Field observations

The analyst may evaluate an existing roundabout to determine its performance and whether changes to its design are needed. Measurements of vehicle delay and queuing can be made using standard traffic engineering techniques. In addition, the analyst can perform a qualitative assessment of the roundabout performance. The following list indicates conditions for which corrective design measures should be taken (20). If the answers to these questions are negative, no corrective actions need be taken.

• Do drivers stop unnecessarily at the yield point?
• Do drivers stop unnecessarily within the circulating roadway?
• Do any vehicles pass on the wrong side of the central island?
• Do queues from an external bottleneck back up into the roundabout from an exit road?
• Does the actual number of entry lanes differ from those intended by the design?
• Do smaller vehicles encroach on the truck apron?
• Is there evidence of damage to any of the signs in the roundabout?
• Is there any pedestrian activity on the central island?
• Do pedestrians and cyclists fail to use the roundabout as intended?
• Are there tire marks on any of the curb surfaces to indicate vehicle contact?
• Is there any evidence of minor accidents, such as broken glass, pieces of rim, etc., on the approaches or the circulating roadway?
• Is there any gravel or other debris collected in nontraveled areas that could be a hazard to bicycles or motorcyclists?
• Are the vehicle speeds appropriate?