News / Calgary

Reducing speed limit on Calgary's Deerfoot Trail could aid congestion

A University of Calgary master's student has computer models showing the effect of variable speed limits

Deerfoot Trail is already over its intended capacity at rush hour, but reducing the speed limit at peak times could help, according to a University of Calgary master's student.

ELIZABETH CAMERON / Calgary Freelance

Deerfoot Trail is already over its intended capacity at rush hour, but reducing the speed limit at peak times could help, according to a University of Calgary master's student.

A University of Calgary student has honed his numbers on installing variable speed limits (VSL) on the Deerfoot Trail, and he's convinced slowing down at rush hour would save everyone time on the road.

Karan Arora, a master's student at the Schulich School of Engineering, has been running traffic models, looking at ways to improve the flow on Deerfoot Trail, specifically between 17 Avenue in the south and Airport Trail.

Arora said Calgary is one of Canada's fastest growing cities, and more traffic on the Deerfoot is to be expected as the city grows. He's interested in finding ways to stretch the capacity without breaking the bank.  

His models are showing that having a variable speed rate would make the stretch of highway 29 to 31 per cent safer.

Arora also has another trick up his sleeve to smooth your commute along. He's suggesting the use of the left lane shoulders as a temporary lane which would be used only for rush hour traffic, or for emergency vehicles.

He said changing those shoulder lanes to temporary lanes would be cheaper because highway traffic lanes are 3.5 metres, and the shoulder is already three metres wide.

"Changing shoulder lanes to an additional lanes is going to cost less than adding an extra lane because the foundation is already there, they just need to pave an additional half meter," he said.

Using VSL and rush-hour lanes would save drivers, on average, 11 minutes of travel time, according to Arora's study.

Going slower to get everyone movig faster may seem counterintuitive, but professor Lina Kattan, Arora's supervisor, used the example of a kitchen funnel.

"If you're pouring liquid in the funnel, you've got a bottleneck," she said. "Do you pour all your liquid at once, or do you slow down?"

The question is – will the City Calgary be able to use Arora's advice? Not anytime soon, according to Coun. Sane Keating, recently re-elected to serve as chair for the city's transportation and transit committee.

He said the Deerfoot is still under the province's control, and will be for some time.

"My understanding is that once the ring road is complete, the province will be turning the Deerfoot over to the city at that time," said Keating.

Once that happens, the city might be able to explore options such as VSL.

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