The purpose of this research task for 2010-2011 is to extend the Smart Signals enabling concepts to countdown pedestrian signals. Present countdown signals display the incorrect time available to complete a crossing if the signal timing changes for the pedestrian clearance interval. In addition, the countdown display can become misleading if the electronics in the pedestrian signal misoperate. These failure modes are undetectable by the malfunction management unit (MMU) that is normally responsible for ensuring correct traffic signal operations.
The primary goal is to use the safe-fail operations developed for the AAPS pedestrian stations and develop a new pedestrian signal that allows the validation of controller operations that generate the countdown signals. We plan to leverage the hardware and a significant portion of the software developed for the AAPS to control a new low-voltage LED-based countdown pedestrian signal. There are two significant challenges to achieving the anticipated improvements: getting the real-time pedestrian clearance interval timer information from the traffic controller and providing a means of signaling the MMU of a potential life-threatening malfunction. Preliminary discussions with traffic controller experts indicate that this capability does not exist but is possible with traffic controller software and hardware modifications.