Pre-fabs to span Ontario bridge construction

MTO, in partnership with an Ontario contractor - Leo Alarie and Sons Limited, successfully used prefabricated bridge technology to save time and money. Pre-cast full roadway depth/width concrete slabs were used for the Passe-à-Fontaine Bridge approximately 20 km northwest of the Town of Hearst. Savings from adopting the proposal reached nearly $30,000.

Crossing the French Creek at the Hanlan Narrows, the original bridge was a 36.5 meter single-span Bailey bridge. To avoid in-water construction and disruption of a sensitive pickerel habitat, the new bridge abutments were constructed within the existing bridge approach and a Retained Soil System (RSS) wall.

The tendered design for the replacement bridge was a single lane, single-span steel girder bridge and featured an exposed concrete deck and semi-integral abutments founded directly on bedrock. The contractor’s change proposal for a precast full roadway depth/width deck with a foundation on bored mini piles embedded in the bedrock was approved by MTO after a comprehensive review.

During construction the existing Bailey bridge and substructure were removed, the road grade was raised to provide structural, navigational and hydraulic clearances, and a new temporary single-lane structure was installed. The full roadway depth/width panels were fabricated and transported on flat bed trailers without the need for oversized load permits. A Cat 970 Loader placed the panels on steel girders and, once sheer bolts were installed, cast-in-place closure strips were poured. Overall quality is improved when concrete is placed in a controlled environment, under optimal conditions and under strict quality assurance standards. Using this prefab system cut six months from the construction schedule and with further industry experience is expected to have even greater efficiencies.

"We're glad to see a contractor proposing innovative methods to reduce on-site construction time," says Alain Beaulieu, coordinator for MTO's Prefabricated Bridge Systems Implementation Team. "This technology can reduce on-site construction time, resulting in reduced worker exposure to live traffic." MTO has since included prefabricated bridge technology in several projects to promote industry knowledge and experience.