Freyssinet

The world longest box bridge slide took place over Christmas 2022 to enable the HS2 railway line to cross over the M42 motorway in Warwickshire. In collaboration with Balfour Beatty Vinci (BBV) teams, Freyssinet worked around the clock over the Christmas period to move the 12,600-tonne bridge structure over 163 metres and into position. Freyssinet designed and implemented the sliding mechanism, utilising its Autoripage® technique for heavy handling, which enabled the box to be pushed on a guiding raft and into place. The box bridge slide operation took place between 24 and 26 December. Progressing at four metres per hour, the box was moved into position in under 36 hours, completing well ahead of the programmed schedule. This enabled BBV to proceed with subsequent works and reopen the M42 a day ahead of schedule.

Using Freyssinet's Autoripage® technology, this video shows the 'slide' of a 6000 tonne box structure across a railway, which took place in December 2024. The Radlett Strategic Rail Freight Interchange (SRFI) development involves the construction of a new rail to road freight depot near St Albans. The project requires the design of a new rail connection to the Midlands Main Line (MML), including an embankment to support the new rail chord, and an intersection bridge (underbridge) allowing the new rail chord to pass underneath the four tracks of the MML.

In April 2025, the Freyssinet team successfully installed a 14,750-tonne box structure that will carry the HS2 line beneath the A46 Kenilworth Bypass in Warwickshire. Utilising Freyssinet's Autoripage® technology, the structure - comprising approximately 4,300 cubic metres of concrete and 120 precast beams - was moved 64 metres into position under the existing carriageway. This was accomplished using a guided sliding system powered by hydraulic jacks, supported by 60 kilometres of strand cables and a purpose-built pushing slab. Despite its complexity, the entire box slide was completed in just 9.5 hours - 6.5 hours ahead of schedule.