Standing for over 100 years, Enterkine Viaduct in Annbank has provided a rail link from Ayrshire open-cast mines to the main rail network. A major structural refurbishment was carried out in 2008. This refurbishment consisted of replacing over 340 tonnes of structural supporting beams over the full length of the viaduct.
A full survey of the existing load-bearing beams was carried out by our structural engineers to accurately measure and record the rivet pattern of the existing connections. Over 1400 individual Perspex templates were manufactured to capture this information. These templates were then used to replicate each connecting section of the bridge to ensure a perfect fit.
The refurbishment programme had to be carried out over a 16 day/night disruptive possession of the railway. This required Millar Callaghan to have a 24-hour around the clock installation team and supervision on site to progress the contract.
When the new steelwork had been fabricated and checked against the templates they were sent to be shot blasted and painted to railway specifications before being delivered to site.
As soon as the disruptive possession was in place, the bridge was stripped of track, sleepers and ballast, exposing the existing structural steelwork below. The existing rivets were removed with a pneumatic chisel to release the beams. The rivet holes were reamed out to ensure alignment of the new bolts through the various thicknesses of steel. A suitable number of packers were installed to help align and level the new steelwork as it was installed on the existing structure. A system of one beam out and one beam in was adopted to remove the risk of unexpected movement within the bridge structure. This process was carried out for the full length of the bridge until all 340 tonnes of new beams had been installed. The original track was re-laid on top of new timbers, ballast & sleepers.
