The new M4 Junction 15 layout will ease congestion and unlock thousands of homes.

A multi-million pound scheme, which will tackle congestion and help unlock thousands of new homes in Swindon, has opened to traffic.

National Highways, the company responsible for England’s motorways and major A-roads, teamed up with Swindon Borough Council, Swindon and Wiltshire Local Enterprise Partnership and developers Persimmon and Redrow to deliver extra lanes at junction 15 of the M4 and improve local road access from the motorway. 

The £17 million project started last June and will improve journey times and reliability for motorists by tackling congestion at both the busy M4 junction and on the A419, particularly at peak times in the area. 

Mark Fox, South West Head of Scheme Delivery for National Highways, said: “Our roads are vital and these improvements at junction 15 of the M4 will ultimately improve journeys and unlock local economic growth. 

“I’m so pleased that we are able to open this new junction in time for Christmas and can’t wait to see the benefits it will bring to people living and working in the area.

“The improvements to traffic should be immediate, but the benefits will continue for decades as the new junction encourages investment in the area.

“Despite the winter weather and Covid restrictions, we made great progress on the scheme and were able to open it on time and on budget, easing congestion for thousands of road users and the local community.”

The M4 Junction 15 programme included: 

  • Widening of the southbound carriageway between Commonhead roundabout and M4 Junction 15, providing a dedicated left lane for London-bound traffic
  • Widening of the M4 Junction 15 northbound exit to the A419
  • Improving the A346/Marlborough Road entry slip
  • Widening of the M4 Junction 15 eastbound exit-slip
  • M4 Junction 15 westbound exit-slip road, lengthening of the 3-lane section.
  • Widening the M4 Junction 15 southbound gyratory
  • Upgrade of existing footpaths

National Highways engineers came up with an ingenious solution that saved millions of pounds and cut 12 months off the construction time of the scheme.

The use of 29 pre-cast concrete pieces acted as both bridge supports and eventually a subway at M4 Junction 15. The solution avoided the need to demolish a bridge on the A419, approaching the junction from the north, with work progressing while the road remained open above.

For the scheme, National Highways invested £5 million from its Growth and Housing Fund, which supports economic growth, facilitate employment opportunities and enable housing development across the country.

This was jointly funded by Swindon Borough Council (£4.8m), SWLEP (£3m) and Persimmon and Redrow (£4.35m). 

The upgrade follows the start of two major Swindon Borough Council schemes – the Wichelstowe underpass project further west near junction 16 of the M4, and improvement work at the White Hart junction, a vital link between the A419 and A420. 

Swindon Borough Council’s £4.8m investment will complement more than £72.5m in road improvements at the nearby New Eastern Villages development. 

Councillor Gary Sumner, Swindon Borough Council’s Cabinet Member for Strategic Infrastructure, Transport and Planning, said:

“Improving junction 15 of the M4 has always been a strategic priority for the Council in order to relieve the frequent peak rush-hour bottlenecks and create a quick, easy route onto the motorway.

“I am incredibly pleased the work has now finished as it will bring enormous benefits to our local residents here in Swindon and motorists who use the A419 corridor.

“It is also great news for businesses and our local economy as it enhances our first-class transport links and makes us an even more attractive place for firms looking to relocate here.”

Paddy Bradley CEO, Swindon and Wiltshire Local Enterprise Partnership said:

"These works will help safeguard the growth of local Swindon businesses and the wider region for years to come. Reductions in journey times and less congestion will benefit local residents, businesses and visitors to this area.

“Inevitably, construction work at a vital junction causes temporary disruption and so I’d like to thank the motorists, drivers and passengers, for their patience whilst this vital improvement scheme was completed.”

National Highways’ Growth and Housing Fund has been used to match-fund infrastructure projects to unlock developments around the country. 

The company has approved contributions to 28 projects at a total cost of £94.8 million. This investment has in turn attracted up to £129 million in other public contributions and £102 million in private match funding and is anticipated to deliver up to 1.74 million square metres of commercial floor space, 44,000 homes and 45,000 jobs over the lifetime of the developments. 

To date the specialist fund has made huge improvements and brought benefits to local communities, unlocking homes and jobs in Exeter and Taunton elsewhere in the South West, as well as Darlington, Harrogate, Scunthorpe, Grantham, Warrington, Derby, Oldham, Northampton, Durham, Daventry, Leicester and Southampton. 

National Highways is also refurbishing the Broome Manor Lane overbridge which crosses the M4 between junctions 15 and 16.

The scheme involves a full bridge deck refurbishment which includes significant concrete repairs, replacement joints, re-waterproofing and resurfacing, with works set to be completed later this month.