7.6.3 Unpaved Multi-Use Trails
In corridors of low trail user volumes , multi-use trails may be unpaved . Unpaved trails may not be safe for all users . While the construction cost may be lower , they tend to have a higher maintenance cost and shorter life-cycle . While bicycle speeds are lower , unpaved trails are not recommended for novice users , for multiple age groups or for motorized equipment ( Figure 7.63.1 ).
Design Criteria :
• A one-way unpaved facility is to be a minimum of 6 feet wide . The clearing and grubbing area is approximately 12 feet wide and the selective thinning area is approximately 20 feet ( Figure 7.63.2 ).
• A two-way unpaved facility is to be a minimum of 10 feet wide . The clearing and grubbing area is approximately 18 feet and the selective thinning area is 30 feet ( Figure 7.63.3 ).
• Selective thinning is meant to increase visibility along the trail or pathway corridor . Mature trees that do not create a visibility hazard should be maintained .
• The recommended pavement surface is crushed aggregate , sand , clay , wood chips , or stabilized earth .
• Provide a 3-foot-wide graded shoulder minimum on 6-foot-wide paths and 5-footwide graded shoulders on 10-foot-wide paths .
• Side slopes to be a maximum of 1:6 adjacent to both sides of trail . When the bottom of the slope is unsafe , dense shrubbery , chain link fence , or other physical barrier may be needed .
Figure 7.63.1 . Example of unpaved multi-use trail . Unpaved trails usually are gravel , mulch , or natural surface .
Figure 7.63.2 . One-way unpaved 6-foot multi-use trail .
Chapter 7 : Design Guidelines | 7-57