Designing low-maintenance trails
June 9, 2014
When I started designing non-motorized trails in the Holland area about 16 years ago, trail development was still in its infancy. Since then, I have designed or managed construction of about 150 miles of trails. As your community’s trail system develops, maintenance becomes a real concern. Here are 13 of my favorite maintenance-minimizing trail design tips:
- For a paved trail, use two courses of asphalt. The second course minimizes cracking and provides a much smoother surface for minimal extra up front cost. Contractors may ask if they can pave the same thickness in one course, because it saves them a little money. Do NOT allow it!
- Extend your gravel sub-base at least one foot beyond the paved trail edge. Any less and the edges can crack and eventually fail.
- Test the gravel gradation and compaction during construction. The wrong mix or sloppy compaction will cause early cracks in the pavement.
- If it is necessary to clear vegetation to build your trail, be careful to remove all roots – especially willow trees and yucca plants. They will grow back right through the pavement!
- Remove all dead and dying trees within 10 feet each side of the trail. Falling branches can be dangerous and the debris clutters trails.
- Keep your trail away from trees if possible. Roots and debris are two of a trail’s most common maintenance headaches.
If you cannot dodge trees and you are worried about roots wrecking the trail surface, consider installing a product similar to bio-barrier. Products like this do not injure the trees, but when installed correctly, they prevent the roots from growing under the trail.
- If your trail parallels a road, as often as possible, maintain a grass strip between the pavement edges. This protects both the trail and the road shoulder. It also minimizes road gravel washing all over your trail after it rains.
Layout and Structure
- If fill to build your trail, make sure the downhill side-slope is no steeper than 1 ft. of rise over 3 ft. width. If it is too steep, the slope often settles and takes the pavement edge with it.
- If your trail includes a bridge or boardwalks, include concrete approach ramps. This minimizes the inevitable settlement and “bump” at the transition point.
- If your trail goes downhill for longer than 300 ft., find a way to drain water off the trail surface into a swale, ditch, gutter or catch basin. Otherwise, the edge of the path, shoulders or the grass along the trail could wash out.
- If you are building a trail above native clay soil, consider placing a filter fabric between the clay and the sand/aggregate sub-grade. It will help produce a uniform stress on the clay and prevent uneven settlement and pavement cracks.
- In wet areas, make sure drainage goes under the trail, not over it. Build the trail higher if necessary. Use a culvert to convey flow or equalize ponding on both sides of the trail. Otherwise the trail becomes frequently wet and potentially dangerously slippery.
Scott Post is a board member at the West Michigan Trails and Greenways Coalition. He has designed nearly 150 miles of non-motorized trails in Michigan.