Guest Blog: Trail Surfaces by Camille Lore
When I attended a week long Department of the Interior Trail Construction and Management class, I learned that even the most rocky, rugged and steep section of the Appalachian Trail at Harper's Ferry could have been built to accommodate users with mobility challenges. Trail construction and planning has certainly changed since the 1960s.
A well planned trail demands forethought and careful site evaluation. Today, the Appalachian Trail in West Virginia has obvious erosion and is not accessible to those who have mobility challenges. Of course, when the trail was planned and laid in the early 1900s, there was no National Environmental Policy Act or permits for that matter. There were no bobcats or mini-skids building the trail.
Today, trail layout and design needs to take a holistic approach to the site and its users.
Initially, the trail planners need to consider:
· Who will be using the trail?
· What land features exist?
· What soil types are present?
· What sensitive environmental features are on site?
· When will the trail get most use?
All, trails constructed today should be designed so they are accessible to users who have mobility challenges. With the specifications laid out in publications like the US Forest Service Trail Accessibility Guidelines, a plethora of engineers and landscape architects, there is no reason for any trail to exclude those who are mobility challenged. In the same vein, please don't think that users using mobility devices or child carriers want a perfectly smooth, pristine, boring trail either.
The US Forest Service's standards direct that improved trail surfaces must be “firm and stable” to be considered accessible.
“Firm” is defined as “not noticeably distorted or compressed by the passage of a device that simulates a trail user in a wheelchair. Surface firmness should be determined and documented during the planning process for the seasons for which a trail is managed, under normally occurring weather conditions.”
“Stable” is defined as “not permanently affected by normally occurring weather conditions and able to sustain normal wear and tear caused by the uses for which a trail is managed, between planned maintenance cycles.” Their guidance continues to say that many materials including crushed stone, fines, packed soil and other natural materials can be used to provide a suitable surface for trails.
What is the setting of the trail? Will the trail be over a wetland or forested area? Is the setting more developed or less formal? What is the capacity of the group providing management and maintenance of the trail?
If the proposed trail is going in a small central park with simple vegetation and will only receive light use, is a 4 foot wide asphalt path really the right choice? Is there a budget and staff ready to repair cracks and replace degraded sections of trail, or would something like a crushed limestone path that only needs to be rolled out once a year be more appropriate? In terms of stormwater runoff coefficients, the two are nearly identical if there is no thought given to path shading and management of the velocity and quality of the runoff from the paths. If managed with recessed planting beds, either choice could be managed to provide improved stormwater quality.
Is grass a trail surface?
Grass is approximately 11% pervious. 11% may be less than you thought. However, grass will slow runoff and provide some mechanical filtration of particulates in stormwater. Concrete will not provide the same benefit and will also lead to heated stormwater runoff. Placed in the appropriate areas, grass certainly will adhere to the Forest Service's qualifications of “firm and stable” while providing additional benefits.
Porous paving is working!
The myth that porous paving only works in areas where it is 70 degrees year round and salt isn't needed on sidewalks is just outdated information! Porous paving is (and has been) working in the Philadelphia area for over 20 years. If a municipality is insistent on hard asphalt paths, would it be appropriate to use porous paving and underground infiltration? You bet.
Take a look at this demonstration of porous paving in action:
There are many options for trail surfaces. As long as they can adhere to the requirement of “firm and stable”, they can take many pleasing shapes and appearances-mulch, porous blocks, crushed stone, packed soil. The old idea of plopping down a plain asphalt path is not only outdated, but also demands more resources in the way of dollars and staff time than some of the more natural, less obtrusive materials. In the age of MS4 permits and requirements to clean up stormwater, more thought should go into trail surfaces than we gave them 20 years ago.
-Camille Lore has worked in municipal government and land use planning for the past 10 years. She is currently a grant writer for MadCityGrants (www.MadCityGrants.com), providing affordable, effective grantwriting for nonprofits in Pennsylvania, Virginia and Wisconsin.