Major roadwork is coming to the Louis-Hippolyte-Lafontaine Tunnel but authorities are promising it won’t start until other major projects are finished.

On Tuesday, the Quebec transport ministry unveiled an action plan for major structural upgrades to the tunnel. However, the four-year project won’t get underway until after work is completed on the new Champlain Bridge and the Turcot Interchange, meaning ground won’t be broken until 2019 at the earliest.

Though two of those years will mean significant changes to traffic and two would be less so, at no point with the tunnel be closed entirely.

Reserve bus lanes will be added to help mitigate those effects and parking will be added on both ends to encourage people to leave their cars behind.

Much of the work will be focused on the renovating the interior of the tunnel, including upgrading the fire protection. Since 2000, the tunnel has been the site of 13 fires, several of them serious.

Among the work that will be conducted is the replacement of concrete slabs on Highway 25 in both directions as well as on both sides of the tunnel between the Sherbrooke interchange and Charron Island.

“The protection we want would have to resist 1200 Celsius for two hours, so it's a very robust protection that we’re going to have,” said Transports Quebec spokesperson Alexandre Debs.

While no price tag has yet been put on the project, officials said renovations would be far cheaper than a replacement, which would have cost as much as $3.5 billion.

This year marks the 50th birthday of the structure and officials said the work is aimed at ensuring the longevity of the tunnel into the foreseeable future.

“It’s possible to replace it with another tunnel, but the cost would be extremely high. We have an assessment that it’s in good shape and we think we need to rehabilitation now in order to have at least another 40 years,” said Debs. “The structure is quite solid.”

No company has yet been selected to spearhead the project but the transport ministry said whichever company does end up taking on the contract would have to finance the project themselves and would face serious financial penalties for any delays. 

“When you associate the design with the build together, we share the risk with the partner of the project,” said Debs. “It's like a double insurance.”