Work began on the South Devon Railway in 1844 and opened in May 1846. Brunel persuaded the Company to adopt the Atmospheric System, which provided traction for the trains with a vacuum tube to draw them along. Pumping Stations were built at 3 mile intervals to create the vacuum in each section. The system was ready in late 1847 but was plagued with problems until it was abandoned a year later and was never used beyond Newton Abbot.

The line was initially Broad Gauge and single track from Dawlish to Teignmouth.
By 1880, broad gauge track was being replaced with standard gauge but SDR did not update their line until May 1892. A third rail was installed along many sections and, over the weekend of 20th May, the work was completed. Many thousand came to watch the work in progress and the gangs welcomed the overtime payments of 25% extra plus 1 shilling a night allowance.

Track through the tunnels remained single track until 1905 when the tunnels were widened to accommodate a second track.

Brunelís viaduct of 1845 had eight stone columns, which restricted the view of the sea, so when, in 1928, plans were put forward to replace it with a steel structure, the local council asked for a new design to open up the view underneath, which is what we have today. The stonework of the old viaduct was strewn over the rocks between Dawlish Warren and Langstone Rock.

Prior to the coming of the railway, the coastline was very irregular and served to break up the tidal action but the sea wall provided a long and continuous run for heavy seas, causing increased scouring of the beach in spite of the several groynes built by the railway authorities. It has been claimed that the beach at Dawlish has been eroded to an average depth of 10 or 12 feet since 1840.