The newsletter of AMERICAN TRAILS -- NEW YEARS 1998

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Universal trail assessment process: how it works and why it's important

By Kathleen Wong, Beneficial Designs, Inc.

American Trails is honored to take on implementation of the Universal Trail Assessment Process (UTAP) which was developed by Beneficial Designs. This project meets our mission of creating trail systems for ALL Americans. The vision is to provide standardized, objective information about the availability and condition of existing trails to ALL trail users, both with and without disabilities. Information gained from trail assessment will also help us develop better trail planning and design guidelines.

At a 1990 National Council on Disability hearing in Jackson Hole, Wyoming, Peter Axelson heard others voice a problem he too often faced himself: existing information about trails didn't give people with disabilities enough information to tell whether a trail was accessible for them. A wheelchair user and outdoors enthusiast himself, he determined to find a way to provide visitors with this information.

As founder of Beneficial Designs, a firm that creates technologies to facilitate universal access, Axelson initiated a project to improve trail access without paving over the wilderness. With the National Park Service, the National Forest Service, and many volunteers, Beneficial Designs analyzed trails for access characteristics in Montana's Gallatin National Forest and Yellowstone National Park. Axelson says, "using simple surveying tools, we measured everything we could think of on and around the trail at regular intervals. From this information, we identified five characteristics that affected access: grade, trail width, cross slope, surface type, and obstacles."

Axelson realized that converting the raw information into classifications such as "moderate" or developing a rating to qualify for a blue handicapped sign wouldn't give visitors much more information than the existing "length, elevation" signs on most trails. Instead, he opted for a universal approach that would provide useful information for all trail users, regardless of their abilities.

A grant from the National Center for Medical Rehabilitation Research within the National Institute of Child Health and Human Development in the National Institutes of Health enabled research to continue. Beneficial Designs to developed a standardized process for measuring trails, using a team of three to four people, equipped with compasses, a digital inclinometer, tape measures, and clinometers. The data is then entered and processed by computer to provide trail data in a form that is useful to trail visitors, including trail length, elevation change, maximum and average cross slopes and grades, sites where there are obstacles or the surface type changes, and the minimum and average width of the trail. A system of information symbols and trail signage layouts were also developed to visually convey trail data in attractive, easy to read formats. Finally, audio descriptions of trail access information were developed for people with visual impairments.

Why do we need Universal Access Information?

The level of accessibility of a recreation trail can only be defined with respect to the functional abilities and needs of an individual. For example, a trail that is easy for an experienced hiker may be moderately difficult for a family with a child in a stroller and impossible for a manual wheelchair user with limited upper body strength. Examination of the needs of different users led to the identification of five key trail parameters: grade, cross slope, width, surface type and obstacles. Objective information about these five parameters will enable all users to determine the level of access and challenge offered by the trail, as well as if assistance will be required in order to successfully and safely reach the destination.

Trail Grade: The effects of grade have a greater impact on individuals that use assistive mobility devices in comparison to strong or even weak ambulators. For wheelchair users, ramp grades of 14%, 20% and 24% require approximately 70%, 130% and 180% more work, respectively, than a standard 8% grade (1:12) ramp. The amount of energy required by ambulators is proportionately less than that for wheelchair users. Research has shown that the level of difficulty perceived by persons negotiating different grades is significantly influenced by disability and assistive device used. Wheelchair users tend to rate the difficulty of grades higher in comparison to ambulatory individuals.

The grade of a trail is also critical in terms of the safety of the wheelchair user. Wheelchairs, both manual and powered, have a certain degree of static and dynamic stability which are dependent upon the wheelchair model and set-up. Everyday manual wheelchairs tested according to the ANSI/RESNA wheelchair standards are reportedly stable on grades up to 15.8 to 30.6% (9 to 17 deg., respectively), depending on the model. In addition, the ability of the wheelchair rider to compensate for changes in grade by leaning forward or back in the wheelchair influences how steep a grade the rider will be able to negotiate independently without tipping over backward or forward. Therefore, if a specific wheelchair rider knows that a standard 1:12 (8.3%) ramp into a building is at the limits of his/her abilities, he/she would be able to compare the average and maximum grade of a specific trail and determine if that trail will provide access to that particular wheelchair user.

Cross Slope: Similar to grade, cross slope also has a significant impact on the level of access of a trail to wheelchair users. In comparison to the amount of work required to propel a wheelchair across a 2% cross slope, 8% and 16% cross slopes require approximately 1.4 and 2 times the amount of work, respectively. In a research study wheelchair users tended to give higher ratings of difficulty than those who were ambulatory at cross slopes greater than 5%. Typically, the potential risk of tipping over sideways in a wheelchair is not as great as tipping over backward or forward. Thus, wheelchair users will use the average and maximum cross slope values to determine if they are capable of negotiating the cross slopes on the trail.

Width: Objective information about the width of the trail and the locations of the narrowest sections of the trail is critical for persons that use mobility devices such as strollers, walkers and wheelchairs. The average manual wheelchair has a wheelbase width of less than 28 inches. If a trail narrows to 26 inches, the 28 inch wheelchair rider knows that he/she will not be able to venture past this point unless he/she is capable of transferring out of the chair and maneuvering the chair through this narrow location. If the width of the trail is disclosed, mobility device users will be able to determine exactly how far they will be able to hike and if they will be able to reach the destination.

Surface Type: The type of trail surface has a great amount of influence on the degree of access for all user groups. Objective test methods and portable devices for the measurement of surface firmness and stability are currently under development. Surface firmness primarily affects the amount of energy required to ambulate or propel a wheelchair across the surface. Surface stability mainly influences the amount of energy required to maneuver or turn a wheelchair through the surface. In addition, for persons that use crutches or walkers, lack of surface stability would pose a potentially hazardous situation if the device moves while the person leans on the device for support during walking.

Using these draft test methods, several different surfaces were measured. In comparison to propelling a wheelchair up a standard 1:12 (8%) ramp, a trail with the same grade and a decomposed granite surface required 10.6% more work. The results also revealed that level trails with engineered wood fiber surfaces required an average of 25% less work than a standard 1:12 (8%) ramp. Testing on pea gravel was not successful, since the front casters imbedded into the surface making it impossible for the test to be performed, regardless of strength of the test subject propelling the wheelchair.

The development of standardized test methods and a portable device will enable objective measurements of surface firmness and stability to be made. Recreationists can use this information to help make informed decisions about which trails to hike.

Obstacles: Obstacles such as rocks, ruts and roots can pose a substantial barrier to wheelchair users and strollers, especially if they are found continuously throughout the entire length of the trail. Powered wheelchairs have a certain obstacle climbing ability which is dependent upon the model and type of front casters and often limited by the vertical clearance under the chair. Manual wheelchair riders are limited by their own physical strength and wheelchair maneuverability skills. Information about the types of obstacles found on the trail is also needed by persons pushing children in strollers, which typically have small wheels that can not roll easily over larger obstacles. Obstacles can also hinder access to trails by ambulators with poor balance or agility. Therefore, objective information about the type and magnitude of obstacles found on the trail is included in the Universal Access Information.

If you are interested in becoming a Universal Trail Assessment Process Partner, please contact Pam Gluck at (520) 632-1140; E-mail:

Benefits of Trail Assessment

The Universal Trail Assessment Process benefits all trail users and land management agencies in a variety of ways: