FREE books on trail maintenance and construction
Equestrian Design Guide Book for Trails, Trailheads and Campgrounds
available at http://www.fhwa.dot.gov/environment/rectrails/trailpub.htm

Geosynthetics for Trails in Wet Areas: 2008 Edition available at
http://www.fhwa.dot.gov/environmental/rectrails/trailpub.htm