Summit Tunnel - Definition

The Summit tunnel in England is one of the oldest railway tunnels in the world: it was built between 1838 and 1841 beneath the Yorkshire Dales.

It runs north-south between Todmorden and Littleborough. The tunnel is just over 1.6 miles (2.6 km) long and carries two standard-gauge tracks in a single tube.

The tunnel was mined by hand through clay, then lined with bricks. It was aligned by drilling fourteen vertical shafts to provide survey points on the hillside above: after the tunnel was completed these were used as blast relief shafts to vent steam from locomotives passing through.

Despite its age, the tunnel has been continuously used for passenger and freight since it opened, with one exception: it closed for the first eight months of 1985 following a serious fire. This Summit tunnel fire may have been the biggest underground fire in transportation history.