50°51′17″N 0°14′19″W / 50.85472°N 0.23861°W
The Southwick Hill Tunnel is a 490-metre twin-bore road tunnel to the north of Southwick, England.
The tunnel was opened in early 1996 as part of the A27 Brighton bypass and carries the road under Southwick Hill. The border between West Sussex and the unitary authority of Brighton and Hove is close to the eastern entrance of the tunnel. Non-motorised traffic (e.g. pedestrians, cyclists) and mopeds under 50 cc are prohibited from using the tunnel, with a warning sign indicating an alternative route.