The value of Balfour Beatty’s contract is £35.36m.
The remaining £34m has been spent on historic development costs, land costs and statutory undertaker’s works, plus an allowance for project and programme risk.
The Highways Agency said that the apparently large non-construction costs were not disproportionate for schemes that require land purchase, that have been in development for some time and have been subject to a public inquiry, as this one has. Plans to dual the A21 between Tonbridge to Pembury have been in development since 2001.
The allowance for risk is approximately 10%, which is also not unusual for a scheme of this type, Highways Agency officials said.
Balfour Beatty will dual a 2.5-mile stretch of the main road between London and Hastings, and carry out with associated junction and road layout improvements. These include two new underpasses and an overbridge.
Advance work is expected to start this autumn with main construction starting in spring 2015.
The A21 upgrade is one of six major road schemes that the Highways Agency is developing for delivery after 2015 and is in addition to the 24 major road projects on England's motorways and major A roads being delivered between 2010 and 2015.
Evidence given at public enquiry last year suggested that journey times will be improved along this section by up to 65% in 2017 and the number of collisions reduced by 60%.
Balfour Beatty managing director for major projects Stephen Tarr said his company “aim[s] to leave a lasting legacy as a thoughtful contractor behind us”.
The Highways Agency has produced a fly-through video of the scheme (below).