Major roadwork about to get underway on the Decarie interchange in Montreal promises to lengthen the journey for those heading toward the West Island.

Transport Quebec is adding a second lane to the Decarie ramp leading to Highway 40 West on the Metropolitan and will close the Côte-de-Liesse exit during the expected 11 weeks of work.

Instead, drivers will have to exit the Metropolitan at l’Acadie and take a detour along the service road that will be marked with 16 signs to help guide them.

Mario St-Pierre of Transport Quebec said GPS will be futile during the construction.

"People shouldn’t use their GPS, because it’s a newly created road," he said.

"What they have to do is follow the 16 signs that we’ve modified to help motorists go through the roadwork."

CBC traffic reporter Jennifer Allen said motorists should leave a fair amount of extra time to get to where they’re going.

"Along that route there are several traffic lights as well as ongoing roadwork around the Decarie interchange itself, so it’s just going to be a nightmare," she said.