Coordinates: 53°22′37″N 2°57′58″W / 53.377°N 2.966°W
The Liverpool Overhead Railway Southern Extension Tunnel stretches for half a mile from Herculaneum Dock to Dingle underground railway station, which was the southern terminus of the Liverpool Overhead Railway. The tunnel and station are now disused, the former station now being used as motor repair garage.
The tunnel portal at Herculaneum Dock is half way up a cliff so that the track seamlessly run onto the elevated section of Overhead Railway. The track was electrified using the third rail.