A20 Road (England)

The A20 is a two-digit major road in south-east England, carrying traffic from London to Dover in Kent. Parts of the route now followed by the modern road, particularly the first section, was opened as a turnpike in the early part of the 18th century. The line of the road throughout Kent runs closely in parallel with the M20 motorway.

Traffic leaving London at first takes the A2 road; at New Cross in the London Borough of Lewisham the A20 turns off and heads in a south-easterly direction, becoming in turn Lewisham Way and Loampit Vale. The latter road forms a large junction, where the A21 leaves for Hastings. The road now runs through Lee High Road into Eltham Road, which in early days took the A20 through Eltham. This junction contains a 41 m yellow box junction. A little over 0.5 miles (0.80 km) along Eltham Road begins the Sidcup Arterial Road, opened in 1923, and which continues as the Sidcup Bypass, crossing the A222 at Frognal Corner and the A224 at Crittall's Corner. At Swanley it flows directly onto the M20 motorway.

Entering Kent, it runs past Swanley and the racing circuit at Brands Hatch before descending steeply from the North Downs escarpment past Wrotham and on to the county town of Maidstone. The route beyond Maidstone travels East, through the villages of Bearsted, Harrietsham, Lenham and Charing to Ashford.

The section between Maidstone and Ashford, was the only link between the two separate sections of the M20 for 10 years, during the 1980s until the 14-mile (23 km) missing link of the motorway was completed in May 1991. Part of the A20 in Ashford formed part of the Ashford By-Pass, a dual carriageway opened in 1957, which used to run from what is now the roundabout with Simone Weil Avenue to the Willesborough roundabout. Simone Weil Avenue, is the original A20 bypass, but has been diverted to curtail at Canterbury Road. The eastern end of the old by-pass is now the M20.

The A292 takes over the former A20 through Ashford itself, but the road soon remerges as it heads through Willesborough and Sellindge in the direction of Hythe. It takes a sharp turn left at Newingreen (the site of the UK's first motel) before entering Folkestone via Cheriton, passing the vehicular entrance to the Channel Tunnel, forming part of the town's original bypass as the trunk road from the M20.

Just before Folkestone the M20 becomes a dual carriageway and enters the roundhill tunnel where it proceeds along the Alkham Valley before crossing over and dropping down into Dover. This part of the A20 was completed in 1993 as a project included in the Parliamentary Bill for the Channel Tunnel. Prior to that the A20 terminated in Folkestone at what is now the A259 Churchill Avenue.

During 2011, structural failures in and around the Roundhill Tunnel have caused the A20 to be closed in this area numerous times.

The route then follows the coastline, tunnelling through the hills and descending to the docks in Dover, where it meets the A2 again coming down from Canterbury.