M4 Smart Motorway

Going from London to Wales, the M4 forms part of the strategic road network in the west of England. It connects people, communities and businesses, carrying on average 130,000 vehicles per day.

Our Balfour Beatty VINCI joint venture is working on behalf of National Highways to upgrade the road to a Smart Motorway between Junction 3 at Hayes and Junction 12 at Theale. The project, the largest of the Smart Motorway schemes and a flagship project for National Highways, will help alleviate congestion through widening the carriageway and replacing 11 bridges to accommodate a new lane where there is no existing hard shoulder.

More reliable journey times    

Once complete, the Smart Motorway will help reduce congestion along this key road by smoothing the flow of traffic and improving the reliability of journey times. With more reliable journey times and additional capacity created, the scheme will help to support and facilitate economic growth within the region.

Smart working reduces disruption

Seven of the 11 new bridges will be built alongside the existing structures which will then be demolished. 

This approach minimises disruption as the existing bridges can remain in use whilst the new structures are built. It also minimises the length of time the road will be closed to traffic as the majority of works do not require road closures.

Digital innovation enables smooth delivery

We’re utilising digital rehearsals to pre-plan the delivery of works to ensure everything goes to plan on site. This involves building a 4D digital model of what is going to be built and maintained, allowing any potential issues to be identified early on and solved before work begins on site. 

32 miles

of new Smart Motorway


new bridges

The digital rehearsal is also used to train operatives by simulating construction processes in a controlled environment - improving understanding of what is being delivered before work starts.

Data driven decision making

There’s also a Control Centre on-site that allows the team to track the progress of the project and manage resources. All the digital systems and real-time project data is available within the Control Centre, allowing the site team to quickly make decisions to ensure efficient delivery of works.

Additional road enhancements

It is estimated that additional capacity, in each direction, will accommodate for 1,500 vehicles per hour with 38 high visibility emergency areas available. As well as 131 new gantries being installed, there will also be 17-miles of new, upgraded or repaired environmental barriers.