Patcham Interchange

The Patcham Interchange forms the junction of two of the south coast's most important routes, the A27 and the A23.

It was built in the mid-1990s as part of the A27 Brighton and Hove bypass. The design of this junction is somewhat unusual due to the tight geographical constraints within which is resides, as well as the history of the area. It consists of a typical dumbbell above the A27, with a D3 spur heading down to the Mill Road Roundabout on the A23. Additionally there is a free-flow slip from the A27 eastbound to A23 northbound. Heading in the opposite direction (A23 S to A27 W) is also free flow, but via a left hand turn bypass of the two roundabouts. Both these movements also offer lane gains/drops to both roads.

The Mill Road Crossroads pre-dates the junction, providing access to Mill Road and Vale Avenue from the A23 London Road. London Road attracted a number of houses, some of which were demolished by the bypass. Braypool Lane was built to serve the remains of these. The crossroads is now a roundabout, with new link road plugged into it and replacing Vale Avenue.

National Cycle Network route 2 passes through the junction on its western side, it is grade separated from the A27, however does have to cross over Mill Road and the A23 (Single carriageway) when heading southbound.

Strip Maps

Current Layout

History

Pre 1930s

The A23 heads north to south as a single carriageway we a few properties along its course. There is a crossroads, however its only access roads which cross over the A23.

1950s

Slowly there has been development in the near area, the roads that once came through the crossroads are now used to gain access to residential areas to the East and link up to the Dyke Road to the West

1990s

Due to the A27 being rerouted along a new bypass a new junction needed to be constructed to handle traffic coming off and on the A27 to the A23. Due to restrictions with residential areas, terrain, railways and being at the time in an area of outstanding natural beauty (becoming national park in 2010) has resulted in a very odd design. The crossroads has been replaced with a roundabout, however the Eastern arm now takes you to a D3 and not a local residential road. The Western Arm still takes you along Mill Road which runs parallel with the A27, sometimes this is quicker than using normal entry onto the A27 There is still access to local roads by taking the 3rd lane in the D3. Heading southbound down the roundabout there is 3 lanes, becoming 4 just before the roundabout. Leaving the roundabout there are 2 lanes, with a third being added once a slip joins from the A27

Future

The A27 usually is not subjected to queues here, due to the through route being grade separated, however at peak times the D3 link between the A23 and A27 is often congested which results in traffic backing up onto the A23 southbound. Improvements could be made to the dumbbell roundabouts, however free flow slips roads for A23 southbound traffic is needed to fix the issues.

As part of Highways England Expressways plans, the A23 and A27 were highlighted due to their existing motorway alike characteristics. If these roads are going to become expressways then freeflow links would be required between the A23 (to the north) and the A27 in both directions, this is possible but would impact on the national park as well as demolishing some properties.

Routes

Route	To	Notes
A23	London, Crawley, Gatwick Airport
A23	Brighton
A27	Worthing, Hove
A27	Lewes, Newhaven, Universities
		Mill Road 4.1m/13'6" height limit
A2038	Westdean, Hove, Portslade, Shoreham (A27), Chichester (A27)	Mill Road 4.1m/13'6" height limit
NCN20	Pyecombe, Crawley, London	via Mill road
NCN20	Brighton	Along A23

Links

• Roads.org.uk Bad Junctions: A23/A27 Patcham