Nearby vehicular and pedestrian signals

Another method of metering is the use, with appropriate timing, of a nearby upstream signalized intersection or a signalized pedestrian crossing on the subject approach road. Unlike pure entry metering, such controls may stop vehicles from entering and leaving the roundabout, so expected queue lengths on the roundabout exits between the metering signal and the circulatory roadway should be compared with the proposed queuing space.

Because of additional objectives and constraints, metering by upstream signals is generally not as effective as direct entrance metering. However, a signalized pedestrian crossing may be desirable on its own merits. More than one entrance can be metered, and the analyst needs to identify operational states and evaluate each one separately to provide a weighted aggregate performance measure.

When disabled pedestrians and/or school children are present at a high-volume site, a pedestrian-actuated traffic signal could be placed 20 to 50 m (65 to 165 ft) from the yield line. This longer distance than at an unsignalized crossing may be required because the vehicle queues downstream of the roundabout exit will be longer. The trade-offs for any increased distance requirement are increased walking distances and higher exiting vehicle speeds. An analysis of signal timing will be needed to minimize queuing of vehicles into the roundabouts.