Railway turntable

Turntable on the Sabah State Railway at Papar Station (Sabah, Malaysia)

A small turntable at the Orange Empire Railway Museum in Perris, CA. This type of turntable with the central tower and supporting cables is called a “gallows turntable”

In rail terminology, a railway turntable or wheelhouse is a device for turning railroad rolling stock, usually locomotives, so that they can be moved back in the direction from which they came.^[1] This is especially true in areas where economic considerations 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.^[2]

History

Wagon turntable at the National Slate Museum on 2 ft (610 mm) gauge track

Turnplates at the Park Lane goods station of the Liverpool and Manchester Railway in 1831

Early wagonways were industrial railways, transporting goods - initially bulky and heavy items, particularly mined stone, ores and coal - from one point to another, most often a dockside for loading onto a ship.^[3] These early wagonway engineers initially used just a single point-to-point track, and when in operation were required to either position a truck in an alternate location or move it around other wagonway using equipment, would simply manoeuvre it by hand. Whilst the use of man or horse power limited total train weight, this lack of switching limited the total weight capacity of any loaded wagon combination.^[4]

Resultantly, the first railway switches were in actual fact either wagon turnplates or sliding rails. Turnplates were initially made of two or four piece of wood which replicated the track running through them, and circular in form. They were the diameter of the wagons used on that wagonway, and swung around a central pivot. Loaded wagons could hence be moved onto the turnplate, and then by moving the turnplate through 90 degrees, allowed the loaded wagon to be moved onto another piece of wagonway. Thus, the limit on total loaded wagon movement hence raised to a combination of the strength of the wood used in the turnplates/sliding rails construction, and the support available to it. When iron and later steel replaced stone and wood as the rails, total capacity of a loaded wagon combination rose again.^[3]

However, the problems with turnplates/sliding rails were twofold. Firstly, they were relatively small - often no more than a 1 yard (0.91 m) in length - and thus limited the total wagon length that could be turned. Secondly, their switching capacity could only be accessed when the wagon was both on top of them, but most critically still. With busier wagonways and heavier loads, this limited the total capacity of any wagonway. The railway switch which overcame both of these problems was patented by Charles Fox in 1832.

As steam locomotives replaced horses as the preferred means of power, these became optimised to run forward in one direction, most often for operational ease of the driver/fireman and to provide some weather protection.^[3] This necessity to turn heavy locomotives required an engineering upgrade to the existing turnplate technology. Hence like earlier turnplates, most turntables consisted of a circular pit in which the steel bridge rotated. The bridge was typically supported and balanced by the central pivot, ton reduce the toal load on the central pivot, and balanced to allow easy turning. This was most often achieved by a steel rail running around the floor of the pit that supported the ends of the bridge when, but only when a locomotive entered or exited the bridge. Turntables 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.

The turntable bridge (the part of the turntable that included the tracks and that swivelled to turn the equipment) could span 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.

Roundhouse

A larger turntable in front of a roundhouse, 1909

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.

By country

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.

Great Britain

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. The major manufacturers were Ransomes and Rapier, Ipswich and Cowans Sheldon, Carlisle. The GWR was the railway company that built several tables for its own use; there is little evidence any other companies did so..

India

There is a turntable at the Talaguppa end of the Shimoga-Talaguppa railway.^[5]

In 2012, Mumbai Metro One, the BOT operator of the Mumbai Metro Line 1 announced that it had procured turntables to be used on the Rapid Transit system.^[6]

Sri Lanka

In Sri Lanka, most of turn tables which were used in steam era are still in use and some have been abandoned. Most are situated at the major railway yards like Kandy, Nann Oya, Anuradhapura, Maho, Galoya, Trincomalee, Batticaloa, Polgahawela Jnc, Badulla, Puttulam, and Bandarawela and depots in Dematagoda 2no. and Maradana. All working turn tables in Sri Lanka Railways are operated manually. They are used to turn some of rolling stock and non dual cab locomotives. The turntable at Pallai has recently been returned to use, and that at Kankasanture, is proposed to be reinstated. However the Talaimannar turntable seems to have been scrapped during the rebel occupation of the area and the turntable pit filled in.

Israel

Israel Railway Museum, Haifa, have a turntable which was made by Metropolitan Carriage, Wagon & Finance Company, Old Park Works, Wednesbury. It was found buried in the grounds of the Israel Defence Forces History Museums, which is on the site of the old Jaffa railway station yard..

Surviving turntables

A small turntable at the Textilmuseum Bocholt

Drivers turning cable car on a turntable at San Francisco

Several working examples remain, many on heritage railways in Great Britain, and also in the United States. Some examples include:

The following are in storage, awaiting installation at UK sites:

• Barry Rly. -– 65’ outer race. Dismantled ( ex Bricklayers Arms 1970s; moved from Mid Hants Rly.)
• South Devon Rly. - Dismantled (ex Hull Botanic Gardens in 2005; built 1955, 60 ft), planning permission to install at Buckfastleigh requested^[7]
• Midland Railway Centre – Swanwick Jnc. – Dismantled - Hand powered, Balanced 60’, (ex Chinley).
• Severn Valley Rly. - Dismantled (ex Bristol Bath Road) Stored at Eardington. Intention is to install at Bridgnorth. 70’;
• East Lancs Rly. – Dismantled (ex Germany) – stored at Buckley Wells
• Dean Forest Rly. - Dismantled (ex Calais Shed, SNCF, ex MLST Loughborough. )
• Quainton – 60’ Dismantled (ex Hitchin GNR) R&R
• Tyseley – stored dismantled – to be installed at Stratford upon Avon - ex Thornaby (new location proposed 2004, not yet under construction, to be installed by Tyseley Locomotive Works Ltd.)
• Swanage Rly. Furzebrook ex Old Oak Common Depot 2011 - BR (WR) 70’ /125T ?E CS 9709/53 in use at Old Oak Common until 2008, used for HST power car turning etc.
• Mallaig, Network Rail – Dismantled, scheme to install the ex Whitchurch table which is stored at Corpach or Fort William.

New build turntable. Hitachi Rail Europe’s rolling stock plant at Newton Aycliffe in County Durham will have a 80 tonne locomotive turntable and a bogie test turntable; to be supplied by Lloyds British Somers Group.

Accidents

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).^[8] 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."^[9]

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.^[10]

Accidents to locomotives sometimes occurred. For example, if the turntable was incorrectly set and a locomotive was accidentally started or failed to stop, it might fall into the turntable pit.^[11][12]

Unusual turntables

A heavy German goods locomotive on the turntable at the German Steam Locomotive Museum, Bavaria. The pivot of this turntable is off-center, which prevents the turntable from rotating a full 360 degrees.

• In one location in France, 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.
• 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.^[13] 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.^[14]
• The last remaining 3-gauge turntable in the world, used to station trains into the 23 bay roundhouse, exists at the Steamtown Heritage Centre in Peterborough, South Australia.^[15]

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 1980/1990s)
• Valladolid (41°38′25″N 4°43′45″W / 41.6403°N 4.7292°W / 41.6403; -4.7292) – 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 or sector table 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.

References

Wikimedia Commons has media related to Rail transport turntables.