HS2 is assembling the west deck of the M6 South viaduct, which high-speed trains will travel across on their way to Birmingham.

Engineers are assembling the deck in four sections. On Saturday, 11 April, workers will slide the first section, which is 107 metres long, over the M6 junction 4 southbound slip road.

Balfour Beatty VINCI, HS2’s West Midlands contractor, believes that it can move the structure, which weighs 1250 tonnes, into place in two days. Engineering teams will use a giant hydraulic jack to pull the viaduct over the concrete piers, and will then lock it into position.

To enable this work to be carried out, the slip road will close to traffic at 5 am on Saturday, 11 April. It is expected to reopen at 10 pm on Monday, 12 April, by which time the viaduct will be in place, and engineers will have completed their safety checks.

The west deck of the viaduct, which is 320 metres long, will be positioned parallel to the east deck, which was put in place last year.

Constructing the west deck needs four stages, one more than the three stages used to install the east deck.

The west deck is made from smaller sections due to constraints on space and because the abutments on which the viaduct rests are staggered. These factors, together with the curve of the loop road, mean that the launching platform – and therefore the sections – had to be shorter than those used to construct the east deck.

Further work on the viaduct will take place over the summer.

“After safely completing the first viaduct on time, our engineers have wasted no time in forging ahead with the second installation.

“Thanks to the world-class engineering techniques we’re adopting on HS2, we’ve once again been able to reduce the number of temporary closures on the motorway while we carry out these essential works.”

Ian Clarke, HS2 Ltd’s project manager for the M6 works