This five span bridge at Ashcroft replaced a sixty year old truss structure. The installation of the new 783 foot (233 metre) long bridge posed an erection problem as the Thompson River becomes a torrent during run-off. SOMERSET chose to launch the steel trapezoidal bathtub girders from both sides, closing in the middle.
The bridge was launched over a roller system that we designed to minimize the critical web buckling stresses. The rollers were mounted on rocker beams which also simplified passage of plate thickness changes. SOMERSET designed a falsework bent, an expandable spreader bar lifting system and a launching nose. An innovative hydraulic push-grip mechanism was conceived to replace the pulling hoist and reeving operation which was conventionally used. Later, a scheme to dismantle the old bridge was engineered and the truss was removed from the centre back, piece by piece.