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Designing for Nonmotorists

Off-Road Facilities

Part 2, Shared Use Paths: Designing for Nonmotorists

Presented at the FHWA Field Engineers Learning & Development Seminar
April 20, 2010, Dallas, Texas

Christopher Douwes, Trails and Enhancements Program Manager,
Federal Highway Administration


Off-Road Facilities: Shared Use Paths

Photo of a group of people attending opening day and dedication of the Lake Mineral Wells State Park and Trailway in Texas.

Photo from the National Transportation Enhancements Clearinghouse
Mineral Wells to Weatherford Rail-Trail, Mineral Wells, TX.
Opening day and dedication of the Mineral Wells to Weatherford Rail Trail.
(Photo: Texas DOT).

Course Overview

Part 3: Off-Road Facilities

  • Shared Use Paths

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Shared Use Paths: Surface

Surface: Firm and stable.

  • Must accommodate wheelchairs.
  • Accommodate narrow-tire bicycles.
  • Accommodate people pushing baby strollers (good "test equipment").
  • Slip resistance desired, but not required.*
    • * Required for public rights-of-way (PROW).
  • Pavement is not required. Pavement may not be appropriate in some settings (rural).

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Shared Use Paths: Surface

  • There are no Federal laws or regulations that require a shared use path to be paved.
Photo of equestrians riding and people walking along a trail. Photo of people walking and running along a trail.
Photo of people jogging and pushing a baby stroller along a trail. Photo of two women in Amish garb inline skating along a trail.
Photo of a person riding a bike passing and waving to a passing horse and buggy.

Photo source: Stuart Macdonald, American Trails: www.americantrails.org.
Top left: High Line Canal Trail, Cherry Hills Village, CO.
Photo by Stuart Macdonald, American Trails, www.americantrails.org/photoGalleries/cool/26-crusher-fines-rock-trail-surface-photos.html
Top middle: Town Lake Trail, Austin TX. Photo by Stuart Macdonald, American Trails.
Bottom left: High Line Canal Trail, Cherry Hills Village, CO. Photo by Stuart Macdonald, American Trails.
Bottom middle: Holmes County, Ohio. Source: Holmes County Park District / Holmes County Rails to Trails Coalition.
Right: Holmes County, Ohio. Source: Holmes County Park District / Holmes County Rails to Trails Coalition.

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Shared Use Paths: Surface

Graphic of a Rotational Penetrometer.

Firm and stable.

  • Some crushed aggregates can be firm and stable.
  • Rotational Penetrometer:
    Measures firmness and stability of ground and floor surfaces.

www.beneficialdesigns.com/surfaces/surface.html#rotational


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Shared Use Paths: Surface

Pavement

  • Asphalt or Concrete?
  • Asphalt often cheaper to construct, but may suffer water, frost, and tree root damage.
  • Concrete may be cheaper in the long run: may better withstand flooding, frost, roots, etc.
  • Concrete: use "saw cut" for joints.
  • Check for accessibility and a smooth surface.

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Shared Use Paths: Tread Obstacles

Tread Obstacles: Avoid, Minimize, and Prevent.

  • Prevent roots, rocks, ruts, bumps, cracks, etc.
  • Maintain a smooth path: sweep, fix irregularities.
  • Exception: Detectable warnings at crossings.

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Shared Use Paths: Gaps

Gaps: Avoid, Minimize, and Prevent.

  • Keep drainage grates off the trail.
  • Minimize: openings, pavement and bridge joints, open bridge decks, railroad crossings, boardwalks.
  • Openings shall not permit passage of a 0.5 inch / 13 mm diameter sphere.
  • Elongated openings should be perpendicular or diagonal to travel direction.
  • Some exceptions for boardwalks: 0.75 inch/19 mm.

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Shared Use Paths: Speed

  • Design Speed: AASHTO Guide is 20 mi/h.
  • Draft 2010 AASHTO Guide proposes 14 mi/h.
  • REASON: Most bicyclists are slower than the "design bicyclist", pedestrians, other users.
  • Consider not having completely straight paths:
    • May encourage excessive speed.
    • May result in speed variation conflicts.
    • Boring experience.
Photo of a paved trail through woods.
Photo: NTEC Image Library.
Silver Comet Trail, Georgia.

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Shared Use Paths: Width

  • How much use will there be?
  • 8 foot minimum for low-use facilities:
    • Connectors between cul-de-sac neighborhoods.
    • To avoid inviting cut-through motor vehicles.
  • Prefer 10 foot minimum, recommend 12 foot, more if needed.
  • Avoid designing only for the minimum.
Photo of Peter Axelson in his wheelchair along a trail marked with sign detailing trail accessibility.
Photo: Peter Axelson, Beneficial Designs.
Contractor for FHWA's Designing Sidewalks and Trails for Access,
Best Practices Design Guide.

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Shared Use Paths: Width

  • High use facilities: Consider separating "heels and wheels" on two separate paths.
Photo of people on a trail with two adjacent or parallel paved treadways. Photo of a trail with two adjacent or parallel treadways; one paved another dirt track intended for equestrians.
Left photo: Pinellas County Rail-Trail, Florida. Stuart Macdonald, American Trails.
Right photo: USDA Forest Service: Equestrian Design Guidebook for Trails, Trailheads, and Campgrounds.

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Shared Use Paths: Width

Passing Space

  • Accessibility requirement: At least 60 inches (1525 mm) width within 1,000 foot (300 m) intervals.
  • Usually not an issue for Shared Use Paths.
  • Avoid designing only for the minimum.

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Shared Use Paths: Slope

Slope: Accessibility is the primary consideration.

  • Based on Outdoor Developed Areas Guidelines.
  • Access Board to propose stricter guidelines:
    • Either Public Rights of Way (PROW), or
    • Outdoor Recreation Access Routes (ORAR).
  • At highway crossings: Highway slope is trail cross slope, highway cross slope is trail slope.
Photo of paved flat trail. Photo of curved and variably sloped backcountry trail.
Left photo: NTEC Image Library. Silver Comet Trail, Georgia.
Right photo: USDA Forest Service, Trail Construction and Maintenance Notebook.

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Shared Use Paths: Slope

Slope: <5% to the extent feasible.

Slope ORAR Trail
1:20 (5%) any length any length
1:12 (8.33%) up to 50 feet up to 200 feet
1:10 (10%) up to 30 feet up to 30 feet
1:8 (12.5%) no up to 10 feet

Trail: No more than 30% of the total trail length shall exceed 1:12 (8.33%).

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Shared Use Paths: Slope

Change of grade. Transitions should have minimum grade changes (less than 11%) for a gradual transition for wheelchair users.
  • Avoid abrupt grade changes:
    • Not only annoying, they can be dangerous.

Change of grade. Transitions should have minimum grade changes (less than 11%) for a gradual transition for wheelchair users.
From FHWA’s Designing Sidewalks and Trails for Access, Best Practices Design Guide
Left drawing: www.fhwa.dot.gov/environment/bicycle_pedestrian/publications/sidewalk2/sidewalks214.cfm#gra
Right drawings: www.fhwa.dot.gov/environment/bicycle_pedestrian/publications/sidewalk2/sidewalks207.cfm#cha

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Shared Use Paths: Rest Intervals

Rest Intervals: A place to stop and rest.

  • Where running slopes exceed 1:20 (5%), at intervals no greater than the lengths permitted under running slope.
  • Size: 60 inch (1525 mm) length, at least as wide as the widest trail segment adjacent to the rest area.
  • PROW Level Landing: 2%.
  • ORAR: 3% (5% if drainage needs).
  • Trail: 5% (exempt if not possible).
  • Rest area may be off to the side.

Frequent rest areas that include benches and wheelchair spaces provide relief from prevailing grades.
From FHWA's Designing Sidewalks and Trails for Access, Best Practices Design Guide
www.fhwa.dot.gov/environment/bicycle_pedestrian/publications/sidewalk2/sidewalks214.cfm#sha1

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Shared Use Paths: Cross Slope

Cross Slope: <2% on paved surfaces.

  PROW ORAR Trail
General: 2% 3% 5%, 3% preferred
Exception: 5%* 5%** 10%**

* At street crossings without stop control or at midblock.
** If needed for drainage on an unpaved surface.

Superelevation? Accessibility trumps.

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Shared Use Paths: Vertical Clearance

  • Accessibility: 80 inches minimum.
  • Equestrian Use: 10 feet minimum.
Graphics showing various scenarios where branches from a tree could encroach on the trail tread impacting trail users. Graphics showing various scenarios where branches from a tree could encroach on the trail tread impacting trail users.

Top left: USDA Forest Service: Equestrian Design Guidebook for Trails, Trailheads, and Campgrounds.
Top right: From FHWA's Designing Sidewalks and Trails for Access, Best Practices Design Guide
Bottom left: FHWA's Designing Sidewalks and Trails for Access, Best Practices Design Guide.
Bottom right: U.S. Department of Justice, Civil Rights Division, Disability Rights Section: ADA Checklist for Polling Places, page 18.

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Shared Use Paths: Vertical Clearance

  • Maintenance vehicles: 12 feet? More?
  • Provide warnings or barriers for low overhead clearance: detectable by people with visual impairments.
Photo Collage of Various scenarios where vertical clearance needs to be considered.

Stair photo: US Access Board archives.
Top stair drawing: U.S. Department of Justice, Civil Rights Division, Disability Rights Section: ADA Checklist for Polling Places, pages 17/31.
Bottom stair drawing: US Access Board, Americans with Disabilities Act and Architectural Barriers Act Accessibility Guidelines, July 23, 2004, Figure 307.4.
Right photo: Clear Creek Trail crossing under Burlington Northern Railroad embankment, Jefferson County, CO; photo by Stuart Macdonald, August 1, 2009.

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Updated: 02/10/2014
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