Calgary’s first Diverging Diamond Interchange shown to have greatly improved safety for motorists

diverging-diamond-interchange-stats-infographicIn just five years of operation, Canada’s first Municipal Divergent Diamond Interchange (DDI) in south Calgary has seen a 75 per cent reduction in injury collisions and a 38 per cent reduction in total collisions.

Located at Macleod Trail and 162 Avenue S.E., the interchange was designed and built to improve safety for the people who drive, walk and ride in the area. About 70,000 vehicles use Macleod Trail every day at this location and about 35,000 on 162 Avenue/Sun Valley Boulevard S.E.

“In five years, serious injury collisions dropped from 20 collisions to five, which is in line with what we expected for safety outcomes," says Tony Churchill, coordinator, Mobility Safety at the City of Calgary. “These unique infrastructure developments are proven to improve traffic flow and reduce harm on our roadways. The benefits for Calgarians in avoiding injury or death are worth the investment and inconvenience during construction.”

Motor vehicle collisions are also costly to the people involved and to society as a whole. The City reports a 68 per cent reduction in the cost to society since 2017 for injury collisions at the interchange.

“We don’t always think beyond the victims or their families when it comes to car crashes. Society as a whole is also impacted whether it’s because of too many incidents causing an increase in everyone’s insurance premiums, medical costs and strains on health care, legal resources to deal with court cases, or decreased earnings because of disability, long-term impairment or loss of work,” says Churchill.

We adopted Vision Zero in 2019 — a global movement to end traffic-related fatalities and serious injuries by taking a systemic approach to road safety. Our Safer Mobility Plan (2019-2023) outlines the long-term vision of mobility free of major injuries and fatalities with the short-term target reduction of 25 per cent reduction by 2023.

“We’re currently trending on track or better than the expected 25 per cent reduction, and we’re hopeful we’ll reach our short-term target by end of 2023. Whether you drive, bike, walk or roll, Calgary’s roads are getting safer, and we still need to look out for each other,” says Churchill.

In 2021 in Calgary, there were 14 fatal collisions, 2,094 injury collisions and 24,483 property damage only collisions on Calgary roads. The 2021 societal cost of these collisions was estimated to be $956 million.

Read the City of Calgary Safer Mobility Plan Annual Briefing.

What’s a DDI?

A DDI is a unique and modern interchange design that helps reduce traffic congestion and improve safety for people who drive, cycle or walk.

It allows two directions of traffic to temporarily cross to the left side of the road. It moves high volumes of traffic through an intersection without increasing the number of lanes and traffic signals.

Left turn movements are safer and more efficient because they do not cross opposing traffic.

For people unsure how to navigate the interchange, The City developed this video to illustrate how to drive the DDI.

More information is available at