On-Site Magazine

Major sections of Hwy. 400 bridge swapped out over two weekends to make way for new Toronto LRT

By On-Site Staff   


Months of prefabrication work, intricate scheduling and the assistance of a self-propelled modular transporter with about two-dozen axles, allowed construction crews in Toronto this month to quickly replace a pair of vital bridge decks over the course of two busy weekends.

Mosaic Transit Group, the P3 consortium responsible for the new Finch West Light Rail Transit project, swapped out the bridge decks that carry Highway 400 over Finch Avenue at the north end of Toronto. The team took care of the southbound bridge between June 12 and 15, and completed the other half of the rapid bridge replacement (RBR) work June 19 to 22, according to transit agency Metrolinx.

The RBR method cuts down drastically on road closure times — an important feature along the busy north/south-running highway. It has been used on several major projects in the province in recent years.

The replacement work created few disruptions for commuters, but construction crews have been preparing for the closures for months, prefabricating the new bridge decks in laydown areas adjacent to the highway. Once the pre-built bridge decks were ready, crews positioned a self-propelled modular transporter (SPMT) below the old southbound deck, cut away the supports and removed the mass of concrete and steel. The Mammoet SPMT then lifted the new deck, weighing some 1,500 tonnes, into place, where it was secured, reconnecting the highway.


A week later the Moasic team, which is made up of ACS Infrastructure Canada Inc., Aecon Group Inc. and CRH Canada Group Inc., repeated the process for the matching six-lane northbound section, measuring approximately 30 by 40 metres.

The complex bridge work is an essential part of Ontario’s Finch West LRT project, as the new rail line will run along Finch Avenue under Hwy. 400. It is one of several early stages of work on the light rail line that will eventually span 11 kilometres and include 18 stops.

Construction on the $2.5 billion project is expected to run through 2023.

Watch the self-propelled modular transporter rotate the southbound bridge deck during the first phase of work


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