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An atmospheric railway is a Railway in which air Pressure or Vacuum is used to drive Train s. The first commercial application of the system was the line from Kingstown ( Dún Laoghaire ) to Dalkey in Ireland . This system was also used by Brunel in the 19th Century on a 52-mile section of the South Devon Railway between Exeter and Plymouth , England and on the London & Croydon Railway in 1845 , but was soon abandoned. The supposed advantage of the atmospheric system was its Hillclimbing ability, but Brunel chose to test the system on a relatively flat section. Brunel simply assumed that the system would work, because the mainline to Cornwall was designed to contain some very challenging gradients of up to 1 in 38. The atmospheric system did not work, for the following reasons:
BRUNEL'S "ATMOSPHERIC CAPER" The extension of the GWR southward from Exeter towards Plymouth (technically the South Devon Railway (SDR), though supported by the GWR), was one of Brunel's interesting though ultimately unsuccessful technical innovations. Instead of using Locomotive s, the trains were moved by Clegg and Samuda's patent system of atmospheric ( Vacuum ) traction, whereby Piston s sucked air from the tunnel. The section from Exeter to Newton (now Newton Abbot ) was completed on this principle, with pistons spaced every two miles, and trains ran at approximately 20 miles per hour (32 km/h)Dumpleton. ''Brunel's Three Ships'', Intellect Books, 2002. ISBN 1841508004. Fifteen-inch (381 mm) pipes were used on the level portions, and 22-inch (559 mm) pipes were intended for the steeper gradients. Unfortunately, the technology required the use of leather flaps to seal the vacuum pipes. In view of the harsh environment of the line, which runs directly adjacent to the sea and is soaked with salt spray in even moderate winds (to this day, the line cannot be electrified for the same reason), the leather had to be kept supple by the use of Tallow , and tallow is attractive to Rat s; the result was inevitable – the flaps were eaten, and air-powered vacuum service lasted less than a year, from 1847 (experimental services began in September; operationally from February 1848) to September 10 1848 Parkin, Jim. ''Engineering Judgement and Risk'', Thomas Telford (publishers), 2000. ISBN 0727728733. The accounts of the SDR for 1848 suggest that the atmospheric traction cost 3s 1d per mile (£0.10/km) compared to 1s 4d (£0.04/km) for conventional steam power. The pumping station at Starcross , on the estuary of the River Exe , remains as a striking landmark, and a reminder of the atmospheric railway – which is also commemorated in the name of the village Pub . A section of the pipe, without the leather covers, is preserved in Didcot Railway Centre . RECENT APPLICATIONS The Aeromovel ® Corporation markets an automated people mover which is air driven. The light-weight trains ride on an elevated concrete box girder which houses electrical motors that drive air inside the box girder, creating a constant air flow. Each train car has a square plate protruding into the box girder. The plate acts as a sail and can be rotated into the air flow to catch the wind and accelerate the car. Systems have been built in Porto Alegre, Brazil (a two-station demonstration line) and Taman Mini Indonesia Indah, Jakarta, Indonesia (a 2-mile, 6-station loop serving a theme-park). SEE ALSO
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