Southwick Hill Tunnel

The Southwick Hill Tunnel is a twin-bore tunnel opened in on 18th March 1996, forming the final part of the A27 Brighton and Hove Bypass.

History

It was opened both over-budget and late due to poor weather and difficult ground conditions. The tunnel was built in preference to a cutting due to the area of land above it belonging to the National Trust and a desire to see the hill preserved. Before work commenced extensive archealogical digs were undertaken. Due to the tunnel this section of the A27 has restrictions preventing pedestrians, cyclists, horse-drawn vehicles, invalid carriages and motorcycles under 50cc from using the road. An alternate route using the A293 and A270 is signposted for these vehicles and is also used during the regular weekend evening closures for maintenance.

Structural Form

The tunnel is bored through chalk downland using the New Austrian Tunneling Method, with cut-and-cover at either end for the portals. There are lane control signals in place to allow for two-way running in either tunnel, though these are rarely used.

Diversion

During maintenance, accident or for prohibited vehicles there is a short diversion route that can be taken, this used to have a unique diversion symbol as shown on roads.org.uk as a blue circle and a red diamond, however in 2009 these were replaced with normal diversion symbols.

Links

• Youtube: Opening day news report
• Local newspaper states that the tunnel is the entry point for secret military bunker
• Discussion on above