Pedestrian “scrambled” intersections are intersections controlled by traffic signals that provide a crossing phase for pedestrians only, permitting simultaneous crossing in all directions of the intersection including on the diagonals. In other words, when the pedestrian phase is activated, all vehicular traffic in both directions is stopped, and when the vehicular phases are activated, all pedestrian crossing is stopped. Some municipalities have delineated scrambled intersections using decorative asphalt surfacing systems in patterns that mark the lateral and the diagonal pathways, i.e., a large “X” inside a square box.
In theory, this type of intersection design has two advantages. First, it is safer for pedestrians because it eliminates conflicts between pedestrians and turning vehicles. Second, it improves traffic flow efficiency. Diagonal crossing reduces two directional pedestrian travel time through the intersection. The flow of turning vehicles is more efficient because it is uninterrupted by pedestrian traffic.
But there is some inherent inefficiency. Conventional signalized intersections maximize the flow capacity of the intersection and the phases are shorter. Scrambled intersections not only require a separate pedestrian phase, but also a longer one to accommodate crossing the longer diagonal path.
Although scrambled intersections are many decades old and in use on four continents—Asia, Australia, North America and Europe—conclusions about their usefulness have been mixed. In 2006, researchers at the University of California Berkeley Traffic Safety Center (TSC) found that, generally, where vehicle volumes were high, scramble phasing reduced crashes.
In sites with high pedestrian volumes and high rates of conflicts between pedestrians and turning vehicles, scramble phasing has often proved to be effective in reducing pedestrian casualties. However, researchers in Europe have also found that scrambles resulted in more pedestrians crossing against the red light after losing patience during the extra-long waits. TSC researchers also found that scramble signalization increased the instances of pedestrian non-compliance with signals.
Other concerns relate to use of the intersections by blind and disabled people who depend, in some degree, on the sounds of other pedestrians and vehicles, all of which are more confusing in a scrambled intersection. Accordingly, new navigational systems with voice-recorded messages have been developed to provide additional information.
Some Canadian municipal governments are looking at this system with interest. The City of Toronto is planning a scrambled intersection at Yonge and Dundas, a particularly busy pedestrian and vehicle intersection. But concerns have been raised about the need for public education. As Ontario Safety League's Brian Patterson has noted, “We have a tough enough time getting people to walk between the white lines now at controlled intersections. If they start to confuse controlled intersections with scrambled intersections, we'll have people stepping out into traffic.”
One kind reader of Road Rules contacted us to mention that in the 1940’s, Vancouver had this system on at least one major intersection on Georgia Street (Georgia and Burrard?), and the people referred to it as “scatter lights”. The system was cancelled a long time ago, perhaps the early 1950’s? We could speculate that the reason for cancellation was the delay the system imposes on the movement of vehicular traffic.
Cedric Hughes of Hughes and Company Law Corporation, with contributions from Leslie McGuffin, LL.B., writes a weekly column on traffic advice for The VOICE. "The Road Rules" strives to provide helpful information about driving in British Columbia. We welcome your comments on our published articles and your suggestions for topics you would like us to address. Please email: eginter@hughesco.com. Phone: (604) 602-1818. Punjabi and Hindi: (604) 897-0207.
Email: cedric_hughes@hughesco.com
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