FLEXIBILITY IN CLEARANCE-INTERVAL TIMING

Interest in flexibility in signal clearance-interval timing appears to come from within the profession, rather than from the community. There is some evidence that informed road users would call for less flexibility and more-positive clearance of moving streams before waiting vehicles are shown a green. The far-side pedestrian is particularly at risk. If the traffic engineer prefers not to use a red clearance interval, there are some innovative solutions that could help the far-side pedestrian, including a delayed WALK signal and the animated eyes light-emitting diode (LED) display. Some situations call for extremely high values of yellow or red clearance timing. A rational procedure exists to provide flexibility in yellow timing for approaches with high speeds on steep downgrades. However, uncertainty emerges when trying to deal rationally with very long calculated red clearance intervals at wide intersections with low approach speeds.