Summit Tunnel
The Summit Tunnel in England is one of the oldest railway tunnels in the world: it was built between 1838 and 1841 by the Manchester and Leeds Railway beneath the Pennines. The tunnel is located between Littleborough and Walsden (near Todmorden) and created a vital gateway between Manchester and Leeds.

Engineering
The tunnel is just over 1.6 miles (2.6 km) long and carries two standard-gauge tracks in a single tube, which is shaped like a horseshoe approximately 7.2 m wide and 6.6 m high. The tunnel was mined by hand through shale, coal and sandstone, then lined with six courses of bricks (using over 23 million bricks in all) to form the horseshoe shape. It was aligned by drilling fourteen vertical shafts to provide survey points on the hillside above: after the tunnel was completed two shafts were closed and the remaining twelve were used as blast relief shafts to vent steam from the locomotives that passed through. When completed in 1841, it was the longest railway tunnel in the world.

Recent years
Despite its age, the tunnel has been continuously used for passengers and goods since it opened, with one exception: it closed for the first eight months of 1985 following a very serious fire. The build up of heat in the surrounding ground led to the phenomenon of a 'false spring'. Many plants were seen to be producing flowers and buds as the warm soil triggered a period of new growth. Large portions of the tunnel have been lined with concrete. The tunnel is track circuited with 'reed' type track circuits.

Sources
  • Duncan, S. D. and Wilson, W., Summit tunnel—post fire remedial works, 5th international symposium (Tunnelling '88), Institution of Mining and Metallurgy, 18–21 April 1988; ISBN 1-870706-01-3