The runway extension works are currently estimated at £33m and form part of a wider £65m contract to also divert the A45 dual carriageway between Birmingham and Coventry.
The 405m runway extension, which won planning permission in 2009, will give the airport the ability to offer long-haul flights to Asia and the US west coast.
It is due to become operational in Spring 2014 and has been welcomed as the most important transport project in the region since work began on Birmingham’s £600m New Street Gateway.