The Teign Valley line was a single-track railway line that ran from Heathfield, Devon, to Exeter via the Teign Valley. It joined the South Devon main line at Exeter City Basin Junction.
The Teign Valley Railway Company was given Royal Assent in 1863 and opened on 9 October 1882, branching from the Moretonhampstead and South Devon Railway's station at Heathfield, to Christow. In 1903 the line was extended to Exeter. It served mineral quarries in the valley and had a passenger service. For a brief time there was an engine shed at Ashton.
The mineral traffic that had provided much of the line's revenues was also its downfall, as the quarries provided roadstone for Devon's expanding and improving road network. In the 1920s and 1930s, the new motor bus services meant that passenger traffic dwindled. The mineral traffic soon followed. Meanwhile, the Great Western Railway placed camp coaches in some of the stations providing holiday accommodation. A small station was opened at Chudleigh Knighton Halt on 9 June 1924.
The line saw a resurgence of traffic during the restrictions and petrol rationing after the Second World War however passenger trains were withdrawn in June 1958. This was five years before the publication of The Reshaping of British Railways which led to the closure of many similar routes. Flooding caused the line to be closed entirely between Christow and Exeter in 1961, following which the gradual withdrawal of freight saw the line finally close in 1967.
The line followed a sinuous course from Heathfield to Exeter, which was the Up direction. From Ashton the line climbs considerably to Longdown, with a long stretch at 1 in 64. From Longdown the line falls at 1 in 58 for several miles.