Fredericton is going to be a 'one bridge city' until late summer.

The Princess Margaret Bridge, one of Fredericton's two spans across the St. John River, closed Monday night. The bridge won't re-open until early-September.

The closure is expected to put a lot of traffic pressure on the capital city's remaining Westmorland Street Bridge.

The city is asking residents to use alternate ways to cross the river, including car-pooling, public transit, biking and walking.

"Twenty-thousand cars a day on the Princess Margaret Bridge is going to mean obvious traffic jams down in and around the downtown area and also on the north side ramp areas leading up in to the bridge," said Bruce Grandy, a Fredericton city councilor. "So it's going to have quite an effect."

The closure of the Princess Margaret is necessary for an $80-million refurbishment-project meant to extend the bridge's life for another 50 years. The Princess Margaret Bridge was built in 1957.

Refurbishment work on the bridge will include a replacement of the bridge's deck, a renovation of the bridge's 22 piers and two abutments, as well as complete structural steel sandblasting, strengthening and painting.

With files from CTV Atlantic's Andy Campbell