Work began on 10 miles section between the M25 and Luton (Junctions 6a and 10) in 2006 and opened in 2009, which included the construction of new parallel roads between Junctions 7 and 8 for local traffic, together with the widening or replacement of eleven underbridges on one or both carriageways, and replacing seven overbridges at a cost of £294 million.