HS2 engineers have lifted the last of six enormous viaduct spans that will carry high speed trains over the M42 in the West Midlands.

The complex multi-stage operation at the Water Orton viaduct site was completed in the early hours of Monday 21 September. To take full advantage of the motorway closure, a separate team - three miles to the south – spent the weekend lifting the last beams that will support another major HS2 bridge known as the ‘twin box’.

The 300-metre-long structure near the NEC is formed of two boxes that will support the railway as it passes over the carriageways. This approach has been chosen because of the angle at which the railway must cross the motorway.

The operations at both sites was led by HS2’s West Midlands construction partner, Balfour Beatty VINCI (BBV).

Engineers can now proceed to the final stages of construction – installing the remaining parapets along the sides of the Water Orton viaducts, and the final concrete pours on the twin box ready for railway tracks to be laid.

HS2 is now at the peak of construction, with site teams focused on boosting productivity route wide. This is happening in parallel with chief executive Mark Wild’s comprehensive reset of the project, designed to ensure that the remainder of the work is delivered as efficiently as possible and for the lowest reasonable cost.

The construction programme has been planned across four weekends, spaced across the summer months, with engineers working on all three structures at the same time to reduce the number of closures.

National Highways also conducted its own programme of works while the motorway was closed – including demolition of the Bickenhill Bridge at the northern side of the M42 junction 6 roundabout.

The two Water Orton viaducts form the top of the triangular ‘delta junction’, linking Birmingham with the mainline heading north. They cross the M42, A446, the Birmingham – Peterborough railway line and the River Tame.

The structural design has been carried out by Balfour Beatty VINCI’s Design Joint Venture (DJV), made up of Mott MacDonald and SYSTRA, with WW+P Architects.

Oliver Shore, Project Director for Balfour Beatty VINCI, said: “The twin box and Water Orton Viaducts are three major structures that cross the busy M42 motorway. In just four weekends, we’ve completed the bridging works on each of them, closing the gap over the north and southbound carriageways.

“This was a huge engineering challenge and I’m so proud of the way our teams have responded. Their skill, dedication and hard work throughout the summer means we can move forward to the next exciting phase of our work.”

In the coming days, BBV’s engineers will extend Water Orton 2 by a further 40-metres, closing the final gap above Gilson Road.

There will be a further closure of the M42 from 23-26 October to install the viaduct’s parapets on the sections directly above the motorway. Engineers will also carry out the fourth and final slide of the M6 South Viaduct West deck. The M6 carriageway will stay open during these works - only the M42 North to M6 North connector road will be closed.