Roundabouts can present a number of risks for motorcyclists since accelerating, braking and maneuvering are all necessary. As highlighted earlier within the chapter, this can be compounded when there are large amounts of pavement markings and metal plates in the pavement which can introduce variations in skidding resistance.

Collisions at roundabouts typically involve:

Drivers failing to yield;
Drivers looking but failing to see a motorcyclist;
Misjudgment of motorcyclist’s speed; and
Tight curves on entry.

Treatment: Motorcycle collisions at roundabouts can be partly mitigated by clear signing and markings, by limiting visibility to the left until 50-ft before the entry using suitable screening ( ), and by ensuring that the lane assignments of a multilane roundabout are self-explanatory.

Designers should avoid sharp curves on roundabout approaches and entries as these can cause loss of control collisions for motorcyclists. Reverse curves intended to calm traffic should be designed to keep side forces minimal. Tangent sections between consecutive horizontal curves of 75-ft or greater length are recommended to allow a motorcyclist to regain balance before navigating the second horizontal curve. Designers should also ensure that surfacing materials and pavement markings have suitable skidding resistance, especially at the crosswalks and yield entry lines where YIELD words, yield symbols, and dashed lines will be present to delineate the yield point at a roundabout entry.