More References

Publications

NCHRP Research Report 1043. Guide for Roundabouts 

Roundabout implementation in the United States has increased in the last decade, and practitioners have learned lessons in successfully applying roundabouts in various land use and transportation environments and contexts.The TRB National Cooperative Highway Research Program's NCHRP Research Report 1043: Guide for Roundabouts provides information and guidance on all aspects of roundabouts.Supplemental to the report is NCHRP Web-Only Document 347: Background and Summary of a Guide for Roundabouts, which describes the research for and development of the guide.DOI: 10.17226/27069.

NCHRP Synthesis 488. Roundabout Practices 

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 488: Roundabout Practices summarizes roundabout policies, guidance, and practices within state departments of transportation (DOTs) as of 2015. The synthesis may be used as a reference for state agencies that are creating or updating their roundabout and intersection control policies. DOI: 10.17226/23477 

NCHRP Research Report 948. 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. DOI: 10.17226/26072