The huge new twin 320m UK bridges over a major motorway

A twin bridge is being placed across a major UK motorway. Engineers working for the HS2 project reopened the M6 ahead of schedule after sliding part of the huge new viaduct across the M6. The next phase of the operation is due to take place later this year. The 229.8m long east deck was moved into position during a planned closure of the northbound and southbound carriageways near Birmingham Airport at the end of last month.

Officials say that experts used a "fully restrained" sliding technique for the first time on this project in the West Midlands, allowing the viaduct to launch over the M6 Junction 4 slip road, while maintaining traffic on the carriageway below. This new method was introduced in collaboration with National Highways, in an effort to reduce the time of the operation and "further minimise the impact on road users".

The twin structures, which are being constructed in phases, will ultimately carry HS2 trains over the motorway between London and Birmingham.

An identical west deck is due to be pushed into position next year, bosses say.

HS2 added: "This was the second phase of the operation, following a successful first phase in June this year.

"Beginning on Friday, September 26, the team worked tirelessly to complete the slide and reopen the road from 12.30pm on Sunday, September 28, nine and a half hours ahead of the schedule."

Caroline Warrington, HS2 Ltd's Head of Delivery, said: "This is a major feat of engineering over a vital section of the UK's transport infrastructure, so to be able to reopen the road early is a fantastic achievement.

"These viaducts will be pivotal to the HS2 network, carrying high-speed trains over the M6 and creating better journeys for people for many years to come."

It was initially estimated in 2009 that the high-speed railway project would cost £37.5 billion as a whole, in 2009 prices.

But the expected cost has since increased hugely.

The Government reported in July that, as of the end of April 2025, £40.5 billion had been spent on the programme.

The Transport Secretary, Heidi Alexander, said at the time: "There have been repeated changes in policy, scope and funding and excessive costs incurred in achieving environmental and planning compliance.

"This means delayed benefits and cost increases incurred on HS2 have diverted billions of pounds from other vital transport priorities.

"This is unacceptable; the cycle of cost increases and delays must be broken, and I am determined to achieve this."