Go slow to go fast might just work on Deer­foot Trail

Calgary Herald - - FRONT PAGE - SHAWN LO­GAN

Even the lead au­thor of the re­port ad­mits his find­ings seem counter in­tu­itive — slow­ing down traf­fic on some of Calgary’s busiest ar­ter­ies could re­duce the amount of time com­muters spend tap­ping their brakes in gridlock.

But Karan Arora, a mas­ter’s stu­dent at the Univer­sity of Calgary’s Schulich School of En­gi­neer­ing, said the use of vari­able speed lim­its on ma­jor thor­ough­fares like Deer­foot Trail could shave sev­eral min­utes off the av­er­age com­muter’s drive time dur­ing rush hour, and make those trips about 30 per cent safer as well.

“We know that vari­able speeds could be an im­prove­ment for free­ways like Deer­foot Trail in Calgary,” he said.

“What we’re try­ing to do is slow down traf­fic be­fore reach­ing a bot­tle­neck and then speed­ing them up when they’re leav­ing that bot­tle­neck.”

The the­ory, which has been im­ple­mented in Western Europe and parts of the U.S., is sound. But due to pro­vin­cial Traf­fic Safety Act leg­is­la­tion, it hasn’t been pos­si­ble to en­act in Calgary, de­spite it be­ing con­sid­ered a pos­si­ble an­ti­dote to gridlock for as long as a decade.

Arora’s re­search ze­roed in on a 13-kilo­me­tre stretch of south­bound Deer­foot, Calgary’s pri­mary north-south net­work, be­tween Air­port Trail and 17th Av­enue South.

Un­der ideal con­di­tions, it found driv­ing speeds dur­ing gridlock would im­prove by about five min­utes, a num­ber that would rise to nearly 10 min­utes dur­ing off-peak hours.

What­ever road­way uses the ini­tia­tive would need over­head dig­i­tal sig­nage every one or two kilo­me­tres to en­sure driv­ers were trav­el­ling at the op­ti­mal speed, which would fluc­tu­ate every minute based on real-time traf­fic data to ei­ther slower or even faster than the posted limit.

In 2010, Wash­ing­ton state spent $65 mil­lion im­ple­ment­ing vari­able speeds and lanes on three ma­jor high­ways, aim­ing to im­prove both travel times and safety.

Ac­cord­ing to a 2014 re­port, the ini­tia­tive im­proved both travel speeds dur­ing rush hour by as much as 24 km/h and re­duced col­li­sions over a six-year pe­riod by four per cent.

Arora said travel times on the study sec­tion of Deer­foot could be im­proved even fur­ther by open­ing up the hard shoul­ders to traf­fic dur­ing peak hours. Es­sen­tially open­ing up an ex­tra lane would in­crease traf­fic flow by 28 to 38 per cent, with a 23 to 31 per cent re­duc­tion in peak hour travel time, rep­re­sent­ing a time’s sav­ing of 11 min­utes.

He noted it could ex­tend the life of Deer­foot by 25 to 30 years.

As with Wash­ing­ton state’s vari­able speed high­ways, the over­head signs would also warn driv­ers of poor weather con­di­tions or col­li­sions ahead, al­low­ing traf­fic to flow away from snarled ar­eas.

Troy McLeod, direc­tor of the city’s roads depart­ment, said the no­tion of vari­able speeds has been on the city’s radar since 2007, but pro­vin­cial leg­is­la­tion made it im­pos­si­ble to even do a pi­lot project.

With draft leg­is­la­tion of the province’s new city char­ter in­clud­ing al­lowances for Calgary and Ed­mon­ton to es­tab­lish their own speed lim­its with­out the need for pro­vin­cial ap­proval, McLeod said a pi­lot project may be pos­si­ble in the near fu­ture.

“The new city char­ter could af­ford an av­enue to look at that,” said McLeod, not­ing the free flow­ing por­tions of Glen­more Trail and Crowchild Trail may be ideal ar­eas to test out the tech­nol­ogy.

“There are proven ben­e­fits both for safety and con­ges­tion man­age­ment.”

McLeod added with ex­pected ad­vance­ments to au­to­mated ve­hi­cle tech­nol­ogy, the ini­tia­tive may work even bet­ter by fur­ther con­trol­ling speeds to en­sure they are op­ti­mized.

Lina Kat­tan, a pro­fes­sor of civil en­gi­neer­ing at the Schulich School who over­saw the project, said the con­cept may not be as far away from Calgary road­ways as peo­ple think, and could turn out to be a ma­jor boon for of­ten curs­ing com­muters.

“We’ve worked very closely with the city and the city is very in­ter­ested in this,” she said.

“We’re not only talk­ing about im­prov­ing travel time, but safety as well.”

En­gi­neer­ing mas­ter’s stu­dent Karan Arora has com­pleted a study at the Univer­sity of Calgary show­ing how vari­able speed lim­its on Deer­foot Trail and other ma­jor routes could im­prove both traf­fic flow and safety.


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