Construction of the £124m Heysham Link project will mean closing the M6 in both directions between 10pm and 5am while work is completed on a bridge across the highway.
Drivers have been warned they could face delays as all traffic is diverted off the motorway between junctions 34 (for Lancaster) and 35 (Carnforth) and along the A6 - with high-sided vehicles having to negotiate a B-road to avoid a low bridge.
The work, by Lancashire County Council, is part of the connection to junction 34 which is operated by Highways England.
Project manager Peter Hamer said: “Although Heysham Link is a county council project along the local road network, its connection to the M6 will deliver significant improvements at junction 34 of the motorway with better entry and exit slips – and this work is a vital phase of those improvements.”
This week’s work is on the Foundry Lane overbridge which crosses the M6 between Slyne and Halton.
The bridge is being extended to accommodate new motorway slip roads which will mean the motorway being closed in both directions overnight on Wednesday, Thursday, Friday and possibly Saturday.
During the closures, drivers on the southbound M6 will leave at junction 35 and be diverted along the A6 via Carnforth, Bolton-le-Sands, Slyne, Skerton and Lancaster. They will be guided to re-join the M6 at junction 34.
Northbound traffic on the M6 will leave at junction 34 for Lancaster and will follow the same route in reverse – via Lancaster, Skerton, Slyne, Bolton-le-Sands, and Carnforth.
High-sided vehicles more than 15ft 6in (4.72m) will be diverted onto Kellet Road (B6254) in Carnforth to avoid the low railway bridge on Scotland Road (A6).
The road project, which links the port of Heysham with the motorway network, started in January of last year and is due to be completed next summer.