Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges
Alternative
Intersections and Interchanges (A.I.I.s)
are designs that improve operations and safety for motorized traffic by strategically
adjusting the geometric features at a given location, working on the general principle of redistributing
motor vehicle demand at an intersection in an attempt to limit the need to add
capacity with new lanes to improve traffic flow.
The TRB National Cooperative Highway Research Program's
NCHRP Research Report 948:
Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges
provides specific guidance for four common A.I.I.s: Diverging Diamond Interchange (DDI), Restricted
Crossing U-Turn (RCUT), Median U-Turn (MUT), and Displaced Left-Turn (DLT).
These designs may involve reversing traffic
lanes from their traditional directions, which may introduce confusion and create safety issues
for pedestrians and bicyclists. In addition, pedestrian paths and bicycle facilities may cross
through islands or take different routes than expected. These new designs are likely to require
additional information for drivers, bicyclists, and pedestrians as well as better accommodations
for pedestrians and bicyclists, including pedestrians with disabilities.
This Summary Last Modified On: 2/2/2021