A collaborative relationship between the City of Edmonton and one of Canada’s three university smart transportation laboratories continues to pay off for Edmonton drivers.
Wai Cheung, Edmonton Transportation Services’ technical specialist in advanced traffic analysis, says his relationship with Dr. Tony Qui, director of the U of A Faculty of Engineering’s Centre for Smart Transportation has once again proved invaluable.
Wai and Dr. Qiu cooperated this summer on a one-month pilot project that proved you can speed up rush hour traffic flow on the Whitemud Freeway by – yes! – actually asking drivers to slow down.
“There’s no way we could have done what we did without the U of A’s cooperation,” says Wai. “We couldn’t have done it without their brainpower.”
And for his part, Dr. Qiu says he and his graduate students could not have done their share without the real-time traffic flow data provided by the City, and the City’s ability to get varying ‘advisory driving speed’ messages to drivers on the freeway instantaneously.
The project involved real-time vehicle flow and speed data from sensors embedded in the freeway and its ramps. The UofA lab processed the data and provided ongoing variable speed recommendations to the City’s Traffic Management Centre, which then updated various advisory speed roadside signs on a westbound section of the freeway between 111 Street and 159 Street.
“When drivers slowed down, congestion at on-ramps reduced considerably,” says Wai. “There was more room between vehicles on the freeway for merging vehicles to slide safely into the flow of traffic.”
On-ramp congestion can cause drivers to brake quickly, creating a ‘wave’ of slow-downs that moves upstream on the freeway. Congestion often remains long after the initial event that causes it.
“The net effect of giving drivers what we call advisory driving speeds (ADS) was that average speeds during different portions of the peaks increased between 10 km/hr to over 30 km/hr,” says Dr. Qiu.
ADS also shortened the duration of overall congestion, from an hour to only 40 minutes. It also reduced travel time between 122 Street and 159 Street during peak flow periods by 10%, and sometimes even more.
During the pilot project – August 11 to September 4 – there was also a very significant drop in the number of vehicle collisions. In the three previous years, the same period usually saw five or six collisions at peak hours.
“During our pilot, there were only two collisions,” says Mr. Cheung.
One other benefit of ADS, Dr. Qiu points out, is the reduction in carbon emissions resulting from vehicle engines running for less time, and running more efficiently.
The City will continue processing the project’s results. At present, funding is not in place to make ADS a permanent service.