Issues in Flashing Operation for Malfunctioning Traffic Signals

R ese:irch for this article was prompted by a serious accident that occurred aiter a tripped conflict monitor c:iused an intersection signal to flash yellow for main street traffic and flash red for cross street traffic, just as the Manual on Uniform Truffic Control Devices suggests is normal. A visit to the accident site made it clear that accidents were quite foreseeable at this location if the intersection were allowed to operate in this flashing mode. If main-street volumes are too heavy for side-street traffic to enter or cross, or if visibility for sidestreet traffic is poor, how should an intersection be operated when a signal malfunction occurs? This article explores the current standards and practices for signalized intersection malfunctions and suggests some alternatives to the generally accepted flashing red/yellow practice.