Bletchley Flyover Reconstruction

Over the first weekend in May 2021, ABM’s supply of prestressed beams and precast, reinforced concrete cill beams contributed to the successful achievement of a major milestone in the construction of the East West Rail (EWR) link which will reinstate the rail connection between Cambridge and Oxford.

To the south of Bletchley station EWR crosses over the West Coast Mainline. The existing Bletchley Flyover was built in 1959 and had been largely redundant for the last two decades. To minimise disruption to the busy West Coast Mainline, the new crossing is being made as box using 101 prestressed beams to span the tracks.

Work on production of the beams started in early 2021 and by the end of April all one 101 beams were on site, adjacent to the tracks ready for installation over a weekend blockade of the main line.

The 41 cill beams weighing up to 28 tonnes and the 101 prestressed beams, some over 30m long were successfully installed by the East West Rail Alliance in the available time. To further minimise the amount of on-site casting, the end beams for the roof slab were supplied with a secondary cast-on detail which will act as permanent formwork for the deck pour.

In addition to the precast concrete components, ABM has also supplied its unique Diaphragm Formwork System (DFS) pre-fitted to the prestressed beams to allow the subsequent in-situ concrete works to be carried out without the need for temporary formwork at high levels adjacent to the live railway. The system provides vertical permanent formwork to close the front face of the diaphragm between the prestressed beams.

Over the next few months, ABM will go on to supply prestressed beams, cill beams and Conarch structures for the 9 further spans of the Bletchley Flyover and 7 other bridge structures on the line towards Oxford.