Macleod Trail and 162 Avenue Diverging Diamond Interchange

Calgary, AB

An historic event, the decision to build the first DDI in Canada was made for a variety of reasons including increased safety and capacity, and ease of construction. Land had been reserved in the area decades ago for a partial cloverleaf interchange but it did not stand the test of time and new thinking was required. ISL had evaluated DDIs at a number of locations in Calgary before but it was never the right fit until 162 Avenue.

The Design

The design promotes a free flow of traffic both below and above the new overpass. Unlike a standard diamond interchange, traffic is divided based on direction – all left-hand traffic is funneled to the left side of the road and can turn onto the major thoroughfare without waiting at a stop light or worrying about crossing oncoming traffic.

Benefits During Construction Sequencing

The construction sequencing allowed for the project to remove the traffic signal from Macleod Trail in October 2016, tremendously improving traffic flows nearly a year before the interchange was finished.

Calgary’s Unique Context

The team thoroughly surveyed current practices in DDI implementation in the United States and paid careful attention to getting every detail right for Calgary’s unique context including driver behaviour and climatic conditions.


This major milestone was achieved because of the close collaboration between ISL, The City of Calgary and Graham Infrastructure. The City and their senior leadership team in particular were instrumental, providing expertise across many departments and motivating the team by providing strong support to successfully implement this new and innovative solution.

Award Winning Interchange

The DDI received a 2018 Minister's Award for Transportation Innovation in Construction as well as a 2018 Consulting Engineers of Alberta (CEA) Award of Excellence in Transportation Infrastructure - Roads, interchanges, airports, mass transit and ports and a 2018 CEA Award of Merit for Project Management.

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