The street outside Toronto's Union Station is set to undergo a big facelift.

The city is beginning reconstruction of the station's pedestrian bridge, at an estimated cost of $4 million, as part of the revitalization of the historic landmark.

The structure runs east-west between the Front Street sidewalk and the front of the station building.

Mayor David Miller told a news conference outside Union Station on Friday that the development is a top priority for the city and that the structure will be restored for accessibility and safety.

"Our plan is to demolish the existing bridge and replace it with another that captures the essence, style and heritage of Union Station.

"The reconstruction of the bridge is expected to be completed within approximately 15 months — and during this time we hope to have the support, patience and co-operation of all passengers who use this station for their travels," Miller said.

The city estimates about 200,000 people go through Union Station every day, making their way onto the TTC, or GO or Via trains.