642.4 Pedestrian Grade Separations
The potential need for pedestrians to move across multilane facilities with lengthy distances between signalized intersections must be considered during design. For instance, near schools, parks, hospitals, public buildings or shopping centers there may be high demand for pedestrians to cross a roadway between signalized intersections. A raised median, with curb cuts, is the preferred approach to provide a safer crossing for pedestrians. A pedestrian underpass or overpass may also be considered if it is economically feasible.
It is not practical to develop warrants governing the construction of pedestrian grade separation facilities. Each situation must be considered on its own merits. Such facilities are generally warranted only at locations where exceedingly heavy volumes of pedestrian traffic must cross a heavy vehicular flow. When the construction of a pedestrian grade separation is considered, an investigation will be made including studies of pedestrian crossing volumes, type of highway to be crossed, location of adjacent crossing facilities, the predominant type and age of persons who will use the facility and the cost of constructing the pedestrian grade separation. A pedestrian grade separation will only be constructed when the need for the safe movement of pedestrians cannot be provided in a simpler cost efficient manner. Experience indicates pedestrians frequently underutilize these facilities. Where the facility offers a more convenient path than a crossing at street grade, the likelihood of general use by pedestrians is good. If the situation requires descending to a different level and then ascending to the original level, or ascending to a different level and then returning to the original level, the chance of general use is not good unless barriers are erected to force pedestrians to use the facility. Additional guidance concerning pedestrian grade separations can be found in an AASHTO publication Guide Specifications for Design of Pedestrian Bridges.