The existing runway beams fixed to the underside of the Erskine Bridge were not suitable to accept the new suspended inspection gantries and needed to be replaced. Millar Callaghan presented the client with a tender document and a quality package and secured the contract.
To ensure the smooth and safe running of the new gantries, the profiled ends of the various sections of the 2620 meters of new runway beam had to join each other with a maximum of less than 1mm tolerance in profile. The only way this could be guaranteed was to order a special rolling of the material directly from the steel mill. As each section was rolled it was cut to size and both sides of the cut were given a unique identification number. The sections were then delivered to our Irvine workshop where the beams were put through an automated cutting system. This squared the ends and cut the beam to size to within a 0.5mm tolerance. To allow for the expansion and contraction of the runway beams, slotted holes were required at the connection points at the end of each beam.
When the runway beams had been manufactured they were sent to be hot metal sprayed, then a five coat paint system was applied. The beams were delivered to site along the cycle track of the bridge and lowered over the side of the bridge using a custom built and certified lifting hoist. Access to the new location was from the existing gantries. The existing gantry moved from one end of the bridge to the other installing and load testing the new beams and removing the existing runway beams as it passed under them.
On completion of this contract, Millar Callaghan’s quality department presented the client with a full quality package.
