A four-mile-long contraflow is set to be installed this week ahead of three months of major works to resurface a “bumpy” dual carriageway.

Drivers are warned of disruption for up to 15 weeks along the A299 Thanet Way between Whitstable and Herne Bay following an earlier stint of preparation works last month.

Kent County Council, which is leading the project, will close the carriageway on the Londonbound side between the off-slip from the A299 at Herne Bay to after the Dargate Services from 7pm to 5am starting on Friday and lasting seven nights.

This will allow the contraflow system to put in place on the four-mile stretch between Chestfield Tunnel and Dargate Services from April 15, which will then last for three months.

The coastbound section of road will be dug up during this time and relaid with stronger foundations and multiple layers of asphalt to improve the deteriorating surface.

A combination of hot summers and wet winters has led to ground movements underneath the road surface forcing it to contract and expand, causing undulations in the road on the Chestfield to Whitstable stretch.

The job is expected to cost about £4.4 million and will be completed in July.

Diversions for the contraflow installation between April 5 and April 13 will send vehicles off the Thanet Way and through Herne, Sturry and Canterbury city centre before rejoining at Brenley Corner.

A local diversion route encourages drivers to come off at the Dargate services and head through Yorkletts and Blean towards Canterbury and back to the Thanet Way via Sturry and Herne.

While the contraflow is in place, drivers leaving Whitstable will be able to join the Thanet Way coastbound as normal and join traffic merging from the contraflow shortly before the Chestfield Tunnel.

They will also be able to come off the dual carriageway into the town as normal at the Wraik Hill junction.

Work carried out from March 11 saw the road closed in both directions to upgrade the point where traffic crosses onto the opposite carriageway in the contraflow.

A 40mph speed limit will be in place throughout the works through the contraflow and KCC has warned of lane closures during daytime hours “for the safety of passing traffic”.

While the Londonbound carriageway is closed for the contraflow installation, the coastbound carriageway will remain open both during the daytime and overnight until its full closure on April 15.

Speaking previously, KCC’s cabinet member for highways and transport, Neil Baker, said: “These extensive reconstruction works are essential if we are to continue to keep this road safe, and to minimise future disruption.

“We realise some will be inconvenienced by this planned maintenance, but we have worked hard to come up with a way of doing this that minimises disruption to the travelling public as much as possible.

“Once this essential maintenance is completed we are confident there will be a noticeable difference in the quality of the surface, which I know will be welcomed by all road users.”