Автодорога A21: Лондон – Хейстингс и проблемы движения

Major road in southern England running from London to Hastings

For other roads with the same name see List of A21 roads. The A21 is a trunk road in Southern England, one of several which connect London and various commuter towns to the south coast. It provides a link to Hastings, East Sussex and parts of Kent. Half of the distance covered is over gently undulating terrain, with some hills and bends. Often traffic is slow moving, particularly on weekdays on the short single carriageway stretches; and in summer with holiday traffic. Because of this, people have described the A21 as "a joke" and businesspeople have been reported to "hate coming down the A21". other sections of the road were similarly dealt with later in the century. It is also the location of the first wildlife overbridge in the United Kingdom, near Lamberhurst. The road between the M25 and Hastings is designated a trunk road, and is maintained and managed by National Highways. The A21 is used for the 55 mile (89 km) Maydayrun to Hastings in which motorcyclists ride from south London to the Hastings seafront. It claims to be the largest non organised event in the UK,

The Pembury bypass opened in 1988, followed by the Robertsbridge bypass in 1989.

The Lamberhurst Bypass was opened on 23 March 2005 to a cost of £18 million. The A21 used to have steep inclines into the village and the valley of the River Bewl. Included in the scheme is Britain's first land bridge at Scotney Castle which facilitates safe migration of wild animals over the road. The scheme was constructed by May Gurney who planted 50,000 trees on the new road.

Between 1988 and 2017, the Tonbridge bypass and the Pembury bypass were separated by a 1.7 mile (3 km) section of 7.3m wide single carriageway with no footways or verges. Severe congestion was frequent as this stretch carried an average of 35,000 vehicles each day, significantly higher than its original capacity, and the number of accidents occurring on this road was above the national average. There were proposals to upgrade this section of A21 to a dual carriageway standard following the Pembury bypasses completion, however they were delayed multiple times. In the 2000s, an upgrade scheme was proposed by the Highways Agency, and in 2013 it underwent public enquiry. The scheme layout followed the existing carriageway and involved the construction of a pedestrian and cycle route along its whole length, as well as upgrading the Longfield Road roundabout into a grade separated Roundabout interchange. £92million of government money was made available to the scheme in July 2013. Preparatory works started in September 2014, which involved nine hectares of ancient woodland being removed. Trees and shrubs were relocated to adjacent land and nesting boxes were installed to protect endangered species such as the dormouse. As a result of the widening of the carriageway a number of buildings were demolished, including a Grade 2 listed 18th century barn. Completion of the scheme was delayed in late 2016 after the discovery of asbestos contamination. The improved road opened in September 2017.

The A21 begins in Lewisham, about 5.9 mile (9 km) southeast of the centre of London. Passing through Catford, Bromley and Farnborough, twenty miles (32 km) from the start of the journey, it reaches the Kent border and the open countryside. Shortly afterwards the M25 is reached, with which it multiplexes for about 5 mile (8 km). At this point, the road becomes a trunk road, a distinction it has held since April 1977. The continuation through Kent heads south east for around 26 mile (42 km). This section is mostly a dual carriageway; but there are a few short stretches of single carriageway, resulting in frequent congestion, especially in peak periods. Beyond the East Sussex border, the road is entirely single carriageway, sometimes with steep gradients. Another bypass takes the A21 around the narrow road through Salehurst and Robertsbridge. Immediately before Hastings is the final hill, almost 4 miles (6 km) in length.

The A21 starts in Lewisham in London at a junction with the A20 known as "Loampit Vale Junction". From there the road uses various roads in Catford, where the A205 (the South Circular Road) crosses the A21; it runs south east up Bromley Hill to enter the London Borough of Bromley, where there are sections of dual carriageway, on the town's gyratory system (part of which is called Kentish Way)
Up Masons Hill the road reaches Bromley Common, the first large scale open space negotiated; briefly, just before Farnborough, the road becomes Hastings Road. The original A21 went through the suburb, the High Street is now the B2158. Until now the road has been in a south easterly direction, but after Green Street Green it turns eastwards towards the valley of the River Darent, and it is at this point that the road pattern makes a complete change from its original route. The A21 originally entered Kent here and climbed to the scarp of the North Downs at Polhill, and then descended through Dunton Green and up the valley of the River Darent to Sevenoaks; through the town centre and then down into the Medway valley via Hildenborough to Tonbridge. The London Road at the north of the town is now the B245; it continued through the long High Street, over the many bridges of the river (during which time it was also part of the A26 from Maidstone ). As the road began to climb out of the valley it took a left fork; shortly after this the route of the modern A21 is rejoined.

Where the new A21 begins, and also where the A224 joins from the north, the road is called the Sevenoaks Road; at Knockholt (Hewitts Roundabout), the road enters Kent near its junction with a spur from the M25 motorway. The A21 actually multiplexes with the M25 and descends the North Downs Scarp here. The M25 then has to use a slip road in the left lane and the A21 takes priority although is still technically a motorway until the junction with the A25 to Sevenoaks and the M26. The oddness of Junction 5 is due to the M26 once being part of the M25. Before the M25 was built, the A21 was the modern A224 near Polhill and then became the dual carriageway Sevenoaks bypass. This section of the road is a grade separated dual carriageway with two lanes in each direction (aside from a three lane section northbound climbing Hubbards Hill). The road passes to the west of the town, running through a nearby valley until it meets the A225 and B245 at Morley's Interchange near Sevenoaks Weald. The next section bypasses the original route of the A21 along the B245 through Hildenborough, Tonbridge High Street, and Pembury Road to join the current route near the second A26 junction. Between Leigh and Haysden the road crosses the River Medway by means of a two span viaduct. Around this point, the road enters the High Weald Area of Outstanding Natural Beauty. The A21 then meets the two junctions with the A26, providing access to Tonbridge and Southborough.

After the end of the Tonbridge bypass, the A21 climbs Castle Hill as the Pembury Bypass as it reaches the North Farm interchange with the flyover for non stop traffic. The next junction is with the A264 road to Tunbridge Wells and the A228 to Maidstone. The road later meets the original alignment at an at grade junction (leaving a brief gap in the central reservation) not long before it meets a double roundabout at Kippings Cross where another section of single carriageway starts. The next section of A21 is a major bottleneck, being a single carriageway with frequent bends. In October 2005 the "Preferred Route" to upgrade this 3 mile (5 km) section was announced. However, the scheme has since been suspended. Safety is a particular concern because a 2002 report stated that a 14 mile (23 km) section of the A21 south of Flimwell was the most dangerous road in the south east outside London, and the 38th most dangerous in the country, however it has since been overtaken by the A259 between Pevensey and Bexhill on Sea.

Plans have been published for a new road between the southern end of the Flimwell bypass and the beginning of the Robertsbridge bypass. The 5.5 mile (8.9 km) improvement will bypass the villages of Flimwell, Hurst Green and Silver Hill. The improvement will commence at the B2079 junction (Lady Oak Lane) on the short section of existing dual carriageway north of Flimwell and terminate at the roundabout at the northern end of the Robertsbridge Bypass. Although part of the road will be brought up to a dual carriageway standard, parts will become a "wide single carriageway". This scheme has been postponed until 2015 at the earliest and currently route protection is being lifted.

Since the Hastings Bexhill Link Road opened, more traffic has started to use the already congested road from the A2100/A28 to the A21 at Baldslow Interchange, Hastings. Construction is underway to build a short link road to the A21 south of the interchange and bring more of the A21, from there up past to a new roundabout in an area north of the interchange, to dual carriageway standard. Another option was to realign the A2100 north of the junction, but this option was less favourable due to environmental concerns.