Highway 742 to Kananaskis targeting mid-August reopening after June rockfall closure
Work to stabilize the slope and install rockfall barriers began July 21. The highway has been closed for two months after boulders the size of small vehicles fell across the road.
Sources · local media reports
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A popular highway accessing Kananaskis Country through Canmore is targeting a mid-August reopening after a rockfall two months ago left it impassable.
On June 1, roughly 200 cubic metres of rock fell from the East End of Rundle, scattering boulders the size of small vehicles across Highway 742—commonly known as Spray Lakes Road, the Canmore Hill, or the Smith-Dorrien Trail. The rockfall narrowly missed a vehicle. Work to remove debris and stabilize the slope began July 21.
Alberta's Ministry of Transportation and Economic Corridors is installing rock bolts to secure unstable sections and adding temporary rockfall barriers to prevent future rock debris from hitting the road. The significant rainfall in late May and early June increased rockfall risk in the area, prompting the comprehensive mitigation plan. The work is expected to be completed by mid-August, pending weather conditions.
The closure has cut off normal access to Grassi Lakes, a well-visited tourist spot in Kananaskis that was closed June 10 for public safety. Visitors must take a roughly two-hour detour north on Highway 40 and past Spray Lakes to reach the area. Geotechnical engineer Renato Macciotta from the University of Alberta said the mitigation work being done is "very effective, and in this case would be very cost effective."
The last major rockfall on the highway occurred in May 2013 closer to the Ha Ling Peak parking lot, an incident that narrowly missed a vehicle and a group of people. Research estimates a one- to 10-cubic-metre block falls from Mount Rundle roughly every 10 years, while a 10- to 100-cubic-metre rockfall occurs once every 100 years or more.
By the numbers
When did the rockfall close Highway 742?
On June 1, 2026, roughly 200 cubic metres of rock fell from the East End of Rundle across Highway 742, closing the road to Kananaskis Country.
When did stabilization work begin on Highway 742?
Work to remove debris and stabilize the slope began on July 21, 2026.
When is Highway 742 expected to reopen?
Highway 742 is targeting a mid-August 2026 reopening, pending weather conditions.
