Harthill was the first service area in Scotland when it opened in 1978 and is the only service station between Glasgow and Edinburgh. In 2006 a £4.1m refurbishment programme was approved to modernise the service stations and replace the existing bridge.
Millar Callaghan were contracted to assemble the bridge sections in a lay down area running parallel with the northbound carriageway of the M8 motorway. Each section was raised into position with a crane and aligned with sockets to locate it in its exact position. When the sections were located a, full dimensional check was carried out to ensure that the length and profile of the arc were within the required tolerances. The joints were then heated with propane torches to remove any moisture and pre-heat the steel before the welding process could take place. The welding was carried out by fully qualified coded welders. On completion of welding and after a 48-hour cooling period, the welds were MPI & ultrasonically tested for defects. This process was repeated for all bridge sections. On completion the welded areas were repainted to match the bridge. The glass and electrical services were installed prior to the largest crane in Europe lifting the bridge into place on the 3rd October 2008.
Once the bridge was installed, Millar Callaghan completed the structure by carrying out works to staircases at either end allowing pedestrian access to and from each service station.
