The firm won the job, as tipped in the Enquirer, with a £129m bid and will upgrade the M3 between Junction 2 on the M25 and Junction 4a to a four-lane motorway by converting the hard shoulder to a permanent running lane.

Electronic signs, operated by a regional control centre, will be installed to manage the flow of traffic in response to driving conditions.

Mobilisation work is due to start at the beginning of August.

Main construction works starts this autumn with completion scheduled for spring 2017.

Construction activity will include installing and refurbishing gantries, new static and variable signs, concrete safety barriers, drainage and surfacing works.

The contract is the latest in a series awarded to Balfour Beatty since the contractor joined through the Highways Agency’s National Major Projects Framework in 2010.

In June 2014, Balfour Beatty was awarded the £184m M60 J8 to M62 J20 smart motorway scheme.

In April 2014 the company’s construction joint venture with Skanska completed upgrading a 12 mile stretch of the M25 to a smart motorway, and in January 2014 Balfour Beatty completed upgrading parts of the M4 and M5 to a smart motorway in a £88 million scheme.

Balfour Beatty Executive Chairman Steve Marshall said: “This award further strengthens our position as one of the UK’s leading contractors for smart motorways and reflects the strength of the relationship we have built with the Highways Agency over the last 20 years.”

The M3 passes through Chobham Common, one of the largest areas of heathland in Surrey, and Balfour Beatty’s sustainable design will take into account ecological considerations with natural habitats reinstated and enhanced.