Geometric Review and
Design (GRAD)
Cross Sections
5
52 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Understand the
elements comprising
the roadway cross
section
▪ Recognize the grading
options outside of the
roadway limits
▪ Understand the various
barrier options
available
Learning Objectives
53 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Section 301
▪ Assists the designer in determining lane and shoulder width and pavement cross slope.
▪ Number of lanes required is determined through use of capacity analysis
▪ Pavement type determined by volume and composition of traffic, soils, availability of materials, initial costs, maintenance costs
Roadway Criteria
54 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
The Typical Section
Traveled WayMedian Backslope
Shoulder –treated and
graded
Foreslope and Ditch
55 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Lane Width (Sect 301.1.2)
▪ Lane width in RURAL areas is dependent upon functional classification, traffic volumes, and design speed
▪ Refer to Section 105.3 for the National Network** lane width requirements
Pavement
** National Network is comprised of all Interstate Routes and Federal Aid Primary Routes – refer to TIMS for locations
56 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Lane Width (Sect 301.1.2)
▪ Lane width in URBAN areas is dependent upon functional classification and locale
▪ Refer to Section 105.3 for the National Network lane width requirements
Pavement
57 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Traveled Way widening on curves
(Sect 301.1.3)
▪ Used to accommodate WB-62 truck tracking
▪ Based on design speed, curvature, and traveled way width
▪ Placed on inside of curve
▪ Develop within the superelevation transitions
Pavement
58 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Pavement Transition / Taper
Rates (Sect 301.1.4)
▪ High Speed (≥ 50 mph)
▪ 𝐿 = 𝑊 𝑥 𝑆
▪ Low Speed (< 50 mph)
▪ 𝐿 =𝑊 𝑥 𝑆2
60
▪ Transition length for INCREASES in Traveled Way maybe more abrupt (i.e. 5:1 ratio)
Pavement
L = Taper Length (feet)
W = Offset width (feet)
S = Design Speed (mph)
59 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Pavement Cross Slope (Sect 301.1.5)
▪ Normal Crown (NC) = 0.016 ft/ft
▪ Can increase to 0.02 ft/ft
▪ Drainage issues or pavement type
▪ 3 or more lanes sloped in same direction on high speed roadway –
first two lanes sloped at 0.016; additional lanes are at 0.02
Pavement
510 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Pavement Cross Slope (Sect
301.1.5)
▪ Example Problem
Pavement
511 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Pavement Cross Slope (Sect
301.1.5)
▪ Example Problem
Pavement
512 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Pavement Cross Slope (Sect
301.1.5)
▪ Example Problem
Pavement
513 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Pavement Cross Slope (Sect 301.1.5)
▪ General Guidance:
▪ Crowns located between lanes (on a lane
line)
▪ 3 or 4 lane roadways, lanes can be
sloped in same direction as shown in
previous example
▪ Undivided roadways – crown at the
middle (even number of lanes) and at
the left or right edge of center lane (odd
number)
▪ Narrow raised median sections crowned
to outside as much as possible
Pavement
514 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Adjacent to Traveled Way
▪ Used to accommodate stopped
vehicles, emergency use,
maintaining traffic during
construction, lateral support of
the pavement, and to generally
improve the safety of the
highway
▪ Available for pedestrians and
bicyclists
Shoulders
515 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Definitions (Sect 301.2.1)
▪ Graded Shoulder Width – The area located between the edge of traveled way and the foreslope begin point
▪ Treated Shoulder Width – The portion of the graded shoulder which has some type of surface treatment
Shoulders
516 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Types (Sect 301.2.2)
▪ Paved
▪ Bituminous surface treated
▪ Stabilized aggregate
▪ Turf
▪ Refer to Pavement Design Manual
(Office of Pavement Engineering) for
structural design of shoulders and
shoulder typical sections
ShouldersPaved
Bituminous Aggregate
Turf
517 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Width (Sect 301.2.3)
▪ Shoulder widths in RURAL areas
vary depending on functional
classification, traffic, and locale.
▪ High truck volume could
necessitate wider shoulders
▪ If Treated Shoulder width is
increased, Graded Shoulder width
should be increased by the same
amount (MOT condition typically)
▪ Treated Shoulder width can be
reduced without impacting Graded
Shoulder width
Shoulders
518 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Width (Sect 301.2.3)
▪ Shoulder widths in URBAN areas vary depending on functional classification and locale.
▪ For ADTs of 400 or less, may
be beneficial to use
AASHTO’s Guidelines for
Geometric Design of Very
Low-Volume Local Roads
publication
Shoulders
519 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Width (Sect 301.2.3)
▪ Sometimes a wider paved shoulder is provided for MOT or to accommodate HSSD.
▪ Paved shoulder width reduction of less than 2 feet (at signs or lighting) will not require design exception; 4-foot minimum lateral clearance must be provided
Shoulders
520 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Right Turn Lane (Sect
301.2.3.1)
▪ Desirable to maintain the required mainline shoulder width throughout the length of right turn lane
▪ Shoulder may be reduced, but to no less than 4 feet paved and 6 feet graded (constrained R/W limits and low truck volumes)
Shoulders
521 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Shoulder Taper Rate (Sect
301.2.3.2)
▪ 25:1 should be used to reduce the shoulder width
▪ Transition length for INCREASES in shoulder width maybe more abrupt (i.e. 5:1 ratio)
Shoulders
522 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Shoulder Cross Slope (Sect
301.2.4)
▪ Depends on the shoulder type and pavement cross slope
▪ If the bridge shoulder cross slope is different than the approach roadway shoulder cross slope, then the transition shall occur on the roadway section (off of bridge and approach slabs) within a distance of 100 feet.
Shoulders
523 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Shoulders
524 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Shared Lanes (Sect. 308.3) and Paved
Shoulders (Sect. 308.4)
▪ Lane width of shared bicycle/vehicle lanes should be 14 feet minimum
▪ When utilizing paved shoulders on uncurbed roadways, provide minimum 4-foot wide shoulders
▪ Provide 5-foot wide shoulders to the face of vertical obstructions such as guardrail, curb or other roadside barrier
▪ Refer to Multi-Modal Design Guide *
Bicycle Facilities
*currently in development
525 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Bicycle Lanes (Sect. 308.5)
▪ Along two-way streets, should be provided on both sides to discourage wrong-way use.
▪ Along one-way streets, should be on the right-hand side of the roadway unless significant number of left-turning bicyclists or large number of potential conflicts (drives, sidestreets, etc.) on the right side.
Bicycle Facilities
526 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Bicycle Lane Widths (Sect.
308.5.4)
▪ Minimum lane width is 4 feet; 5 feet against curb/vert surface
▪ Preferred lane width is 5 feet
▪ Adjacent to a parking lane, a wider bicycle lane (6-7 feet) provides space to avoid impacting opening vehicle doors
▪ Areas of high bicycle use, width of 6 to 8 feet is preferred to promote side-by-side riding
Bicycle Facilities
527 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Section 702
▪ Multi-use paths designed primarily for
use by bicyclists and pedestrians;
physically separated from vehicular
traffic by an open space or barrier
▪ Fall under accessibility requirements
of the ADA
▪ Paths within public R/W that function
as sidewalks should meet PROWAG
guidelines
▪ Paths outside of public R/W should
meet ANPRM draft guidelines
Shared Use Paths
528 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Elements of Design (Section 702.2)
▪ Determine the Design User
▪ Width – min of 10 feet for two-directional path;
widths generally range from 10-14 feet
▪ Design Speed – 18 mph is typical
▪ Horizontal Alignment – “lean angle” method
should be used
▪ Cross Slope – 2% maximum
▪ Grade – shall not exceed adjacent roadway; 5%
when not adjacent
▪ SSD – eye height = 4.5 feet; object height = 0
inches
Shared Use Paths
Horizontal Alignment –Lean Angle Method.
529 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Sect 302.1
▪ Provides overall bridge
dimensions
▪ Width
▪ Lateral clearance at underpasses
▪ Vertical clearance over roadways
▪ Defined by the scope of work
being completed for the bridge
▪ Refer to Bridge Design Manual for
additional design information
Bridge Criteria
STRAHNET Requirement of 16 ft for military
530 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Bridge Criteria
This definition is required because of a federal requirement tied to funding
531 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Bridge Criteria
532 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Sect 303
▪ Composed of various elements
▪ Ramps
▪ One and two-lane directional roadways
▪ Accel/Decel lanes
Interchange Elements
Acceleration lane
Single-lane ramp
One-lane directional roadway
Deceleration lane
Multilane ramp
533 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Shoulder Widths to use on ramps –
1-lane vs 2-lane
▪ Look at the number of lanes on the ramp that engage the mainline
▪ Single-lane exit that widens to a multi-lane ramp – use single-lane ramp shoulder widths
▪ Multi-lane entrance ramps that reduce to a single lane by the entrance gore – use single-lane ramp shoulder widths
Interchange Elements – A Common Mistake
534 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Sect 304
▪ Portion of highway separating opposing
directions of the traveled way
▪ Principal functions
▪ Prevent interference of opposing traffic
▪ Provide a recovery area for errant vehicles
▪ Provide areas for emergency stopping and left-turn lanes
▪ Minimize headlight glare
▪ Provide width for future lanes
Medians
535 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Width (Sect 304.2)
▪ The distance between the inside edges of the traveled way
▪ Depends upon the type of facility, cost, topography, and right-of-way
Medians
536 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Rural Width (Sect 304.2.1)
▪ In flat or rolling terrain, desirable
median width is 60-84 feet.
▪ 84-foot wide median allows for a future
12-foot wide lane in each direction,
resulting in a 60-foot wide median.
▪ Minimum median width is normally 40 feet
▪ In rugged terrain, 10-30 feet median
widths may be used.
▪ Constant-width medians not necessary
▪ Independent profiles can be
established for the two roadways
Medians
537 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Rural Type (Sect 304.3.1)
▪ Normally depressed to a swale in the center
▪ Typically constructed without curbs
Medians
538 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Urban Width (Sect 304.2.2)
▪ Barrier medians are normally used in urban areas
▪ Dependent on the width of the barrier and the shoulder width required in Figure 301-4.
▪ Minimum widths▪ 10 feet (4-lane urban freeway)
▪ 22 feet (6-lanes or more urban freeway)
▪ Do not take into account extra width needed for median piers; may require a design exception if not able to widen median throughout the section.
Medians
539 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Urban Type (Sect 304.3.2)
▪ Type depends on traffic volumes,
speed, degree of access, and available
right-of-way.
▪ Median consisting of a TWLTL is
desirable on major streets with
numerous business drives
▪ 6-inch high concrete median, minimum
width of 4 feet, may be used on low-
speed roadways; increases safety by
eliminating left turns
▪ Barrier medians are normally
recommended for high-speed roadways
Medians
540 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Sect 601.2
▪ Based on the ADT and the Median Width
▪ Guidance is provided regarding whether a barrier should be evaluated, whether it is optional, or whether it is not normally considered
Median Barrier Warrants
541 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Sect 305
▪ Used mainly in low-speed urban areas
▪ Reasons to justify use of curbs/curbs
and gutters:
▪ Where required for drainage
▪ Where needed for channelization, control of access, or to improve traffic flow and safety
▪ To control parking where applicable
▪ To reduce right-of-way requirements
Curbs
542 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Types of curbs (Sect 305.2)
▪ Refer to SCD BP-5.1 for approved curb types:
▪ Type 1 – used mostly for temp situations
▪ Type 2, 2-A, 2-B, 6 – widely used along edges of traveled way in urban areas on low-speed roadways
▪ Type 3, 3-A, 3-B; Type 4, 4-A, 4-B, 4-C – used for channelization islands and occasionally along medians
▪ Type 7 – protection at bridge approaches
▪ Type 9 – used along truck aprons in roundabouts to assist trucks with an easier path through the roundabout and to help prevent truck overturns
Curbs
543 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Position of curbs (Sect 305.3)
▪ Low Speed Urban
▪ Curbs should be offset at least 1 foot and preferably 2 feet from the edge of traffic lane
▪ High-Speed Roadways
▪ Curbs should be avoided because of hydroplaning and vaulting concerns
▪ If used, should be placed at edge of treated shoulder or no closer than 4 feet from traffic lane, whichever is greater
▪ Height should not exceed 4 inches
Curbs
544 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Curbs
545 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Curb/Guardrail Relationship (Sect 602.1.5)
▪ Face of MGS guardrail should be located within 6 inches behind the face of the curb; high-speed roadways, preferably located so the face of guardrail is at the face of the curb.
▪ If guardrail cannot be placed within 6 inches for speeds under 50 mph, then it should be installed well behind the 6 inch curb (4 to 12 feet)* to allow vehicle suspension to return to normal state
Curbs
* Applies to MGS Guardrail (new standard guardrail) and not Type 5 guardrail (old standard).
Refer to Section 602.1.5 for guardrail offsets when curb is used.
546 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Curbs
547 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Operational Offset(Sect 600.2.3)
▪ Minimum offset of 1.5 feet (3 feet at intersections) is required behind the face of curb.
▪ This is necessary to:
▪ Improve driveway and horizontal sight
distance
▪ Improve travel lane capacity
▪ Reduce travel lane encroachments from
occasional parked or disabled vehicles
▪ Minimize contact with vehicle-mounted
intrusions (mirrors), car doors, and
overhang of turning trucks
Curbs
548 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Key Terms
▪ Clear Zone – The unobstructed, traversable area provided beyond the edge of the through traveled way for the recovery of errant vehicles. The clear zone includes shoulders, bike lanes, and auxiliary lanes, except those auxiliary lanes that function as through lanes
▪ Foreslope – The slope from the edge of the graded shoulder to the bottom of the ditch (also called fill slope)
▪ Backslope – The slope from the back of the ditch to the existing ground surface (sometimes referred to as the cut slope)
Grading and Sideslopes (Sect. 307)
549 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Key Terms (cont.)
▪ Non-Recoverable Slope – A slope that a vehicle can traverse, but it is generally too steep to allow the vehicle to stop or return to the roadway. Traversable non-recoverable slopes are between 1V:4H and 1V:3H and are NOT included in the specified clear zone distance.
▪ Recoverable Slope – A slope where a motorist may retain or regain control of a vehicle. Slopes flatter than 1V:4H are generally considered recoverable
▪ Critical Slope – A slope that is steeper than 3:1 on which vehicles are likely to overturn
Grading and Sideslopes (Sect. 307)
550 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Key Terms (cont.)
▪ Recoverable Ditch – A rounded ditch having a radius of either 20 or 40 feet
▪ Normal Ditch – A trapezoidal-shaped ditch having a bottom width of 2 feet and a rounding of 4 feet
▪ Roadside ditches are generally
categorized as traversable or
non-traversable.
Grading and Sideslopes (Sect. 307)
551 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Roadside Grading (Sect
307.2.1)
▪ Safety Grading – shaping of the roadside using 6:1 or flatter slopes within the clear zone area and recoverable ditches beyond the clear zone
▪ Used on interstates, other
freeways and expressways
Slopes (Sect. 307.2)
552 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Roadside Grading (Sect.
307.2.1)
▪ Clear Zone Grading – shaping of the roadside using 4:1 or flatter foreslopes and traversable ditches within the clear zone area
▪ Often used on high-speed rural
undivided facilities
Slopes (Sect. 307.2)
553 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Roadside Grading (Sect 307.2.1)
▪ Common Grading – shaping of the roadside using 3:1 or flatter foreslopes and normal ditches.▪ Used on undivided facilities
where the conditions for the use of safety grading or clear zone grading do not exist.
▪ Designer should ensure that all obstacles within the clear zone receive proper consideration/protection
Slopes (Sect. 307.2)
554 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Roadside Grading (Sect
307.2.1)
▪ Barrier Grading – shaping of the roadside when barrier is required for slope protection. Normally 2:1 foreslopes and normal ditch sections are used
Slopes (Sect. 307.2)
555 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Section 601.1.1
▪ Objects, or hazards, that if struck by a vehicle
can cause serious injury or death and should
be protected within the clear zone
▪ Bridge piers and abutments
▪ Culverts, pipes, and headwalls
▪ Non-breakaway sign/light support; utility poles
▪ Rough slopes in cut sections
▪ Ditches where head-on impact is likely
▪ Bodies of water
▪ Retaining walls/MSE walls/noise walls
Obstacles
556 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Goal of a highway roadside safety device is to assist in providing a forgiving roadside for an errant motorist.
▪ Contains or redirects the vehicle away from the hazard
▪ Decelerates the vehicle to a stop
▪ Readily breaks away, fractures, or yields
▪ Allows a controlled penetration
▪ Allows a vehicle to safely traverse the feature
Roadside Safety Devices (Sect. 603)
557 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Longitudinal Barriers (Sect.
603.1)
▪ Function by containing and redirecting impacting vehicles
▪ Flexible Cable Systems **
▪ Semi-Rigid Barriers
▪ Type 5 and Type MGS guardrail
▪ Deflects up to 5 feet; provide enough
offset behind guardrail to obstruction
▪ Rigid Concrete Barriers
▪ Single slope barrier
▪ Portable concrete barrier
Roadside Safety Devices
** only used in Ohio to prevent cross-median crashes
558 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Longitudinal Barriers (Sect.
603.1)
▪ Steel beam guardrail post spacing influences the deflection distance
▪ Anchored concrete barrier is not intended to deflect; PCB is expected to deflect
Roadside Safety Devices
559 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Long-Span Guardrail (Sect.
603.1.2.5)
▪ Requires 62.5 feet of MGS guardrail on both sides of the system
▪ All but the first 12.5 feet of an anchor assembly may be included in this value
▪ Deflects 8 feet; when over culvert, headwall should not extend higher than 2 inches above the ground line within this 8 feet
▪ Refer to SCD MGS-2.3
Roadside Safety Devices - Guardrail
560 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Guardrail Posts in Rock
Roadside Safety Devices - Guardrail
Locations where motion of the posts may be restricted
Should use steel posts
Refer to:
Report TRP-03-119-03
561 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Blockouts
▪ Connector between the post and the face of guardrail
▪ Standard is 12 inch blockout for MGS guardrail
▪ 12 inch steel plate may be used for additional clearance; not recommended when:
▪ Post spacing is reduced
▪ Wooden posts are used
▪ Guardrail is adjacent to curb
Roadside Safety Devices - Guardrail
562 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Anchor Assemblies (Sect. 603.3)
▪ End terminals along barrier; used to decelerate a vehicle to a safe stop or containing and redirecting the vehicle.
▪ Multiple types, based on need and function
▪ Refer to Section 603 and Standard Construction Drawings for when to use appropriate terminal assemblies and offset information
Roadside Safety Devices - Guardrail
563 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Anchor Assemblies (Sect. 603.3)
Roadside Safety Devices - Guardrail
Designers should consult the ORE approved products list for the most current information regarding proprietary safety devices.
564 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Design Considerations
▪ Barrier can impede sight distance, especially around driveways and approaching bridges
▪ Installing flared guardrail and
either terminating the end
outside of the clear zone or
burying it into a backslope to
avoid impacting sight distance
Roadside Safety Devices - Guardrail
565 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Offset
▪ Face of guardrail should be placed 2 feet off of the edge of the paved shoulder
▪ Grading
▪ Grading in front of and underneath the guardrail should be relatively flat with minimal changes in the slope
▪ Use 10:1 or flatter slope from edge of shoulder to the face of guardrail –refer to SCD MGS-5.2/5.3
Roadside Safety Devices - Guardrail
566 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Length of Need
▪ Tangent Alignments
Roadside Safety Devices - Guardrail
567 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Length of Need
▪ Curved Alignments
Roadside Safety Devices - Guardrail
568 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Roadside Safety Devices - Guardrail
569 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Design Considerations
▪ Make sure that the barrier is protecting something that is within the clear zone
▪ Guardrail can also be a hazard and should only be used where the results of leaving the roadway and overturning or striking a fixed object would be more severe than the consequences of striking the barrier
Roadside Safety Devices - Guardrail
570 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Roadside Safety Devices – Concrete Barrier
571 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
Roadside Safety Devices – Concrete Barrier
572 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Bridge Terminal Assemblies (Sect. 603.5)
▪ BTA Type 1 – commonly used to connect guardrail to concrete barrier or bridge parapet
▪ A single 10-gauge thrie-beam element may replace the nested 12-
gauge rail element
▪ BTA Type 1 Barrier Design – commonly used to connect barrier design guardrail or a Type 1 Impact Attenuator to a concrete median barrier
▪ BTA Type 2 – commonly used to connect guardrail to the trailing end of a concrete barrier or bridge parapet located outside of the clear zone of opposing traffic
Roadside Safety Devices – Bridge Terminal Assemblies
573 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Impact Attenuators
▪ Section 603.4
▪ Also known as crash cushions, used to shield motorists from rigid structures like bridge piers and end of concrete barrier
▪ 3 Types
▪ Type 1 – gating, re-directive, non-reusable
▪ Type 2 – non-gating, re-directive, re-usable
▪ Type 3 – low maintenance, re-usable, ideal
for use at locations of higher impact
frequency
Roadside Safety Devices – Impact Attenuators
574 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Design Considerations – Preferred
Order of Corrective Treatment
1. Remove the obstacle
2. Redesign the obstacle so that it can be safely traversed
3. Relocate the obstacle to a point where it is less likely to be struck
4. Reduce the impact severity by using an appropriate breakaway device
5. Shield the object
6. Delineate the object
Roadside Safety Devices
575 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Key Terms
▪ Traveled Way
▪ Traveled Way Widening
▪ Graded Shoulder
▪ Treated Shoulder
▪ Clear Zone
▪ Foreslope
▪ Backslope
Module Review
576 | Module 5 – Cross Sections
ODOT L&D Vol. 1 – Section 300
▪ Key Terms (cont.)
▪ Traversable Slope
▪ Recoverable Slope
▪ Recoverable Ditch
▪ Normal Ditch
▪ Safety Grading
▪ Clear Zone Grading
▪ Common Grading
▪ Barrier Grading
▪ Roadside Safety Devices
Module Review