MONTREAL—Traffic headaches are expected to last months as city crews begin tearing up roads around the McTavish reservoir on Wednesday.

A stretch of Pine Ave. will be closed until December as century-old water mains and sewer pipes are replaced around one of downtown’s largest reservoirs.

“This is work that was long necessary as the average pipe is at least 100 years old,” said Montreal spokesman Jacques-Alain Lavallee. “It’s a huge project because it’s over $16 million and it serves over 500,000 people in seven boroughs. This is something that we need to take care of.”

Work will take place from 7 a.m. until 10 p.m. and will continue through the winter, said Lavallee, to ensure it is completed as quickly as possible.

During the first phase of the project, Pine Ave. between McTavish St. and Doctor-Penfield Ave. will be closed to traffic. The city took special precautions to see that access to the Royal Victoria Hospital remains fluid.

Access to the Royal Vic’s third parking lot will be closed for the duration of the project. East and westbound traffic will be allowed on Doctor-Penfield Ave. to help relieve congestion.

The second phase of the project will see the closure of Doctor-Penfield Ave. just south of Pine Ave. Running from December to March 2013, circulation on Doctor-Penfield Ave. east of McTavish St. will be limited to local McGill University traffic.

The final phase will run from April to August 2013 and will see the closure of Pine Ave. between Doctor-Penfield Ave. and Durocher St.—just at the foot of the Pine-Park interchange. No eastbound traffic will be allowed on that section of Pine Ave. during the construction work.

Work was carried out on the affected section of Pine Ave. in 2011, however according to the city that work was to prepare the avenue for this major project.