Work is set to start this March on the new scheme, near Gaydon, which aims to cut queuing, boost safety and improve journeys, while unlocking potential economic growth in the area.
Junction 12 is extremely busy, with queues of up to 1.2 miles forming on the M40 southbound hard shoulder during the morning peak.
The Highways Agency scheme, in conjunction with work to create a dual carriageway on the B4451 being undertaken currently by Warwickshire County Council, will greatly add to the capacity of local roads and help support the growing local economy.
Highways Agency project manager Shah Hussain said: “We’ve worked hard with Warwickshire County Council to create complementary schemes to really cut congestion and improve journeys on this busy stretch of the M40.
“Our work will stop drivers queuing on the hard shoulder – which creates an unsafe environment – and will boost the capacity of the junction to cope with growth in the foreseeable future.
“We will now move forward as quickly as possible with Balfour Beatty to deliver this scheme.”
Jonathan Winter, Balfour Beatty managing director for Thames Valley, said: “Our commitment to building sustainably, engaging with local stakeholders, and employing a local supply chain is key to our success, and we aim to leave a lasting legacy as a thoughtful contractor behind us.”
The planned improvements to junction 12 were originally announced by the Chancellor in the 2012 Autumn Statement. The Government has committed £11m to fund the work.