Merstham tunnels

Both tunnels were electrified via the installation of a third rail system by the Southern Railway during 1932, after which the route has been largely used by electric traction.

It was bored through chalk, and featured a total of twelve vertical shafts, up which the spoil was raised to the surface in skips by means of horse-drawn winches.

However, this practice was soon abandoned as the large quantities of soot emitted by steam locomotives prevented effective illumination of the tunnel anyway.

[1] Although the tunnel was built by the L&BR, it was located on a section of line between Croydon and Redhill that was to be shared with the South Eastern Railway (SER), when they commenced services on their route to Dover in 1842.

On 16 July 1844, the SER refunded half of the construction cost of the joint line and took ownership of the section between Purley and Redhill, including the Merstham Tunnel.

Shortly after the incident, marks were discovered on the tunnel wall, indicating that Miss Money had been involved in a violent struggle and had been thrown to her death from a moving train.

[8] The sharing of the main line caused a great deal of friction between the SER and the London Brighton and South Coast Railway (LB&SCR), the successor of the L&BR, throughout the 19th century.