Quebec is suing a construction consortium after blaming the companies for a partial structural collapse in Montreal's Viger Tunnel.

The province has announced legal action against CIMA+, Dessau and SNC-Lavalin to seek financial compensation for the July 2011 paralume collapse in the heavily travelled downtown tunnel.

The announcement follows the release of a report that blames the consortium for what it describes as ill-planned maintenance work on the Ville-Marie Expressway structure.

The report says maintenance work did not conform to provincial safety norms.

The tunnel, built in 1972, was up to code when it was built, said Quebec Transport Minister Pierre Moreau.

But an overheard concrete beam could not support repair work done last year that involved workers using pressurized water.

A concrete grid serving as a sun shield detached from the tunnel ceiling on Sunday, July 31, near the city hall exit.

Given it was a weekend morning, the tunnel was virtually empty when the 25-tonne concrete slab crashed on road.

At the time, then-Transport Minister Sam Hamad first blamed the collapse on maintenance work being done in the tunnel.

He later backed away from that assertion, saying that his blame wasn’t specific to the maintenance consortium.

In October, Transport Quebec removed the remaining 134 grids – also known as paralumes – from the tunnel after engineers found the shades and the beams that hold them to be in serious disrepair.

Paralumes were also removed from the Louis-Hippolyte-Lafontaine Tunnel last fall.

The Ville-Marie Expressway handles 100,000 vehicles daily.