The northern link project involves construction of a 2.4 km single carriageway road with five associated roundabouts and two main structures, one of which is an overbridge crossing the Midland Mainline Railway.
This will join the A428 to the west of Bedford to the A6 north of the town and allow Henry Boot developer Hallam Land Management to advance plans for a massive housing scheme.
When complete in 2015, work on the 1,200 new homes scheme can get underway.
The completed bypass will also enable a new employment park providing 650 new jobs and a major county park.
The first phase of the bypass between the A421 and the A428 was completed two years ago by Carillion, giving greater accessibility to the area through improved traffic flow and increased efficiency and safety for journeys.
Prequalification documents must be completed by 19 October and can be found at https://www.delta-esourcing.com/delta