These lines were built as single-track, broad gauge railways by Isambard Kingdom Brunel. They were designed for atmospheric power and although this was only used from 13 September 1847 until 9 September 1848; the remains of several of the South Devon Railway engine houses used for the stationary engines can still be seen by the side of the line. The track was converted to standard gauge on 21 May 1892. Double track was laid in sections over a period of several years, requiring the widening or removal of several tunnels near Teignmouth.