The paper describes the circumstances supporting the final decisions for design and construction of a roundabout on Broad Street in Nashua, New Hampshire. It also describes operational conditions that have been recorded since completion of the roundabout. The paper describes the circumstances supporting the final decisions for design and construction of a roundabout on Broad Street in Nashua, New Hampshire. It also describes operational conditions that have been recorded since completion of the roundabout.

What is a modern roundabout?

The Broad Street intersection is by definition a "Modern Roundabout". The main characteristic of a modern roundabout is the "yield-at-entry" rule, meaning that traffic entering the roundabout must yield to traffic within. Other characteristics include deflection of the vehicle by use of a circular center island, and splitter islands on each approach. The splitter islands control entry speed and deter illegal left turns. They also serve as refuge islands for pedestrians.

Further Reading:

Broad Street Roundabout - Position Paper