From Roader's Digest: The SABRE Wiki
|Length:||58.6 miles (94.3 km)|
|Meets:||A20, A205, M25, A25, A26, A28, A259|
|Route outline (key)|
The A21 is the main arterial route out of London for traffic wishing to head to Hastings. Upgraded piecemeal over the years there are still large parts of it that are unimproved and it is nowhere near the quality of the M23/A23 route to nearby Brighton. .
Section 1: Lewisham - Chevening
The A21 begins at a new roundabout with the A20 by Lewisham Station. It trundles down to Catford, where it gets tangled up with the South Circular. This one-way system is called the Catford Gyratory. The road then heads out through the increasingly leafy suburbs, and into Bromley. There's a new bit of dual carriageway spine road which bypasses the High Street - with traffic lights for the A222. This is called Kentish Way though it starts on the cutely named Tweedy Road. The dual carriageway ends at a set of lights with the B228 and the passes through Bromley Common, and the first bit of open space. After a couple of miles it reaches Farnborough Common, and the junction with the A232, called "The Fantail", which dumps traffic from Croydon onto the A21. The terminating A232 passes its primary status onto the A21. Having just come through miles of suburbs, Farnborough itself has a bypass, but is single carriageway. Then the A223 is met at a roundabout.
After another roundabout, the A21 deviates slightly from its original course, and runs north of the railway and Knockholt station rather than south - this is another minute bit of dual carriageway. At the next roundabout, with the A224 the A21 disappears, leading onto a spur of the M25. The spur leads to junction 4 of the M25, where, if traffic wishes to find the A21 again, it needs to head southbound on the main M25 to junction 5 at Chevening. Like the A264 the A21 gets to multiplex with a motorway.
Section 2: Chevening - Pembury
If you are using the M25 to get back onto the A21, as you are directed to do, you have to 'come off' at J5, the Chevening Interchange. Although to access the southbound A21 from the M25 you need only stay on the main carriageway - to continue on the M25 westbound you need to use the slip road as for M25 traffic this is a TOTSO. There's no access to the M26 eastbound. After the junction, the road is still classified as M25 up to the GSJ with the A25. Then it is back to the A21 classification and trunk road status is gained.
The Sevenoaks bypass is unadulterated two-lane grade-separated dual carriageway. There are some good views of the Weald, too. There is a junction with the old A21 - now the A225 and B245 (a rare sighting of a 3-digit 'B' road outside London) - where the Sevenoaks bypass becomes the Tonbridge bypass. The bypass a couple of interestingly shaped junctions with the A26, and multiplexes with it between them. The second of these junctions just about manages to be a trumpet. However, things are about to take a turn for the worse as the `fork' signs appear meaning that the dual carriageway is about to end. From here onwards the upgrades are very much piecemeal. The next section, Castle Hill, is due to be improved on-line from 2011/12 and the Draft Orders have been recently published. It's only a mile or so until you get to another roundabout and dual-carriageway bypass: this time for Pembury. There's a grade-separated junction with the A228/A264, then the bypass stops and chucks you back onto old road at Kipping's Cross.
Section 3: Pembury - Hastings
This section can be a bit painful when traffic's heavy. After a few miles of winding single carriageway, the village of Lamberhurst has now been bypassed with a dual carriageway that panoramically descends and then climbs to pass under a `land bridge' for the Scotney Castle access road, which means that the access road now crosses the A21 on a bridge with trees, etc., on it, the intention being that you don't notice you're crossing a trunk road; from our viewpoint it's an unexpected tunnel. The road passes Bewl Water on single lane dual carriageway (D2 hatched down) and crosses the border into Sussex at Flimwell. There is a traffic light controlled junction in the middle of Flimwell where the A268 and B2087 are met. Now it is a single-carriageway sixteen and a half mile slog to Hastings.
The A229 is met at an uncontrolled junction just north of Hurst Green and this major trunk road now passes through another village, having another uncontrolled junction, this time with the A265. Continuing south, a roundabout is met on the outside of Robertsbridge, which manages to get a bypass, but only a single-carriageway one. After Robertsbridge there is a roundabout with the A2100 which traipses through Battle. The A21 doesn't head this way as it once did and instead forks east to saunter past nowhere in particular on its way to Hastings.
The other end of the A2100 and the A28 are met at another uncontrolled junction on the northern fringe of Hastings. This is about the point where the Hastings bypass would have met, had it ever been built. Instead the road winds its way into ever denser suburbs having roundabouts with the A2101 and A2102 (meaning it meets three roads in numerical order). How the road meets the A259 on Hastings seafront depends on which map you look at, but whichever way you do go it probably doesn't make a whole lot of difference. One version suggests a TOTSO at St. Margaret's Road to an uncontrolled T on the A259, which is probably most fitting at this point.
The A21 originally started on the junction Lewisham High Street and Lee High Road. Today, it starts slightly west of here at a roundabout, running on the Lewisham bypass.
The original route at Farnborough was bypassed in the 1930s - the old route becoming the B2158.
At Knockholt, the A21 diverted south of its current line past the station and down London Road. This was originally a straight through route, but by 1927 the A224 Orpington Bypass joined it by Badger's Mount. It then ran down what's now the A224 to Sevenoaks, then what's now the A225 and B245 to Tonbridge.
Pembury, Lamberhurst and Robertsbridge have all been bypassed.
Plans on the Highways Agency website suggest the whole route down to Robertsbridge will be upgraded to grade-separated dual carriageway. What will happen south of here is unclear.