Part of the A5 will need to be diverted onto a temporary road to make room for the building of the Flore/Weedon bypass it has emerged.
A length of the route will be shifted onto a specially constructed temporary road to allow a new roundabout to be built while keeping the trunk road open to traffic.
Work has already started on the bypass, which will take the A45 north of Weedon and Flore. The new junction with the A5 will be at a new roundabout.
While the A45 is maintained by Northamptonshire County Council, the A5 is deemed of national importance and is run by Highways England. As local motorists also know, the A5 is a major alternative route for when there are problems on the M1 nearby.
Details of the precise route of the temporary A5 have not yet been released.
In its first newsletter on the project, Northamptonshire County Council’s highways contractor KierWSP said: “Our priority is keeping accesses open and allowing traffic to continue as it does now wherever possible. There will however be times where we may have to temporarily close roads and divert traffic.
“The A5 must be kept open at all times but, to construct in this area, we will be building a temporary route for the A5.
“This will take several months to complete and there will be a brief period of disruption as we transfer the traffic from the existing road to our new temporary road.”
A spokesman for Northamptonshire County Council told the Daventry Express: “The new A45 Daventry Development Link road will form a roundabout junction with the A5, which is maintained by Highways England and is a major trunk road.
“When the work is complete the A5 will be on the same route as it is now but will be raised up on earthworks by about four metres where it meets the A45.
“While the work is taking place the A5 will be temporarily re-routed to the west over a linear distance of about 500 metres (around 550 yards).
“Because the A5 is a busy major route and the main diversion route for the M1 between junctions 16 and 18, this was the only feasible option.
“The temporary A5 will meet the criteria required for trunk roads set out by Highways England.”