As part of the Crossrail upgrade, a new flyover bridge was launched to ensure a smooth service for the Heathrow Express, by allowing trains to join the Great Western Main Line without delaying, or being delayed, by other trains.
Assembled on the west embankment, the flyover was constructed in two spans which were joined together via temporary works structures for the bridge launch. A nose and tail frame was designed to ballast and to ensure the full range of launch was completed. The launch motive power was achieved with a dual action strand jack. This allowed for both forward and reverse motions via a single strand system which was a contract requirement.
Due to the pre-camber in the structure, the bridge was launched along a curved track from the west embankment, passing over bespoke slide beds designed to pivot and vary in height. Flexible support pads were required to overcome the local stresses anticipated in the bottom chord of the bridge, due to the tolerances within the fabrication of the structure. The launch took place over a fully operational railway line and took just 3 days to complete.