16.2.1 Surface:
Outdoor Developed Areas Accessibility Guidelines: Firm and stable
AASHTO Guide for the Development of Bicycle Facilities, 1999: Bicycles need the same firmness and stability as wheelchairs; skaters usually require a smooth, paved surface. Most shared use paths are paved, although crushed aggregate surfaces are used on some paths.
16.2.2, Clear Tread Width:
Outdoor Developed Areas Accessibility Guidelines: 36 inches (3 feet; 915 mm); exception for 32 inches (815 mm).
AASHTO Guide for the Development of Bicycle Facilities, 1999: Shared use paths usually require a minimum 3 meter (10 foot) width, plus a 0.6 meter (2 foot) safety buffers on both sides. A 2.4 m (8 ft) width may be allowed in low use facilities.
Posts or bollards installed to restrict motor vehicle traffic should be spaced 1.5 m (5 feet) apart. Posts or bollards should be brightly painted and reflectorized for visibility. When more than one post is used, use an odd number, with one on the centerline to help direct opposing traffic.
16.2.3, Surface Openings (Gaps):
Outdoor Developed Areas Accessibility Guidelines: To prevent wheelchair wheels and cane tips from being caught in surface openings or gaps, openings in trail surfaces shall be of a size which does not permit passage of a ½ inch (13 mm) diameter sphere, elongated openings must be perpendicular or diagonal to the direction of travel; exception to permit parallel direction elongated openings if openings do not permit passage of a ¼ inch (6 mm) sphere; second exception to permit openings which do not permit passage of a ¾ inch (19 mm) sphere. (1)
AASHTO Guide for the Development of Bicycle Facilities, 1999: The AASHTO Guide does not specify a maximum dimension for a surface opening, but openings should be minimized. Openings should not permit a bicycle wheel to enter. (2) Grates should be flush with the surface, and elongated openings should be perpendicular to the direction of travel. (Diagonal openings are more difficult for bicyclists to negotiate). Where openings are unavoidable, they should be clearly marked.
16.2.4, Protruding Objects
Outdoor Developed Areas Accessibility Guidelines: ADAAG 4.4; provide a warning if vertical clearance is less than 80 inches (2030 mm)
AASHTO Guide for the Development of Bicycle Facilities, 1999: Protruding objects should not exist within the clear tread width of a shared use path. Vertical clearance on shared use paths should be a minimum of 3 m (10 feet) or the full clear width and the safety buffers. Where vertical barriers and obstructions, such as abutments, piers, and other features are unavoidable, they should be clearly marked.
16.2.5, Tread Obstacles (Changes in level, roots, rocks, ruts)
Outdoor Developed Areas Accessibility Guidelines: Up to 2 inches (50 mm); exception up to 3 inches (75 mm).
AASHTO Guide for the Development of Bicycle Facilities, 1999: Tread obstacles are hazardous to bicyclists and skaters. The surface of a shared use path should be smooth and should not have tread obstacles.
16.2.6, Passing Space
Outdoor Developed Areas Accessibility Guidelines: At least 60 inches (1525 mm) width within 1,000 foot (300 m) intervals. Appendix note recommends more frequent intervals for some trail segments.
AASHTO Guide for the Development of Bicycle Facilities, 1999: Shared use paths should have a minimum clear width of 3 m (10 ft), exception for 2.4 m (8 ft).
16.2.7.1 Cross slope:
Outdoor Developed Areas Accessibility Guidelines: 1:20 (5%) maximum; exceptions for open drains up to 1:10 (10%).
AASHTO Guide for the Development of Bicycle Facilities, 1999: For drainage, shared use paths should have a minimum 2% (1:50) cross slope on a paved surface. On unpaved shared use paths, particular attention should be paid to drainage to avoid erosion. Curves on shared use paths may require super elevation beyond 2% (1:50) for safety reasons. The Guide suggests limited cross slope for accessibility reasons.
16.2.7.2 Running Slope:
Outdoor Developed Areas Accessibility Guidelines:
- 1:20 (5%) any length;
- 1:12 (8.33%) for up to 200 feet;
- 1:10 (10%) for up to 30 feet;
- 1:8 (12.5%) for up to 10 feet;
- No more than 30% of the total trail length shall exceed 1:12
AASHTO Guide for the Development of Bicycle Facilities, 1999: Running slopes on shared use paths should be kept to a minimum; grades greater than 5 percent are undesirable. Grades steeper than 3 percent may not be practical for shared use paths with crushed stone or other unpaved surfaces. Where terrain dictates, grade lengths are recommended as follows:
- < 5% (< 1:20) any length
- 5-6% (1:20-16.7) for up to 240 m (800 ft)
- 7% (1:14.3) for up to 120 m (400 ft)
- 8% (1:12.5) for up to 90 m (300 ft)
- 9% (1:11.1) for up to 60 m (200 ft)
- 10% (1:10) for up to 30 m (100 ft)
- 11+% (1:9.1) for up to 15 m (50 ft)
16.2.8, Resting Intervals
Outdoor Developed Areas Accessibility Guidelines: Size: 60 inch (1525 mm) length, at least as wide as the widest trail segment adjacent to the rest area. Less than 1:20 (5%) slope in any direction. Resting areas are required where trail running slopes exceed 1:20 (5%), at intervals no greater than the lengths permitted under running slope (see 16.2.7.2 above)
AASHTO Guide for the Development of Bicycle Facilities, 1999: The Guide does not address resting intervals.
16.2.9, Edge protection:
Outdoor Developed Areas Accessibility Guidelines: Where provided, 3 inch (75 mm) minimum height. Handrails are not required.
AASHTO Guide for the Development of Bicycle Facilities, 1999: The Guide does not address edge protection. Some kinds of edge protection may be hazardous to bicyclists and skaters. The Guide has minimum railing height recommendations when needed for safety reasons.
16.2.10, Signs:
Outdoor Developed Areas Accessibility Guidelines: Accessible trails require designation with a symbol of accessibility, and information on total length of the accessible segment.
No traffic control sign information.
AASHTO Guide for the Development of Bicycle Facilities, 1999: Guidance on signing and marking is provided in the Manual on Uniform Traffic Control Devices (MUTCD), incorporated by reference as a Federal regulation (23 CFR 655.601). A proposed amendment for Part 9 (Traffic Controls for Bicycle Facilities) was published in the Federal Register on June 24, 1999 (64 FR 33802-33806). A rulemaking is scheduled for March 2000 that will have an update for Part 4 (Signals), that will include provisions for pedestrian signals for people with disabilities.