B.C. Transportation Minister Claire Trevena says widening and realigning a 4.8-kilometre stretch of the Trans Canada Highway east of Golden, B.C., is now expected to cost $601 million — an increase of a third over the 2016 estimate.

In 2016, former minister Todd Stone announced that the fourth phase of the Kicking Horse Canyon project was expected to cost $450 million, which he said was likely to make it the most expensive roadwork per kilometre in Canadian history.

On Thursday, Trevena said the cost had increased due to a hot construction market across the province, increased labour and material costs, a re-allocation of interest and new design considerations.

"Advanced technical work has determined the need for significant changes and upgrades to the design concept," she said.

Trevena said the government has now begun accepting bids for the project, which will widen the stretch of highway between West Portal and Yoho Bridge to four lanes, and will result in complete closure of the road for weeks at a time.

She said the plan will be to avoid disruption to traffic during the busy summer months — when as many as 10,000 vehicles pass through the canyon each day — and during the ski season.

Detours will take Highway 93 between Castle Junction, Alta., and Radium Hot Springs, B.C., reconnecting to Highway 1 via Highway 95 — a route that would add more than an hour to most trips.

Construction on the section of highway, part of a wider, 26-kilometre upgrade, is expected to be challenging. It's scheduled to start next summer and be completed in the winter of 2023-24.

Notorious stretch of highway

The section of two-lane highway is notorious for crashes, with the collision rate triple the average of other, similar highways in B.C., according to the ministry. Avalanches are also a concern in the Kicking Horse Canyon.

"This last two-lane section has 13 bends, with rock faces on one side and the canyon on the other. There's hardly enough room for people to safely change a tire if they need to," said Trevena.

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