The bill to repair the Louis-Hippolyte-La Fontaine tunnel, which connects the island of Montreal to the South Shore, is turning out to be more expensive than expected.

On Monday, Quebec's Transport Minister announced the new cost is $2.5 billion, which includes a $970 million increase to the contractor responsible for the work.

It was already known that a greater-than-expected deterioration of the tunnel's vault was the reason for an update on the construction costs.

In August 2022, François Bonnardel, then Minister of Transport, announced that an additional $900 million would be required to repair the Louis-Hippolyte-La Fontaine tunnel.

The government stipulated that this work would "ensure the durability of the infrastructure for 40 years without further major intervention." It reiterated this fact in a Monday press release.

The projected cost in 2020 was $1.4 billion, which included the large $1.1 billion contract between the ministry and the company responsible for the work, Renouveau La Fontaine (RLF).

It was mandated to design, build and finance the tunnel rehabilitation.

"The main interventions in the tunnel consist of major structural rehabilitation, upgrading operating equipment, redesign of service corridors and adding fire protection," said the release.

It indicates that additional interventions, costs related to the extension of the construction site and enhanced mitigation measures are included in the revised price.

In addition to the work on the tunnel, repairs are needed on the Souligny interchange and the concrete slabs on Highway 25 in both directions between Sherbrooke Street and Île Charron, totalling 13 km of roadway.

To prepare for the work, three of the six lanes of the Louis-Hippolyte-La Fontaine tunnel closed on October 31 and will remain closed until November 2025.

However, the feared traffic chaos seems to have been avoided.

Several measures to encourage the population to take an alternative route to the tunnel had been put in place by Quebec City.

The frequency of public transit in the Montreal area had been improved, and three incentive parking lots on the South Shore had been expanded, among other things.

After several weeks, the Government of Quebec gave a positive assessment.

Before the start of the rehabilitation project in July 2020, an average of 120,000 road users used the tunnel daily, compared to approximately 58,000 in the fall.

After a month of obstructions, the government concluded that mitigation measures and the cooperation of road users had reduced traffic in the tunnel by more than 50 per cent.

-This report by The Canadian Press was first published in French on March 20, 2023.