BACKGROUND

Innovative intersections and interchanges are junctions of two or more roads that do not use traditional intersection or interchange layouts. Examples include diverging diamonds, restricted crossing U-turns, displaced left turns, and roundabouts. Most innovative intersections/interchanges installed in the United States have roadway lighting, in part because lighting is supported by Federal Highway Administration’s (FHWA’s) Alternative Intersection and Interchange Report, and NCHRP Report 672: Roundabouts: An Informational Guide, second edition. Lighting, however, adds significantly to construction and maintenance costs, which can be a barrier to constructing roundabouts and other innovative intersections/interchanges. Research is needed to help practitioners determine what factors, in addition to safety, should be considered when designing lighting at these locations, such as social, environmental, economic impacts, maintenance, constructability, community concerns, and light pollution.  

OBJECTIVE

The objective of this project is to develop a practitioners’ guide for lighting at innovative intersections/interchanges, including roundabouts that (1) documents quantitative safety benefits associated with lighting for motorists and vulnerable road users (e.g., motorcyclists, pedestrians, bicyclists) at innovative intersections/interchanges; (2) establishes evidence-based criteria for determining whether or not to install lighting; and (3) identifies best practices, noteworthy considerations, and emerging approaches for lighting design at innovative intersections/interchanges, including roundabouts.