway, and the new cost is calculated based on the overallroadway scale.
With all the cost and benefit calculated, the ASSHTO RedBookWizard will be applied toreach the benefit-cost analysis. All the required inputs are evaluated. Some of them arecalculated based on the actual traffic conditions of Route 322, others are the AASHTO defaultvalues. The final benefit-cost analysis is attached in Appendix L. the Four-lane highway providestotal user benefits of $460,341,231. The net benefits are $342,240,125 and the benefit-cost ratiois 3.898. Other detailed criteria are all performed in positive ways in the final analysis. Theresults proved that Four-lane highway design will be an effective solution for the current trafficproblems. Also, it will be a beneficial design for future transportation demand in Pennsylvania.
APPENDIX AIntersection Turning Movement Count Data
US Route 322 and Wagner Road
US Route 322 and Taylor Hill Road
Note: Vehicle through movements along US Route 322 at Taylor Hill Road intersection must bederived from Wagner Road data.
US Route 322 and Neff Road
US Route 322 and Mountain Back/Red Mill Road
US Route 322 and PA Route 144
Appendix B
K-value and Radius Evaluation
Appendix CSafety Evaluation (Existing Alignment)
Safety Evaluation
Appendix DSpeed Consistency (Existing 322)
Passenger Cars
Trucks
Appendix E
Environmental and Resource Inventory
Appendix F
Major Change: Four-lane Highway
Safety Evaluation for Four-lane Divided Highway
Speed Consistency for Four-lane Highway
HCS Evaluation for Two Lane (Existing 322)
HCS Evaluation for Four-lane Divided Highway
Appendix G
Climbing Lane
LOS No Climbing Lane
LOSWith Climbing Lane
East Bound Climbing Lane
Details
West Bound Climbing Lane
Details
Appendix H
New Horizontal Alignment Design
Safety Evaluation for New Horizontal Alignment Design
Original Design
New Design
Speed Consistency of Passenger Cars for New Horizontal Alignment Design
Original Design
Eastbound
Westbound
New Design
Eastbound
Westbound
Speed Consistency of Trucks for new horizontal alignment design
New Design
Appendix IPavement Design
Appendix JConstruction Cost
Appendix K
Inputs for RedbookWizard
Input items and values for wizard
Input Item Value
Number of segments to analyze 1
Year construction begins 2014
Year operation begins 2018
Last year of analysis period 2034
Base year 2014
Name of User Class 1 PCs
Name of User Class 2 Trucks
Vehicle Type for User Class 1 All cars
Vehicle Type for User Class 2 All trucks
Vehicle Occupancy for User Class 1 (persons) 1.50
Vehicle Occupancy for User Class 2 (persons) 1.05
Value of Time for User Class 1 (base-year dollars) $16.50
Value of Time for User Class 2 (base-year dollars) $24.85
Fuel Cost for User Class 1 (base-year dollars per gallon) $3.67
Fuel Cost for User Class 2 (base-year dollars per gallon) $3.96
Percent of Operating Costs that are fuel (percentage points) 13.00
Real discount rate (percentage points) 4.00
Inflation rate (percentage points) 2.00
Financing rate (percentage points) 2.00
Financing term (years) 10.00
Issuance cost (% of amount financed) (percentage points) 5.00
General traffic growth rate (percentage points) 2.20
Annual Growth of Value of Time (percentage points) 1.50
Average Truckload Value (base-year dollars) $50,000
Market Interest Rate for truckload value (percentage points) 6.00
Average Commercial Cargo Value (base-year dollars)
Market Interest Rate for Commercial Cargo Value (percentagepoints)
Cost per property damage accident (base-year dollars) $3,900
Cost per injusr accident (base-year dollars) $138,100
Cost per fatal accident (base-year dollars) $3,723,700
Name of Construction Management Alternative 1Four Lane US322
Choice to proceed with extension
Segment input items and values for wizard
Input Item Value
Names given to segments US Route 322
Functional Class of each segment Rural otherprincipal arterial
Improvement Type for each segment Additional lanes
Segment Length without improvement (miles) 7.14
Segment Length with improvement (miles) 8.70
Base peak-direction, peak-hour volume (PCE per hour) 13746.00
Base peak-direction capacity (PCE per hour) 1700.00
Base Free Flow Speed (miles per hour) 50.00
Base Property-Damage Only Accidents (with base-year volume)(accidents per year)
12.8000
Base Injury Accidents (with base-year volume) (accidents per year) 13.6000
Base Fatal Accidents (with base-year volume) (accidents per year) 0.8000
Base Operating Cost (base-year dollars) $120,000
Improved peak-direction, peak-hour volume (PCE per hour) 19960.00
Improved Capacity (PCE per hour) 3400.00
Improved Free Flow Speed (miles per hour) 55.00
Additional peak hour change in delay (hours per vehicle)
Highest exponent on volume
Improved Property-Damage Only Accidents (with opening-year volume)(accidents per year)
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