Demolition crews are working at the Margaret Avenue bridge in Kitchener as the teardown of the bridge deemed to be too unstable to be left standing begins.

The bridge was closed in June when it was declared unsafe for vehicles and people, and should be fully demolished by early December, according to Kitchener city staff. 

"This is a complicated demolition and building a new bridge over those active railways will also be complicated," said Kitchener's director of engineering Barbara Robinson. 

A new bridge will be built in its place by the spring of 2015 at an estimated cost of $6 million. 

"We're not expecting this to be a sexy bridge," said Robinson. "It's a major thoroughfare, we need to get a bridge up quickly." 

Robinson said the new bridge will have improved clearance over the active GO and Via Rail tracks to meet present standards. 

"Either we're going to be raising the bridge up or the depth of the bridge will be narrower than it is now," said Robinson. 

The demolition will be handled by Bel-Air Excavating and Grading Ltd. from Cambridge, who were awarded the contract by the city.

The city will put out a request for proposals for consultants for the rebuild of the bridge in the next month. The city hopes to have a consultant in place by the end of November.