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Designing for Nonmotorists

Recreation: Where Engineering and Art Meet

Presented at the FHWA Design Discipline Seminar
June 25, 2014
Leesburg VA

(Download Powerpoint Version / 4 MB)

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

Photo: Transportation Alternatives Data Exchange (TrADE).

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

Presented by:
Christopher Douwes, Community Planner

Transportation Alternatives Program
Recreational Trails Program
Federal Highway Administration

Photo of Christopher Douwes giving a Powerpoint presentation.

Photo of Christopher Douwes, Community Planner, FHWA, presenting at FHWA Civil Rights Discipline Training, June 23, 2009, Albuquerque NM. Photo: Henry Droughter, Equal Opportunity Specialist, FHWA Pennsylvania Division


Recreational Trails

  • Why does FHWA care?
  • Eligible for Recreational Trails Program funds.
  • May be eligible for Federal Lands Highway funds.

Photo collage of trails.

Photos from the Recreational Trails Program website.
Left: Mountain bike trails at Butte State Park, Montana.
Top right: ATV trail on the Bull Run Guest Ranch near Cascade, Montana.
Bottom right: Snowmobiles at Eagle River, Wisconsin.

Recreational Trails

What is the trail purpose?

  • What are the skill levels?
    • Beginners?
    • Family outings?
    • Technical skills?
    • Challenge course?
    • Freeriding? Speed?
  • I-5 Colonnade, Seattle

Recreational Trails
What do you design for?

Accessibility: See

  • Federal agencies and Federal lands: see Final Accessibility Guidelines for Outdoor Developed Areas.
  • State, local, and private, including Federal-aid: see Regulatory Negotiation Committee on Accessibility Guidelines for Outdoor Developed Areas Final Report.
  • States may choose one or the other, or choose the "more accessible" of the two options.
  • Access Board is still considering ADA guidelines.
  • In general: An accessible trail is a sustainable trail.

Access Board website:

Recreational Trails: Surface

Surface: Firm and stable for accessibility.

  • Must accommodate wheelchairs to be accessible.

But not all recreational trails will be accessible.

  • Mountain bike trails:
  • Equestrian trails
  • Motorized trails
  • Remote hiking

Mountain bike trail features made of stone.

Photos: From International Mountain Bicycling Association.
Publication developed with funding in part through FHWA's Recreational Trails Program.

Recreational Trails: Surface

Surface: Likely not paved.

  • Consider accessibility guidelines for trails.
  • Engineered or natural surface?

Tread Obstacles may exist:

  • Roots, rocks, ruts, bumps, etc. Keep <2 inches.
  • Drainage features. May affect cross slope.

Gaps: Usually in bridges and boardwalks. Keep <0.5 inches, or <0.75 inches by exception.

Recreational Trails: Width

  • What will be the user experience?
  • Design for minimum impact.
  • Accessible trails: generally 36 inch minimum, with exceptions if necessary.
  • Mountain bikes: narrow preferred: 12-24 inches.
  • Motorcycles: narrow preferred: 18-24 inches.
  • Equestrians: consider equestrian widths.
  • ATVs: wide enough for an ATV, not more.
  • ROVs/UTVs: wider than ATVs.

ATVs: All-terrain vehicles
ROV: Recreational Off-road Vehicle
UTV: Utility Vehicle

Recreational Trails: Control Water!

  • Avoid the Fall Line:
    • Don't let water run down the trail!
  • An accessible trail usually is a sustainable trail.
  • General: <5% to the extent feasible, but...
  • Consider the "half rule":
    • Keep trail slope to less than half of the terrain slope.
    • Keep the running slope under 10% if feasible.
  • Rest intervals needed for accessible trails.

The "half rule" is not a "rule". It is a consideration, and might not work depending on soils, surrounding terrain, rainfall, expected use, etc.

Trail Slope: Grade Reversals

Grade reversals stop water flowing down the trail.

Photo of a trail / grade reversal.Graphic showing proper grade reversal design.

Trail Slope: Rolling Grade Dips

Easy way to get water off an existing trail.

Photo of a trail / grade dip. Graphic showing proper design of a grade dip.

Photo and Drawing from USDA Forest Service, Trail Construction and Maintenance Notebook.

Cross Slope: Control Water!

Graphic of a pair of legs standing on a trail representing safe cross slope.
  • Maintain sheet flow across the 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.

If your ankles start to roll, the tread has too much outslope.

Drawing from USDA Forest Service, Trail Construction and Maintenance Notebook.

Recreational Trails: Cross Slope

Graphics showing differences between bench cuts.

Prefer a "full bench cut" over a "half bench" cut.

  • Full bench
    • Holds its shape.
  • Half bench
    • Easier to construct.
    • But it slumps over time.

Drawings from USDA Forest Service, Trail Construction and Maintenance Notebook.

Trail Cross Slope: Sheet Flow

Sheet Flow Example

Graphic showing runoff accross a trail.

Drawing from USDA Forest Service, Trail Construction and Maintenance Notebook.

Trail Cross Slope: Sheet Flow

  • Knicks constructed into existing trails will drain puddles from flat areas.
  • A semicircle cut into the tread, about 3 m (10 feet) long and outsloped the center.

Photo and graphic of trail design techniques.

Photo and Drawing from USDA Forest Service, Trail Construction and Maintenance Notebook.

Please Avoid!

Graphic of a water bar.
  • Don't add barriers to trails.
  • Waterbars: To get water off the trail.
    • Very popular. Not very effective.
    • Not accessible. Possibly dangerous.
    • Need ongoing maintenance.
    • If you think you need a waterbar, the trail is in the wrong location.
    • Grade reversals, rolling dips, and knicks function much better.
  • Avoid bollards (see Shared Use Path discussion).

Drawing from USDA Forest Service, Trail Construction and Maintenance Notebook.

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Updated: 07/22/2014
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