The South Devon Railway Company built and operated the railway from Exeter to Plymouth and Torquay in Devon, England. It was a 7 ft 1⁄4 in broad gauge railway built by Isambard Kingdom Brunel, the revolutionary system proved to have insuperable technical difficulties and was abandoned. The line continued as a conventional locomotive railway, the Company promoted a number of branches, through the medium of nominally independent companies. Its original main line between Exeter and Plymouth remains in use today as an important part of the line between London and Plymouth. They chose the route over two suggested longer routes, which were similar to the Teignmouth and Okehampton routes that were actually built later. This ambitious scheme was presented to Parliament as a Bill on 29 February 1840 and its supporters continued to argue in its favour, but the more practical scheme via Newton soon gained favour. The failure of this scheme did not suppress the enthusiasm in Plymouth for a railway, the Great Western Railway and the B&ER were working in close harmony, and were known as the Associated Companies, forming a powerful broad gauge interest in railways. The choice of terminal in Plymouth was a point, for the Three Towns of Plymouth, Devonport and Stonehouse were independent. With Isambard Kingdom Brunel now advising the promoters, a terminal at a location at Eldad was selected. The Companys name was changed to the South Devon Railway and a Parliamentary Bill was submitted in the 1844 session, with little opposition, it obtained its authorising Act on 4 July 1844. Although the route was to follow the coast from Exeter to Newton, from there to Plymouth it would need to run over difficult hilly terrain, and gradients and curvature were challenging. Brunel had planned the route as a double-track locomotive railway, and as late as May 1844 he stated, in reference to the atmospheric system, I have not been called upon to recommend it or not. However Brunel was concerned about the efficiency of steam locomotives. The system is described in the article Atmospheric railway and in the technical section below. Briefly, it involves a pipe laid between the rails, and stationary steam engines located at intervals of a few miles along the line, they exhaust air from the pipe. A piston carriage is placed at the head of each train, the tube is slotted at the top to enable the piston bracket to pass, and a continuous leather seal prevents unwanted admission of air. With a partial vacuum in the pipe ahead of the piston, the leather seal is opened by rollers immediately ahead of the bracket carrying the piston, and closed immediately behind it. In fact the capital outlay would be reduced by £67,000, allowing for the cost of construction of the pumping stations, and annual operating costs would be £8,000 cheaper
Dawlish in the 1870s with the station and atmospheric pumping in the background
1854 map of Plymouth and Devonport, showing the New Passage branch, which was not in fact built.