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How to Regulate Traffic in a Sustainable World


Busy intersections have been regulated by traffic lights for more than a century. In 1868, downtown London had so much horse and wagon traffic that a British railroad signal engineer designed the first traffic semaphore to regulate movements near the Parliament. The device was indeed the first traffic “light”, as lenses in the semaphores where lighted by gas lanterns at night. Besides traffic regulation, one of the goals behind the creation of the device was the protection of pedestrians. Various manually-operated devices appeared in the following decades, usually manned by policemen whose whistle took care of the clearance interval. In the golden years of the horseless carriage, rapidly increasing traffic required a new way to regulate movements. The first electric traffic lights appeared in 1912, but only in 1914 did the first traffic light controller made in way to Ohio streets. The blueprint for modern traffic signals, the three-color signal head, bowed in 1920. The first dedicated pedestrian signals appeared a decade later, and a prototype that defined a clear, exclusive pedestrian phase was tried out in New-York in 1934. The Big Apple also saw the first document “WAIT” / “WALK” signals in 1939. In the following years, with the ever-increasing vehicular traffic, pedestrians made little gains at traffic signals despite prodigious advancements in technology. More and more, they had to push buttons or step on pressure plates to get the “WALK” signal, and even then pedestrian signals mostly worked parallel to vehicular signals, eschewing any form of priority by function. Fast forwarding to the 21st century, walking has come back in force as the backbone of active transportation, as society strives to promote more sustainable transportation. Transit is getting the lion’s share of attention and research in the traffic field, while cycling is integrated into public infrastructures through upgrades or “complete streets” rebuilds. Pedestrians … are still on the sidewalk. What can be done to help them put a foot forward in the transportation hierarchy? Exclusive phases are back in vogue and now called “scrambles”. Countdown timers remove hazardous situations by clearly indicating how much time is left before the “DON’T WALK” signal comes up. Visually impaired pedestrians benefit from improved mobility in urban centers thanks to standardized Accessible Pedestrian Systems. Modern traffic controllers offer tremendous computing power, giving traffic engineers increased flexibility when orchestrating movements at an intersection. Measures that both protect the pedestrian and allow vehicular traffic to progress elevate the status of walking while not impeding the flow of transit and other vehicles are hidden in that computing power, and have been there for years. This paper relates the historical steps in the pedestrian signalling world. It is intended as a toolbox of pedestrian-friendly measures for practitioners, some actively putting walking front and forward … at no cost. Measures like the Leading Pedestrian Interval and the Walk phase extension are simple functions available in modern traffic controllers. Other measures like the pedestrian countdown timer and the “Through Arrow Leading Walk Interval” are simple to retrofit during traffic signal upgrades and are of much benefit to pedestrians. 

Conference Paper Details

Session title:
Daniel Beaulieu
Road safety