By Ryan McGreal
Published February 20, 2009
this blog entry has been updated
RTH reported earlier this week that the proposed pedestrian scramble intersection was removed from the York Boulevard Streetscape Master Plan, as the result of a traffic study conducted in January by the Public Works Department's Traffic Engineering and Operations office.
I contacted Hart Solomon, the traffic engineer in charge of the study, for more information. He explained that the study, which modeled traffic flows based on standard traffic signal timing calculations, found that the lane reductions combined with the scramble would back traffic up as far as Queen Street after an hour of peak use.
The reason the scramble is so inefficient is that all vehicular traffic remains motionless when the pedestrians cross in the scramble operation, and time has to be provided for pedestrians to cross the road diagonally, so that means a fairly long time without any vehicles moving. In the normal operation, vehicles are always moving in one or the other direction (except for the amber light, of course), so time is used much more efficiently.
I replied to ask him whether the model assumes or calculates that total traffic volume will remain the same - after all, demand for lane capacity is flexible and some people will choose alternate routes or different times to avoid congestion - but did not receive a subsequent response in time for this article. Update: Read Hart's response in a subsequent blog entry.
Solomon also argued that the pedestrian scramble is "not particularly friendly to pedestrians."
A scramble intersection works on a three-stage cycle: vehicular traffic flows one one directional axis (e.g. east-west), and then on the other directional axis (e.g. north-south), and then all traffic stops and pedestrians can cross in any direction.
During the first two stages, vehicles have the right of way and pedestrians are not allowed to cross. As Solomon pointed out:
This means that if a pedestrian arrives at the wrong time, he or she can be standing still with nowhere to cross for quite a while. At a normal signal, one always has the option of crossing in one or the other direction.
Councillor Bob Bratina (Ward 2, downtown) has announced that he will attempt to have the scramble intersection re-included in the final York Blvd Plan before it goes to Council for approval.
Update: Hart Solomon replied to my query on Monday. You can read his response in a subsequent blog entry.
You must be logged in to comment.