page_title: Glossary of rail transport terms
section_title: S
hierarchical_section_title: Glossary of rail transport terms / S
caption_attribution_description: English: MAGNOLIA signals on the CSX Cumberland Subdivision. Twin B&amp;O Color Position Light bi-directional bracket masts displaying Restricted Proceed and Clear.
context_page_description: Rail terminology is a form of technical terminology. The difference between the American term railroad and the international term railway is the most significant difference in rail terminology. There are also others, due to the parallel development of rail transport systems in different parts of the world.
  Various global terms are presented here; where a term has multiple names, this is indicated. The abbreviation "UIC" refers to standard terms adopted by the International Union of Railways in its official publications and thesaurus.
context_section_description: Saddle tank
  A tank locomotive with the water tank mounted on top of the boiler like a saddle
  Safe place
  An area within the network of an operator where evacuation of passengers can be performed, depending on current operational conditions, with a minimum of risk to the passengers (e.g. stations, refuges on the line)
  Safeworking
  The system of rules and equipment designed to ensure the safe operation of trains
  Sandbox
  A container on locomotives and self-propelled multiple units, or trams, that run on tramways and adhesion railways. The container holds sand, which a crew can drop onto the rail to improve rail adhesion under wet, steep, or slippery rail conditions. The sandbox and operating mechanism are collectively known as sanding gear.
  Sandite
  Consists of a mixture of sand, aluminium, and a unique type of adhesive, used instead of plain sand for extreme slippery rail conditions
  Santa Fe type
  A steam locomotive with a 2-10-2 wheel arrangement, named for the Atchison, Topeka and Santa Fe Railway—the first railroad to use such a configuration
  Saturated locomotive
  A steam locomotive not equipped with a superheater; the steam thus remains at the same temperature as the water in the boiler
  Scale
  Solid debris distilled from boiling water in a steam locomotive. To prevent corrosion damage from scale build-up, the locomotive must undergo a boiler wash once each operating month.
  Schnabel car
  A specialized type of freight car for extra heavy and over sized loads where the car is loaded in such a way that the load forms part of the car superstructure
  Searchlight
  A signal with a single light source usually capable of displaying three different colors. An internal mechanism governs the color displayed.
  Section
  A portion of a train that may be operated independently or combined with other sections to operate as a single unit
  A portion of railway line designated for signalling or maintenance
  An interior portion of a sleeping car made up of two double seats during daytime that convert to two double berths during nighttime
  Semaphore signal
  A type of signal that has a moving arm to change the indication
  Shay locomotive
  A type of geared steam locomotive built to the patents of Ephraim Shay
  Shunt
  In UK and Australian parlance, to make up and divide trains in sidings, to move trains to or from sidings, or to move trains between platforms in a station
  Shoofly
  Temporary track used to avoid an obstacle that blocks movement on the normal track section
  Shuttle train
  A train, usually a passenger service, that runs back and forth, usually over a relatively short distance, such as between a junction station and a branch-line terminus.
  Side tank
  A tank locomotive with water tanks mounted each side of the boiler
  Siding
  A section of track off the main line. Sidings are often used for storing rolling stock or freight. A siding is also used as a form of rail access for warehouses and other businesses, where the siding often meets up with loading docks at rail car height. In the U.S. the term also covers the British term loop. Also, a passing track in the U.S.
  Signal
  A device that indicates the condition of the line ahead to the driver of a train
  Signal box
  A building or room that houses signal levers (usually in a frame), a control panel or a VDU-based control system
  Signal passed at danger
  An event in which a train passes a signal to stop without authorization to do so
  Signalman
  A person in charge of the signalling at a station or junction, often in a signal box
  Slippery rail
  The condition of fallen leaves or other debris lying on and clinging to a railroad track that could cause train wheel slippage, resulting in premature wheel wear and train delays
  Slow order
  A local speed restriction below the track's normal speed limit often designated by yellow and green flags. Slow orders can be imposed on a temporary basis to protect, for example, maintenance of way employees while sections of track are under repair. Widely used in areas where track is substandard and in need of repair.
  Slug
  A locomotive that contains traction motors yet lacks the diesel engine t
caption: A two-head color position signal on a CSXT mainline where the left head displays "Stop" and the right, "Clear"
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