HS2 Completes Installation of East Deck of M6 South Viaduct

HS2 has completed the installation of the East deck of a 4,600-tonne viaduct across the M6 – all without closing the motorway.

The structure was ‘slid’ into place over the course of a 17 hour-long operation consisting of a three-stage process to both assemble and install the 315-metre East deck of the M6 South viaduct.

Once complete, the viaduct will carry high-speed trains heading to Birmingham and the north of England.

A previous phase required a weekend closure of the motorway’s main carriageway, whilst phase installation saw a team led by HS2’s main work contractor Balfour Beatty VINCI (BBV) working closely with National Highways to develop a ‘fully restrained’ process allowing engineers to ‘slide’ the final section into place above moving traffic.

The operation marks the first time such a technique has been used on a UK motorway.

Initially, the process involved an overnight closure of the M6 between Junctions 4 and 5 on Thursday 11 December to shift the viaduct slightly forward by twelve metres, ensuring both ends of the beam were fully supported on concrete piers during this past weekend’s slide procedure.

The viaduct was then pushed across the motorway on Saturday 13 December at a speed of 13 metres per hour, with the procedure necessitating only the closure of the M42 slip.

With the completion of the operation; the M6 South viaduct construction project has officially reached the halfway point. The same process will be repeated in 2026, with a parallel West deck slid into position alongside the first.

Caroline Warrington, HS2 Ltd’s Head of Delivery, said:

Along the HS2 route we are pioneering new approaches to engineering and construction in order to deliver more efficiently and with less impact on our neighbours.

We believe this fully restrained slide was a first for the country, but most importantly it means we’ve been able to cut in half the number of times we’ve had to close the motorway. I’d like to thank everyone who worked so hard to make the operation a success.