The scheme, being carried out by Durham County Council, aims to increase capacity at the junction and reduce traffic queues. Widening of the road at this location has been a longstanding aim which is only now possible due to the demolition of the former Thinford Inn.
It will also include the creation of a new junction, which will provide a right turn lane from the A688 and access to a new development due to open later in the year.
Work will begin on Monday, 16 January and is expected to take about three months to complete, during which time the eastbound lane of the A688 will be closed from the roundabout towards Metal Bridge.
Businesses normally accessed via this section of the road will remain open, with parking provided in the layby to the east of the A167 southbound carriageway approaching Thinford roundabout.
The layby will be closed to other traffic while work is ongoing and will remain closed once the scheme is complete.
A diversion will be in place, taking drivers via the A167 to Rushyford, the A689 to the Sands Hall roundabout at Sedgefield and then the A177 to Tursdale.
Several full closures of the A688 will be required towards the end of the works. Further information will be provided in advance of these closures.
Adrian White, Durham County Council’s head of transport and contract services, said: “These essential works will support the regeneration of the area and reduce waiting traffic at what has become something of a bottleneck.
“There will be a diversion in place and motorists should expect some disruption. We would like to thank them in advance for their patience.”
As well as street lighting, signage and drainage works, the scheme will include the diversion of utilities.