Work is underway to replace a section of aging gas line under a major artery in Coquitlam, and drivers are being warned to expect disruptions.

Crews and equipment are digging up pavement near Como Lake Avenue at North Road, and a partial lane closure is in effect in the area.

On Wednesday, work will begin on another section of the avenue between Blue Mountain and Porter Street.

Mayor Richard Stewart says traffic disruptions are to be expected with this kind of project, but adds drivers should be aware “this is going to be messy.”

"There are some intersections that are simply going to be a horrendous nightmare," Stewart said.

The project will replace a 20-inch line that’s been in service since the 1950s with a 30-inch line. The line runs through Vancouver, Burnaby and Coquitlam.

Last year, a section of First Avenue in Vancouver was temporarily shut down as part of the project.

A group of local businesses is now planning a class action lawsuit. Restaurant owner Federico Fuoco says businesses were promised they would be compensated if a loss could be proven, but told CTV that hasn’t happened.

"A lot of these businesses are small businesses. They can’t afford any loss, let alone 20 to 50 per cent," Fuoco said.

He said about a dozen businesses are prepared to take part in the legal action, and he plans to file the paperwork this month.

FortisBC spokesperson Grace Pickell said, "We do not offer direct monetary payments for business loss because this is a necessary gas line upgrade."

FortisBC is also under fire from Coquitlam’s mayor, who is concerned the city will be on the hook for repaving Como Lake Avenue once the work is done. He's also worried the city will have to pay to remove the old gas line Fortis plans to leave in the ground.

"We shouldn’t be subsidizing the operation of a utility," Stewart said.

Fortis said they will repair sections of road affected by the work, and added removing the old line once it’s no longer in service would be more disruptive.

“What the City of Coquitlam is asking for here is above and beyond what we do with any other municipality.” said Pickell, who also noted Fortis is seeking direction from the B.C. Utilities Commission on the city’s request.

Work is scheduled to continue in stages in the city till the end of the summer.

FortisBC says the line provides natural gas to more than 210,000 homes and businesses, and more than 30,000 of those are in Coquitlam.