In a highly unusual operation, contractor Amec has used a new steel bridge structure as a gantry in the £28M removal and replacement of Doncaster's old North Bridge, completed last weekend. North Bridge carries a major road over the East Coast Main Line and Doncaster Canal. To minimise the amount of craneage, Amec cut off the existing bridge's parapets and used it to launch two new 105m long steel trusses.
These were connected with cross-trusses and equipped with temporary longitudinal runway beams before being jacked 2.75m above the old structure. The old bridge was then cut up into nine sections, the largest weighing 140t, which were slid out along the runway beam and lowered to the ground. The runway beams will now be removed before the new bridge is lowered onto permanent bearings and a reinforced concrete deck installed.