Welcome to the National Center on Accessibility.  This is our logo.  It consists of a white background, with green lettering that reads Recreation, Parks, and Tourism.  Choose this image link if you would like to skip the navigation links and go directly to the page content.

Learn about the National Center on Accessibility, including the services we provide, our mission, our partners, our staff, as well as our contact information.Learn about upcoming NCA training as well as how to obtain training tailored to your organization.Read NCA research articles, learn about NCA research projects, and volunteer to participate in a NCA research project.Learn about NCA technical assistance.Read NCA's many Publications and Videos, including Access Today, Making the Grade, and NCA news.Familiarize yourself with a wide variety of accessible products.

Font Size: This is the icon for the smallest font setting. | This is the icon for the medium font setting. | This is the icon for the large font setting. | This is the icon for the extra-large font setting.
NCA Home | Site Map | Contact Us
 Technical Assistance
Best Practices
Boating & Fishing
Cultural Arts
Fitness Centers
General Accessibility
 Making the Grade
NCA Monographs
NCPAD Monographs
Outdoor Developed Areas
Recreation & Leisure
Swimming Pools
Status of Rulemaking Research Publications Online Resources Products
  Trail Research: A Longitudinal Trail Research Program on Soil Stabilizers

This study was originally conducted by the National Center on Accessibility at Bradford Woods between 1997 and 1999.

The purpose of this project is to compare the effectiveness of surface treatments for creating a trail accessible to people with mobility impairments. Specifically, this study is examining the longitudinal effects of surface treatments on surface firmness and stability, the costs of applying the treatments, and their relative maintenance demands.

What is being tested:

    The trail base contains compacted soil indigenous to central Indiana. The types of surfaces used were Quarter Minus Limestone, #11 limestone (refers to stone size), and indigenous soil. Quarter Minus Limestone is a by-product of crushed limestone in which the limestone fines are no larger than a quarter inch and most fines are dust particles.

A Longitudinal Trail Research Program on Soil Stabilizers

All surface materials were applied in 3-inch depths. The stabilization products used with the surfaces were Mountain Grout*, Road Oyl Resin Modified Emulsion, and Stabilizer. Mountain Grout* is a single component hybrid polyurethane system designed to stabilize and solidify soils. (*Mountain Grout has since been changed and renamed). Stabilizer is a concentrated organic (ground seed hulls) soil additive powder. Road Oyl Resin Modified Emulsion is a pine resin emulsion and is not petroleum based.

Test Procedures:

  • To evaluate the surface, a device called a Rotational Penetrometer that measures the firmness and stability was used. This tool evaluates the surface by measuring how deep an eight inch pneumonic wheel that has a constant pressure of forty pounds will penetrate the surface when rotated 90 degrees.
  • Each one of the test plots is evaluated on a monthly basis, with readings being taken in random locations on each evaluation. Five different measurements are taken of each surface every month.
  • The same location is never measured twice in one month.
  • The test surface has received a large amount of foot traffic over the last two years. The plots are on the main path at Bradford Woods that connects the dining facility to the rest of the camp. This trail has an average of seventy-five users per day.
  • The test surfaces of the trail were lined with 2" x 6" boards to designate the sides of the trail and separate each surface application plot.
Note: The Rotational Penetrometer is used as a standard measurement device in the ANSI/RESNA Standard for Ground and Floor Surfaces

After Two Years of Use:

    1. Quarter Minus Limestone with Stabilizer
    This test plot has shown considerable wear and is breaking down at the sides. The results of this test so far have indicated that this surface has had an average of .36 -.59 inch penetrations.

    2. Quarter Minus Limestone with Road Oyl Resin Modified Emulsion
    This plot has shown little wear and is holding up well under all the trail use. There is an average penetration of .05 -.08 inches on this surface. This surface has proven to be very usable by people with mobility impairments.

    3. Quarter Minus Limestone with Mountain Grout Soil Stabilizer
    This plot has shown the least wear of all test plots, the average penetration on this plot was .009 -.03 inches.

    4. Quarter Minus Limestone
    This test plot has had an average penetration of .10 - .90 inches. This plot has shown instability when wet and under adverse temperature changes. This surface has degraded and broken down much faster than other surfaces where stabilizers have been applied.

    5. 50% #11 Limestone and 50% soil
    This surface has an average penetration of .45 - 1.2 inches, it has been the second worst surface in terms of decay.

    6. Soil
    This surface has had the poorest results over the last two years; the average penetration is .35 -1.80 inches. When wet, people with mobility impairments have deemed this surface inaccessible and the surface has shown a substantial amount of decay.

    7. Soil and Mountain Grout
    This surface has an average penetration of .21 - .87 inches with signs of decay on the edges of this test plot and in the middle.



Quarter Minus Limestone with Mountain Grout Soil Stabilizer .009-.03 inches
Quarter Minus Limestone with Road Oyl Resin Modified Emulsion .05-.08 inches
Quarter Minus Limestone .10-.90 inches
Soil and Mountain Grout Soil Stabilizer .21-.87 inches
Quarter Minus Limestone with Stabilizer .36-.59 inches
50% #11 Limestone and 50% soil .45-1.2 inches
Soil .35-1.80 inches


ANSI/RESNA Standards for Firmness and Stability

Very Firm/Stable Moderately Firm/Stable Not Firm/Stable
Firmness 0.3 inch or less >0.3 & <0.5 inch >0.5 inch
Stability 0.5 inch or less >0.5 & <1.0 inch >1.0 inch

Back to top

About NCA | Training & Education | Research | Technical Assistance | Publications & Videos | Products
Yellow Bar
National Center on Accessibility
501 North Morton Street - Suite 109
Bloomington, IN 47404-3732
Voice: (812) 856-4422
TTY: (812) 856-4421
Fax: (812) 856-4480
Comments: nca@indiana.edu
2001-03, The Trustees of Indiana University