Ashcroft Bridge

This five-span bridge at Ashcroft, BC replaces a 60-year-old truss structure. The new bridge installation spans 783 feet in length and 280 feet in width, presenting a significant erection challenge as the Thompson River becomes a torrent during seasonal runoff.

KWH chose to launch the steel trapezoidal bathtub girders from both sides simultaneously, closing in the middle. The bridge was launched over a roller system that KWH and Somerset Engineering designed to minimize critical web buckling stresses. The rollers were mounted on rocker beams, which also simplified passage through plate thickness changes. Somerset engineered a falsework bent, an expandable spreader bar lifting system, and a launching nose to support the operation. An innovative hydraulic push-grip mechanism was conceived to replace the conventional pulling hoist and reeving operation.

Following completion of the new structure, KWH engineered a scheme to dismantle the existing bridge. The 280-foot main span cantilever deck truss was methodically removed from the centre back, piece by piece.