Bicycles

Roundabouts may not provide safety benefits to bicyclists (1). Nevertheless, the recommended roundabout designs discourage erratic or undesirable driver behavior. They slow drivers to speeds more compatible with bicycle speeds, while reducing high-speed conflicts and simplifying turn movements for bicyclists. Typical commuter bicyclist speeds are around 25 km/h (15 mph), so entering a roundabout designed for circulating traffic to flow at similar speeds should be safer compared with larger and faster roundabout designs. Bicyclists require particular attention in two-lane roundabout design, especially in areas with moderate to heavy bicycle traffic.

As with pedestrians, one of the difficulties in accommodating bicyclists is their wide range of skills and comfort levels in mixed traffic. On single-lane roundabouts, bicyclists have the option of either mixing with traffic or using the roundabout like a pedestrian. The former option will likely be reasonably comfortable for experienced cyclists; however, less-experienced cyclists (including children) may have difficulty and discomfort mixing with vehicles and are more safely accommodated as pedestrians.

The complexity of vehicle interactions within a roundabout leaves a cyclist vulnerable, and for this reason, bike lanes within the circulatory roadway should never be used. On double-lane roundabouts, a bicycle path separate and distinct from the circulatory roadway is preferable, such as a shared bicycle-pedestrian path of sufficient width and appropriately marked to accommodate both types of users around the perimeter of the roundabout. While this will likely be more comfortable for the casual cyclist, the experienced commuter cyclist will be significantly slowed down by having to cross as a pedestrian at each approach crossing and may choose to continue to traverse a double-lane roundabout as a vehicle. It may sometimes be possible to provide cyclists with an alternative route along another street or path that avoids the roundabout, which should be considered as part of overall network planning. The provision of alternative routes should not be used to justify compromising the safety of bicycle traffic through the roundabout because experienced cyclists and those with immediately adjacent destinations will use it.