Jackson has successfully completed the project to replace the six original Maurer Multi Element Expansion joints on the QEII Bridge at Dartford.
This project, which was recently recognised as the 'Most Innovative Highway Authority Scheme of the Year' at the Highways Magazine Excellence Awards, has been a triumph for Jackson, as the bridge carries 160,000 vehicles per day and is one of the busiest sections of road in the world. In order to keep the traffic flowing, the team had to devise a method for doing the work whilst keeping the bridge open.
The method was a bespoke designed and built temporary expansion joint, which could be installed during a single night closure over the existing joint. The modular ramp system comprised of 1.2 metre wide units which could be dropped into place. Their built in finger joints allowed the bridge road surface to expand and contract normally and the design of the ramp allowed for vehicles to travel safely at speeds of up to 70mph, well in excess of the limit on the bridge and negating the need for vehicles to slow down. Once in place, work to remove the old joint could be carried out from the underside of the bridge.
Once the old joint had been removed, the new joint was installed, again, during a single night closure. This process involved removing the temporary joint, craning in the new, and then replacing the temporary joint in order to re-open the bridge to live traffic the next morning. Each joint is 19.2m long and spans all four lanes of traffic.
Over the past 18 months the team has worked their way across the bridge, north to south, removing and replacing all six joints. During this time, they've worked 280 night shifts, and removed just under 100m3 of concrete, all of which had to be placed in 20kg buckets and removed from the bridge – a total of 11,400 buckets of concrete.
The ramps have been installed in four separate locations across the bridge, and whilst in situ, 30.2 million vehicles have driven over them. The combined movement of all the joints on the bridge is 33.7mm per °C, with a total range of movement from the hottest day to the coldest of just over 3 metres.