Calgary's Innovative Traffic Solution

The City of Calgary has opened Canada's first "diverging diamond" traffic interchange in a bid to smooth traffic flow at a busy intersection in the city's south end.

A key goal of the interchange is to make it easier for motorists to make left turns without having to do so across several oncoming traffic lanes, and it achieves that goal in an interesting way.

What used to be an at-grade, multi-lane, four-way intersection where the north-south Macleod Trail crosses 162nd Avenue/Sun Valley Blvd now sees traffic on 162nd/Sun Valley vault Macleod Trail on an overpass that funnels vehicles to the left side of the bridge. From there, drivers looking to make a left onto Macleod Trail use dedicated lanes to do so; the arrangement also simplifies left turns from Macleod Trail onto the intersecting streets, while drivers continuing from 162nd onto Sun Valley (or vice versa) are shuffled back to the right-hand side of the roadway.

The diverging diamond design also takes pedestrians into account, with sidewalks and crosswalks to guide them across the new bridge.

Calgary city councillor Peter Demong told the Calgary Herald newspaper that the 100,000 people who will use the new piece of infrastructure every day will make the $78 million investment worthwhile.

Have a look at this animation by ISL Engineering, the company that designed and built the interchange, for a traffic's-eye view of how it works.