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A railway turntable is a device for turning railroad rolling stock, usually locomotives, so that they can be moved back in the direction from which they came. This is especially true in areas where economic considerations and/or a lack of sufficient space have served to weigh against the construction of a turnaround wye. In the case of steam locomotives, railroads needed a way to turn the locomotives around for return trips as their controls were often not configured for extended periods of running in reverse and in many locomotives the top speed was lower in reverse motion. In the case of diesel locomotives, though most can be operated in either direction, they are treated as having "front ends" and "rear ends" (often determined by reference to the location of the crew cab). When operated as a single unit, the railway company often prefers, or requires, that a diesel locomotive be run "front end" first. When operated as part of a multiple unit locomotive consist, the locomotives can be arranged so that the consist can be operated "front end first" no matter which direction the consist is pointed. Turntables were also used to turn observation cars so that their windowed lounge ends faced toward the rear of the train.
Most turntables consisted of a circular pit in which the bridge rotated. The outer ends of the bridge were typically supported by a rail running around the floor of the pit, supplementing the central pivot. The turntable bridge (the part of the turntable that included the tracks and that swivelled to turn the equipment) could span anywhere from 6 to 120 feet (1.8 to 36.6 m), depending on the railroad's needs. Larger turntables were installed in the locomotive maintenance facilities for longer locomotives, while short line and narrow gauge railroads typically used smaller turntables as their equipment was smaller. Turntables as small as 6 feet (1.83 m) in diameter have been installed in some industrial facilities where the equipment is small enough to be pushed one at a time by human or horse power. Indeed such small turntables, called turnplates, were common on the early horse-drawn mine railways before the development of the steam locomotive, and were widely used for marshalling wagons and carriages in the goods and passenger stations of the earliest steam railways.
Turntables will have a positive locking mechanism to prevent undesired rotation and to align the bridge rails with the exit track. Rotation of the bridge could be accomplished manually (either by brute force or with a windlass system) by an external power source or by the braking system of the locomotive itself, though this required a locomotive to be on the table for it to be rotated.
In engine maintenance facilities, a turntable was usually surrounded, in part or in whole, by a roundhouse. It was more common for the roundhouse to only cover a portion of the land around a turntable but fully circular roundhouses exist, such as these preserved roundhouses:
- The roundhouse that serves as the basis for the Baltimore and Ohio Railroad Museum in Baltimore, MD
- The Roundhouse in London, England, now an arts centre.
 Turntables in North America
Due to the asymmetric design of many locomotives, turntables still in use are more common in North America than in Europe, where locomotive design favors configurations with a controller cabin on both ends or in the middle. In San Francisco, USA, the Powell cable car line uses turntables at the end of the routes, since the cable cars have operating controls at only one end of the car.
 Turntables in Great Britain
 Vacuum operation
In Britain, where steam hauled trains generally have vacuum operated brakes, it was quite common for turntables to be operated by vacuum motors worked from the locomotive's vacuum ejector or pump via a flexible hose or pipe although a few manually and electrically operated examples exist.
 Turntables in India
 Surviving turntables
Several working examples remain; many on Heritage railways in Great Britain, and also in the United States. Examples include:
- Barrow Hill
- Currie, Minnesota's End O' Line Railroad Park & Museum
- Dallas (McKinney Avenue)
- Fort William(?)
- Guadalajara, Ferromex
- Neville Hill
- NRM York
- Old Oak Common
- Railtown 1897 State Historic Park in Jamestown, California
- Peak Rail, Rowsley South
- San Francisco cable car system
- St Blazey
- Yeovil Junction
||The examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject. (September 2011)|
In the United States, when deciding liability for turntable accidents, most state courts followed the precedent set by the United States Supreme Court in Sioux City & Pacific R.R. v. Stout (1873). In that case, a six-year-old child was playing on the unguarded, unfenced turntable when his friends began turning it. While attempting to get off, his foot became stuck and was crushed. The Court held that although the railroad was not bound by the same duty of care to strangers as it was to its passengers, it would be liable for negligence "if from the evidence given it might justly be inferred by the jury that the defendant, in the construction, location, management, or condition of its machine has omitted that care and attention to prevent the occurrence of accidents which prudent and careful men ordinarily bestow."
In the case of Chicago B. & Q.R. Co. v. Krayenbuhl (1902), a four year old child was playing on an unlocked, unguarded railroad turntable. Other children set the turntable in motion, and it severed the ankle of the young child. The child's family sued the railroad company on a theory of negligence and won at trial. The Nebraska Supreme Court held that the railroad company may have been liable for negligence after considering the "character and location of the premises, the purpose for which they are used, the probability of injury therefrom, the precautions necessary to prevent such injury, and the relations such precautions bear to the beneficial use of the premises." However, the Supreme Court reversed the trial court's decision based on an improper jury instruction as to the evidence.
 Unusual turntables
- In one location in France[specify], lack of space forced the installation of an asymmetric turntable, where the pivot point was about one-third along its length. Such a turntable cannot rotate 360 degrees. A similar, operational turntable is located in Bavaria at the German Steam Locomotive Museum, pictured above.
- At Ventnor railway station, due to lack of space a small turntable was provided to allow steam engines to run around their trains, and similarly at Bembridge railway station.
- There is a turntable for trolleybuses on the Solingen, Germany, trolleybus system, at the former southern end of route 683. The turntable, in German Drehscheibe "Unterburg", was in regular use until November 2009, at which time the route was extended beyond it, but it remains operational and is used for special occasions.
 Multiple turntables
Stations housing large numbers of engines may have more than one turntable:
- – Old Oak Common TMD near Paddington – 4
- Enfield – 3* Broadmeadow – 2
- Linwood – formerly 2 (second removed during 1980/1990's)
- Valladolid ( ) – 2
 See also
- Wye – a way of turning whole trains.
- Transfer table (UK: 'traverser') – provides access to two or more parallel tracks in a space saving manner like a turntable, but without the ability to turn.
- A Sector plate is a traverser that rotates by a small angle.
- Nowadays control cars, or coaches with controls at one end, have largely eliminated the need for turntables.
- Singapore and Hong Kong have a combined traverser-turntable that takes 4-car sets.
|Wikimedia Commons has media related to: Rail transport turntables|
- The Elements of Railroad Engineering, 5th Edition, 1937, William G. Raymond. Published by John Wiley and Sons, New York
- "A trip on the Shimoga Town - Talguppa MG railbus". Irfca.org. Archived from the original on 2007-12-20. Retrieved 2008-02-21.
- Aklekar, Rajendra (16 July 2012). "Metro retro: Forgotten turn-tables back on track". Mumbai. Daily News and Analysis. Retrieved 2012-07-22.
- Epstein, Richard A. (2008). Cases and Materials on Torts (9th ed.). United States of America: Aspen Publishers. p. 589. ISBN 978-0-7355-6923-2.
- Sioux City & Pacific R.R. v. Stout, 84 U.S. 657,661 (1873)
- Chicago, B & Q.R. Co. v. Krayenbuhl, 65 Neb. 889, 91 N.W. 880, (Supreme Court of Nebraska, 1902)"
- Photo of L&N 1250 after it rolled into the turntable pit
- Photo of CSXT 806 with its front truck in the air and rear truck in the turntable pit
- Google Inc. Google Maps – Railway turntable (Map). Cartography by Google, Inc. http://maps.google.com/maps?f=q&source=s_q&hl=fi&geocode=&q=solingen&sll=50.95662,7.145239&sspn=1.283743,2.471924&ie=UTF8&ll=51.137279,7.147213&spn=0.001249,0.002414&t=h&z=19. Retrieved 2011-02-02.
- Trolleybus Magazine No. 290 (March–April 2010), p. 41. National Trolleybus Association (UK). ISSN 0266-7452.