Bicycle provisions

With regard to bicycle treatments, the designer should strive to provide bicyclists the choice of proceeding through the roundabout as either a vehicle or a pedestrian. In general, bicyclists are better served by treating them as vehicles. However, the best design provides both options to allow cyclists of varying degrees of skill to choose their more comfortable method of navigating the roundabout.

To accommodate bicyclists traveling as vehicles, bike lanes should be terminated in advance of the roundabout to encourage cyclists to mix with vehicle traffic. Under this treatment, it is recommended that bike lanes end 30 m (100 ft) upstream of the yield line to allow for merging with vehicles (11). This method is most successful at smaller roundabouts with speeds below 30 km/h (20 mph), where bicycle speeds can more closely match vehicle speeds.

To accommodate bicyclists who prefer not to use the circulatory roadway, a widened sidewalk or a shared bicycle/pedestrian path may be provided physically separated from the circulatory roadway (not as a bike lane within the circulatory roadway). Ramps or other suitable connections can then be provided between this sidewalk or path and the bike lanes, shoulders, or road surface on the approaching and departing roadways. The designer should exercise care in locating and designing the bicycle ramps so that they are not misconstrued by pedestrians as an unmarked pedestrian crossing. Nor should the exits from the roadway onto a shared path allow cyclists to enter the shared path at excessive speeds. Exhibit 6-39 illustrates a possible design of this treatment. The reader is encouraged to refer to the AASHTO Guide for Development of Bicycle Facilities (12) for a more detailed discussion of the design requirements for bicycle and shared-use path design.