The City of Calgary says a unique southeast traffic overpass, the first of its kind in Canada, has resulted in fewer crashes and far fewer collisions involving injuries.
A municipal diverging diamond interchange, which opened in 2017, replaced the traditional intersection at Macleod Trail and 162nd Avenue/Sun Valley Boulevard S.E.
According to the city, there’s been a 75 per cent decrease in injury crashes at the interchange (only five from 2018-2020 compared to 20 from 2014-2016) and 38 per cent fewer crashes overall (115 crashes between 2018 and 2020 compared to 186 crashes between 2014 and 2016).
“The big thing is all of the turning movements are taken out of the signalized intersection,” Tony Churchill, City of Calgary coordinator of mobility safety, told Global News. “The signalized intersection is a simple two-direction through movement … all of the turns happen on the side.
“It’s less likely that you’re going to have that high-speed angle impact that results in severe injuries.”
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City officials say the interchange was designed to reduce traffic congestion while improving safety for motorists, cyclists and pedestrians. The weave design makes it so left-hand turns are no longer made across lanes of oncoming traffic.
“This layout has been used extensively throughout the U.S. and in Europe,” explained Churchill. “It can reduce the cross-section of the bridge and really takes those left turning movements out which we know are some of the high-severity, high-risk conflicts at signalized intersections near interchanges.”
Churchill says the diverging diamond interchange approach is unlikely to replace existing interchanges in the city, including those along Deerfoot Trail, as its adoption normally works best in new construction projects rather than retrofits. He adds that the safer diverging diamond method is a tool in the toolbox for engineers designing future highway interchanges.
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