Since an off-road path lures users by the opportunity to bicycle away from traffic or through scenic settings, or to connect with destinations unavailable on the road network, it is important to minimize the number of roadway crossings or other intersections, both for safety reasons and to minimize delays and enhance patrons’ enjoyment. Where paths must cross roadways, driveways, or other paths, it is important that the trail design facilitates the safest and most convenient crossing movements possible. Where there is a conflict between safety and convenience, safety should take precedence. Trail intersections with roadways offer special design challenges, especially since trail users may have a wide range of cycling skills and diverse characteristics. The AASHTO Guide for the Development of Bicycle Facilities provides design guidelines for midblock, adjacent path and complex intersection trail crossings where the path crosses a roadway at an existing intersection or driveway.1 Signs and signals for the roadway and path, end of path transitions, markings, sight and stopping distance, ramp widths, and other intersection design issues are discussed, but each situation requires judgment on the part of the designer.
Both path-to-path and path-to-roadway intersections require careful planning and construction to maximize safety. Where crossings must occur, priority right-of-way should be established based on the type of intersecting travel-way, traffic volumes, speed, and other factors. Path users should be counted in the volumes, and where paths cross low-volume roadways or driveways and path use is high, priority should be given to the path. Warning and regulatory signs, traffic signals, and pavement treatments or markings should be used to clearly delineate which corridor has the right-of-way, coordinate interactions, and guide path users to safe crossing locations. A traffic control device (sign or signal) should be installed at all path-roadway intersections. Efforts should be made to minimize crossing delays to path users as some may be unwilling to tolerate significant delays.
Pathways must link to the street network and access points should be clearly marked and signed. Curb cuts should be flared to allow bicyclists to make safe turns onto or to exit the trail. On unpaved paths, a paved apron should extend at least 3 m (10 ft) from the edge of paved roadways. To prevent motorized traffic from inadvertently or intentionally accessing the trail, signs clearly noting that motorized traffic is prohibited, as well as brightly painted bollards or medians, should be installed in the center of a 3 m (10 ft) wide or less path, or no less than 1.5 m (5 ft) apart on a wider path. Access for maintenance and emergency vehicles must be provided.
Railroad corridors are often desirable locations for paths because they
generally have few roadway crossings and built-in off-grade crossings (overpasses
and underpasses) of roadways, streams, and other barriers where crossings
do occur. At railroad crossings, active devices such as bells and flashing
lights, or automatic gates triggered by the approach of a train may be
new construction, the cost of off-grade crossings may be considered prohibitive
but may be the best alternative where a trail needs to cross a busy or
high-speed corridor or if trail use is expected to be high. Some communities
such as Boulder, CO (see case
study #35), have used off-grade crossings
extensively for bike and pedestrian corridors. For safe and effective overpasses
and underpasses, adequate lighting is important for travel and for personal
safety. (See Tunnels/Underpasses
When trails must cross roadways at grade, it may be desirable to design the crossing at an existing intersection to minimize incidences of wrong-way riding along the roadway to the trail access. The crossing distance should be minimized. If the trail crosses a busy, multi-lane or high-speed road, a refuge island is a treatment that enables trail users to cross one leg of the roadway at a time. The crossing may be angled so that trail users turn toward oncoming traffic to cross the second direction of travel lanes. Lighting can also enhance the safety of path intersections with roadways, railways, and other paths, especially if extensive nighttime use is expected (such as in a busy urban area or near a college or university campus).
Intersection costs are part of the overall cost of the trail. Some treatments may be incorporated into roadway or intersection upgrades.