KCC says: It will be necessary to close part of A20 Sandling Road, Postling, near Folkstone, planned from Monday 9 July 2018 for an estimated period of up to 6 weeks.
A20 Sandling Road will be closed between A20 Ashford Road, Sandling and A20 Ashford Road, Saltwood (i.e. between the turnings for Saltwood and Lyminge)
The alternative route suitable for all traffic, fully listed below, is via A20 Ashford Road, Stanford Intersection, A261 Hythe Road / London Road, A259 through Hythe, Seabrook and Sandgate to Folkestone, Earls Avenue and Castle Hill Avenue through to Cheriton to re-join A20 at Cheriton Interchange.
Access to the remainder of the A20 continues from either direction up to where the road is actually closed. Access to Sandling Road, Sandling (i.e. to Saltwood) is from a western direction, and access to Sandling Road, Sandling (i.e. to Lyminge) is from an eastern direction.
There are overnight closures of B2068 Stanford Bypass, currently planned from 19 July for 5 weekday nights. For the duration of these closures, A20 Sandling Road will be re-opened at nights to avoid a diversion clash.
Other than this, the road will need to remain closed outside the working hours.
The full alternative route is via A20 Ashford Road, Stanford Intersection, Ashford Road, A261 Hythe Road, London Road, A259 Military Road (Dymchurch Road and Scanlons Bridge in opposite direction), Red Lion Square, Rampart Road, Prospect Road, East Street, Seabrook Road, Sandgate Esplanade, Sandgate High Street, Sandgate Hill, Sandgate Road, Earls Avenue, Castle Hill Avenue, A2034 / B2064 Cheriton Road, A20 Cheriton Interchange, and Ashford Road.
The closure is part of a project of major cable installation works being carried out by Balfour Beatty, working with Eleclink.
Some delays are to be expected, especially earlier in the evenings / at busier times, so it is recommended that motorists allow extra time for their journeys or consider using alternative routes during these works.
There is a chance that the works may over-run for such reasons as adverse weather conditions or unforeseen engineering difficulties.
The Kent County Council Highway Helpline phone number is 03000 418181
The official Public Notice is here