A railway roundhouse is a building with a circular or semicircular shape used by railways for servicing and storing locomotives. Traditionally, though not always the case today, these buildings surrounded or were adjacent to a turntable.
Overview
Early steam locomotives normally traveled forwards only. Although reverse operations capabilities were soon built into locomotive mechanisms, the controls were normally optimized for forward travel, and the locomotives often could not operate as well in reverse. Some passenger cars, such as observation cars, were also designed as late as the 1960s for operations in a particular direction. Turntables allowed locomotives or other rolling stock to be turned around for the return journey, and roundhouses, designed to radiate around the turntables, were built to service and store these locomotives.
Most modern diesel and electric locomotives can run equally well in either direction, and many are push-pull trains with control cabs at each end. In addition, railroads often use multiple locomotives to pull trains, and even with locomotives that have distinct front and rear ends, the engines at opposing ends of a locomotive "consist" (a group of locomotives coupled together and controlled as a single unit) can be aligned so they face opposite directions. With such a setup, trains needing to reverse direction can use a technique known as a "run around," in which the engines are uncoupled from the train, pull around it on an adjacent track or siding, and reattach at the other end. The engineer changes operating ends from the original locomotive to the one on the opposite end of the locomotive consist.
Railroad terminals also use features such as balloon loops and wyes (Commonwealth: triangle) to reverse the orientation of railroad equipment. Because of the advent of these practices, modern roundhouses are frequently not round and are simply large buildings used for servicing locomotives. Like much other railroad terminology, however, the structure has retained its traditional name. The alternative term engine-house encompasses both semi-circular and rectangular structures and broadly describes all buildings intended for storage and servicing of locomotives. Shops or workshops are buildings containing hoists and heavy machinery capable of major repairs beyond routine servicing. Some roundhouses include shop facilities internally or in adjoining buildings.
Since the great dieselisation era of the 1940s and 1950s, many roundhouses have been demolished or put to other uses, but a few still stand and remain in use on the railroads. Early roundhouses were too small for later locomotives. The buildings' peculiar shapes can make it challenging to adapt them to new uses, but they can also be visually pleasing.
Purpose
Roundhouses were originally constructed to service steam locomotives. In North America, regular daily serving began with a hostler moving an engine to an ash pit to remove the detritus of burned wood or coal. The locomotive's tender would be refilled with fuel, water, and sand, and the engine would be placed above an inspection pit so that workers could inspect it for any maintenance needs, like wear on its brake shoes and wheels. The engine's many moving parts would also be thoroughly lubricated, although this meant that engines typically required frequent cleanings to remove old lubricating fluid along with dirt and anything else that stuck.
At larger 24-hour North American roundhouses, steam locomotives would often be turned around and made ready for service within a few hours of arrival. However, locomotives with major issues or in need of semi-regular maintenance required additional time. Larger roundhouses were adequately staffed with boilermakers, blacksmiths, and pipefitters so that this work could be accomplished on-site; only the most extensive work, such as major unexpected repairs or scheduled major maintenance, required the transport of locomotives to specialized backshops.
History by country
The location of the first-ever roundhouse is thought to be Birmingham. England, built in 1837.
Australia
Valley Heights roundhouse, west of Sydney, New South Wales, is the oldest surviving roundhouse in Australia, and has been preserved as a railway museum.
Canada
The London Roundhouse Project London, Ontario, Canada, is an extensive renovation of the Michigan Central Railroad steam locomotive repair shop which was built in 1887. It is to become the new home of Ellipsis Digital and Engine SevenFour, a pair of emerging technology companies.