HS2’s complex civil engineering programme will shift up a gear this summer, as it prepares to deliver its biggest programme of work yet over the motorway network.
The construction schedule, which starts in June, will see three huge structures built over busy sections of the M42 and M6 in the West Midlands.
In one operation, a twin box will be built above both carriageways of the M42 near Birmingham Business Park – allowing the railway to be constructed over the top. Additionally, two single-track viaducts will be extended over the M42/M6 Toll near Water Orton, and a twin-track viaduct will be installed over the M6 near Chelmsley Wood.
The scale of the engineering works will underline the progress being made on HS2 as viaducts and structures built for the railway – which have been taking shape by the roadside over the last year – start to bridge the carriageway.
HS2 Ltd and its civil engineering partner, Balfour Beatty VINCI (BBV), have spent over a year planning the motorway crossings, in conjunction with National Highways, and every effort has been made to minimise disruption and keep traffic moving.
The six-month schedule was initially planned with nine closures, but the team has synchronised most of the work on the twin box structure and the Water Orton viaducts into the same weekends. This meticulous planning means the total number of motorway closures has reduced from nine down to six.
To minimise impacts on commuters at peak traffic times, junction closures will only take place from 9pm on Friday evenings through to 5am on Monday mornings.
While the schedule of motorway works demonstrates progress is being made, there is still a vast amount of work to do across the 140-mile route between London and Birmingham.
Mark Wild, HS2 Ltd Chief Executive, is leading a comprehensive reset of the project to ensure the remainder of the route is delivered as efficiently as possible and for the lowest reasonable cost. Minimising disruption to communities and working more productively remains a clear priority.
Agnes Usciak, HS2 Ltd’s Senior Project Manager for the works, said:
“The progress we’re making on the viaducts and structures next to the M6 and the M42 is already clear to see, and over the next six months, we’ll start bridging the gaps above the carriageways.
“It’s been a huge team effort to condense this vast programme of work into just six weekend closures, and I’d like to thank all our partners for their co-operation and support.
“Safety will always be our number one priority, which is why we need to divert traffic away from the carriageway while we conduct these vital works.”
The M42 overhead works begin on the evening of Friday, 26th June 2026, with the installation of the roof deck for the twin box. This 300-metre-long structure will allow the high-speed line to be built over the M42. Once complete, vehicles will drive through the box, while trains travel above.
The walls for twin box are being built using a modular construction method, and these works are progressing at pace, without closing the motorway.
The roof deck will be constructed over four weekend closures, allowing engineers to install 175 individual beams, each weighing between 56 and 92-tonnes. The giant beams, which have been manufactured off-site in Leicestershire, will be lifted into place using a 300-tonne crawler crane.
At the same time, engineers in nearby Water Orton are preparing to extend two single-track viaducts that will carry high-speed trains into Birmingham Curzon Street and the rolling stock depot at Washwood Heath.
Already circa 1200 metres long, the team will use a different construction technique to build the remaining 135-metre sections of the Water Orton 1 and 2 viaducts that will bridge the gap between the piers either side of the motorway.
Instead of continuing with the cantilever construction method, the viaducts will be prefabricated in sections adjacent to the carriageway – removing the need for further closures. Once fully assembled, they will be moved into position using self-propelled modular transporters and locked into place above the piers. This significantly reduces the installation time and means engineers can complete the works in just four weekends. This programme of work will commence at 9pm on Friday, 24th July 2026.
The final construction challenge – the installation of the M6 South Viaduct West – requires just one weekend motorway closure, as two stages of the fully restrained slide process will take place over live traffic, eliminating the need to close the carriageway. The single weekend closure will commence at 9pm on Friday, 21st August 2026.
Oliver Shore, Project Director at Balfour Beatty VINCI said:
“We achieved a UK first last year, when we slid a viaduct into place over a live motorway, and we’re delighted to be given the opportunity to repeat the process again this year over the same stretch of the M6.
“Engineering innovations and extensive planning have played a major role in our approach to this vast programme of work, above the M6 and M42, and we’ve made every effort to minimise impacts for motorists and communities.”
As well as being popular commuter routes between Birmingham, Warwickshire and Solihull, the M6 and the M42 transport millions of people to and from Birmingham Airport and the National Exhibition Centre (NEC) for work and leisure.
Over the last five months, HS2 Ltd and BBV have worked closely with Birmingham Airport and the NEC Group to plan for the works, recognising the potential impact this poses to their customers.
In the coming weeks, HS2 and BBV will host a series of community events, in conjunction with National Highways, to ensure residents, businesses, and commuters are aware of the planned closure dates and the approved diversion routes that will be put in place.
Digital toolkits, which include maps and guidance notes, have also been developed to keep businesses, communities and motorists informed.
Ian Doust, National Highways’ Head of Network Planning and Development, said:
"A key priority for us is minimising disruption for those who use our roads so we welcome the measures being taken by HS2 and their partners to reduce the impact of this huge infrastructure project on road users.
“We recognise that there will, inevitably, be some disruption during these weekend closures so we would advise people to leave extra time for journeys and take alternative routes if at all possible.”
HS2 is announcing all the closure dates for the full year to give motorists plenty of time to plan ahead. The first closure will take place in five weeks’ time, on Friday, 26th June 2026.
For more information about the closures and diversion routes, click here or visit www.hs2.org.uk/hs2-motorway-works
