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Surfaces for accessible trails

Construction tips and definitions of accessible surfaces for trails from the USFS Accessibility Guidebook on Outdoor Recreation and Trails.
From the New Years 2007 American Trails Magazine

By Janet Zeller

The surface of an Outdoor Recreation Accessibility Route and the surface surrounding constructed features must be firm and stable. No exceptions are allowed. Slip resistance is not required because leaves and needles, dirt, ice, snow, and other surface debris and weather conditions are components of the natural environment that would be difficult, if not impossible, to avoid.

Paving the Wilderness?

Does a firm and stable surface always mean concrete and asphalt? No! The surface provision states that the type of surface material used should be appropriate to the setting and level of development. Some natural soils can be compacted so they are firm and stable. Other soils can be treated with stabilizers without drastically changing their appearance.

Many surfaces that appear natural and that meet the firm and stable requirements also are available on the market. Designers are encouraged to investigate these options and use surfacing materials that are consistent with the site's level of development and that require as little maintenance as possible.

What is Firm and Stable?

What sort of surface is firm and stable? In general, if the answer to both of the following questions is yes, the surface is probably firm and stable:

  • Could a person ride a narrow-tired bicycle across the surface easily without making ruts?

  • Could a folding stroller with small, narrow plastic wheels containing a three-year-old be pushed easily across the surface without making ruts?

Firm and stable surfaces prevent assistive devices from sinking into the surface, which would make movement difficult for a person using crutches, a cane, a wheelchair, or other assistive device. In the accessibility guidelines, the standard assistive device is the wheelchair because its dimensions, multiple moving surface contact points, and four wheels often are difficult to accommodate. If a person using a wheelchair can use an area, most other people also can use that area.

Construction Tips on Surfacing Materials

Generally, the following materials provide firmer surfaces that are more stable:

  • Crushed rock (rather than uncrushed gravel)

  • Rock with broken faces (rather than rounded rocks)

  • A rock mixture containing a full spectrum of sieve sizes (rather than a single size)

  • Hard rock (rather than soft rock that breaks down easily)

  • Rock that passes through a 12-inch (13-millimeter) screen

  • Rock material that has been compacted into 3- to 4-inch (75- to 100-millimeter) thick layers (not thicker layers)

  • Material that is moist, but not too wet, before it is compacted (rather than material that is compacted when it is dry)

  • Material that is compacted with a vibrating plate compactor, roller, or by hand tamping (rather than material that is laid loose and compacted by use)

The Forest Service Accessibility Guidebook on Outdoor Recreation and Trails will help users integrate accessibility into planning, design, construction, and maintenance of outdoor recreation facilities and trails while maintaining the natural setting. It provides detailed information about accessibility requirements in an easy-to-use format, with photos, illustrations, and design tips, hotlinks, and sidebars. This guidebook will also help Forest Service personnel, partners, contractors, and Federal and State agencies working in cooperation with the Forest Service understand how to apply the Forest Service Outdoor Recreation Accessibility Guidelines and Forest Service Trail Accessibility Guidelines.

See for more information on Accessible Trails, including links to the new Forest Service Accessibility Guidebook and many other articles and resources.

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