Underbridge, Pontypridd (United Kingdom)

Bilfinger Berger was awarded a contract in June 1992 for the construction of two major advanced railway structures as part of the Pontypridd Inner Relief Road. The first, a long retaining wall formed from bored cast-in-situ concrete piles, required close liaison with the railway operator due to the proximity of the piling rig to the tracks. The second structure was a bridge under the railway, located at a point where the tracks divided, and this was constructed by jacking a pre-formed reinforced concrete box under the live tracks using a patented method developed by Bilfinger Berger in Germany. As the clearance between the top surface of the box and the rails was only 1.1 m, it was necessary to support the track, switches and signal rods on a temporary steel grillage. The box, weighing 3,600 t, was advanced by two sets of jacks capable of a total thrust of 40,000 KN.