What are railway tunnels and why are they necessary?

What is a railway tunnel?

A railway tunnel is a long artificial passageway constructed below the ground or through an obstacle such as a hill or large building to create a route for a railway line.

Why were tunnels needed?

Railways work best when they are reasonably flat and level. However, the natural land surface of north-west England takes the form of a series of high hills intersected by deep valleys. The surveyors tasked with finding a route for the Settle-Carlisle Railway soon noticed that four major valleys (Ribblesdale, Dentdale, Garsdale and the Eden Valley) could be used for much of route. There is a natural pass connecting Garsdale and the Eden Valley and this provided a usable route between the two valleys at Ais Gill Summit (the highest point on the line). However, there was no easy (naturally occurring) way of passing from Ribblesdale into Dentdale or from Dentdale into Garsdale. Going over the intervening hills was not an option because the ground between the valleys was too high and too steep. Going around the hills was not an option because it would have made the route too long and taken it too close to routes used by competitors. The only option left was to go through the hills, which involved digging and blasting two very long (and very expensive) tunnels, namely Blea Moor Tunnel (2,629 yards long) and Rise Hill Tunnel (1,213 yards long).

In addition to the two major tunnels, there are eleven shorter, tunnels on the Settle-Carlisle Railway and these were constructed to help keep the line reasonably straight (an important consideration for any high-speed railway).

How were tunnels built?

We are very fortunate in having a number of excellent first-hand accounts relating to the construction of the Settle-Carlisle Railway and the following in particular provide vivid accounts of the construction of Blea Moor Tunnel and Rise Hill Tunnel:


Text and photographs by Mark R. Harvey (© Mark R. Harvey, 2017).

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