Accessible Trail Guidelines: you may be more prepared than you think!
Comparing proposed Accessibility Guidelines with current recommendations for sustainable trail design.
By Mike Passo, Member, Board of Directors of American Trails
Imagine, if you will... the federal government has passed a new set of guidelines, however, you are in the position that you needn't do anything differently than you currently do because your current practices meet nearly all of the requirements of the new guidelines. In your dreams, right? Maybe not!
If you have been designing, building and maintaining your trails according to the principles of Sustainable Trail Design, then your trails by and large will comply with the Proposed Accessibility Guidelines for recreation trails that are currently being considered for adoption by the United States Access Board.
Recently, the proposed accessibility guidelines for trails have taken a big step towards adoption by all of the Federal Land Management agencies. The proposed guidelines have worked their way through the Office of Management and Budget (a process that has taken over 7 years to complete). The proposed guidelines will soon be put out for public comment for a period of 90-120 days.
The great thing about these proposed guidelines is that they very nearly match current sustainable trail design recommendations. Let's compare and contrast sustainable trail design with accessible trail design:
Sustainable design criteria suggest that a trail should rarely exceed 10% in grade. Trails over 10% inherently have problems with water management. Water tends to want to travel down the trail instead of sheet flowing across the trail. This leads to washout erosion on the trail tread causing increased trail tread maintenance and decreased long-term sustainability.
The current proposed accessibility guidelines require grades of 5% for any distance, 8.33% for up to 200 ft, 10% for 30 ft, 12% for 10 ft, and 14% for 5 ft when required in the bottom of a drainage structure.
Sustainable design criteria suggest a surface that is firm and stable in order to accommodate usage without degrading the tread surface. Proposed accessibility guidelines require a firm and stable surface.
Sustainable design criteria suggest a prepared tread surface of 32 inches in width. The beaten path may be narrower, however, the prepared tread width should be at least 32 inches wide to allow for traffic that inevitably tends to push the edges of the beaten path due to passing trail users, group trail use and inadvertent use of the fringes of the trail. Proposed accessibility guidelines require 36 inches with exceptions to 32 inches in width.
Take note that the only significant discrepancy between Sustainable and Accessible design occurs in the area of cross slope. Sustainable Design criteria suggests a minimum of 5% cross slope on the trail tread in order to ensure sheet flow of water across the trail. Cross slopes of less than 5% allow water to stay on the tread surface, which allows water to pick up velocity when grade increases.
This leads to washout erosion on the trail tread causing increased trail tread maintenance and decreased long-term sustainability. Proposed accessibility guidelines require a maximum of 5% cross slope, with an exception of up to 10% when required in the bottoms of drainage structures.
Grade Reversals and Curvilinear Alignment:
Sustainable Design criteria suggest trails should contain frequent grade reversals and follow a curvilinear alignment. In other words, the trail should have "ups and downs" and curve around trees, rocks, etc. This design creates an interesting trail for trail users and provides excellent opportunities to manage water on the trail tread. These design elements keep steeper sections of trail restricted to short distances and provide ample opportunities for resting intervals between each up and down, which are key elements of the proposed accessibility guidelines. Most folks would agree (whether you have a disability or not) that a trail with "ups and downs" is much better than a long, consistent uphill (or downhill) slog.
Any trails or portions of trails that can not be built to Sustainability/Accessibility recommendations, should then be signed in order to allow trail users to choose for themselves whether the trail meets their individual accessibility needs.
So, continue to build and maintain your trails according to current sustainability recommendations. You are building your trails right, and will continue to build your trails right, even after the adoption of Accessibility Guidelines for Recreation Trails.
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Updated August 21, 2015