Light rail terminology
Know Your Rail
- Alignment
- Refers to both horizontal and vertical placement of the tracks within the corridor. The horizontal alignment refers to the location of the railroad as described by curves and tangents, or any straight portion of a railway alignment. The vertical alignment refers to the vertical orientation of the rail. (i.e. below grade, at grade or above grade).
- Catenary
- Overhead wires of a traction electrification system (TES) that contain both messenger overhead catenary system (OCS) from which the contact wire is suspended, and contact wires, OCS. The wire that provides power through direct contact with the pantograph).
Commuter Rail vs. Light Rail
- Commuter rail
- The 40-mile Northstar line that will begin operating from Big Lake to Minneapolis in 2009 on the existing BNSF freight railroad tracks is an example of commuter rail. Commuter rail is an electric or diesel propelled railway for urban passenger service consisting of local short distance travel operating between a central city and adjacent suburbs. Such rail service is generally characterized by usually only one or two stations in the central business district.
- Light rail
- An electric railway system characterized by its ability to operate single or multiple car consists along exclusive rights-of-way at ground level, on aerial structures, in subways or in streets, able to board and discharge passengers at station platforms or at street, track, or car-floor level and is normally powered by overhead electrical wires. The Hiawatha line from the Mall of America to the Minneapolis-St. Paul International Airport to downtown Minneapolis is an example of light rail.
- Consist (pronounced CAHN’-sihst)
- A train consisting of one or more cars.
- Double Track
- A term used to describe the type of track system used on the majority of LRT systems. Each track is separate and carries a light rail vehicle in one direction. When double tracks are used, tracks are usually delineated as:
- Inbound/Outbound
- Northbound/Southbound
- Eastbound/Westbound
- Embedded Track
- Rail that has been embedded in the roadway, street, or walkway.
- Grade Crossing
- A crossing of the track at grade (or street) level over a roadway. Grade crossings are not necessarily protected by automatic warning devices.
- OCS (Overhead Catenary System)
- Also referred to as the overhead (wire). That part of the overhead line equipment consisting of: contact wire, contact wire supports, messenger wires, isolators, counter-weights, hangers and other equipment and assemblies that distributes DC electric power from substations to the light rail vehicle. Also refers to the overhead wire that is under direct suspension that is not Catenary.
- Pantograph
- A device located on top of electric railcars which collects power from an overhead contact wire by means of a sliding contact shoe.
- ROW (Right Of Way)
- The area between and directly adjacent to the tracks. Also refers to dedicated off-street tracks for light rail vehicles. Light rail systems have the ability to control work performed in or adjacent to the ROW.
- Signal bungalows
- Small sheds that hold the equipment to operate and monitor the gate arms and signals at grade crossings as well as the signals that regulate train movement on the alignment.
- Substation
- A building or structure containing rectifiers, breakers and other electrical equipment used to change local utility power into power able to be transmitted to the overhead catenary system and used by the vehicles.
- TES (Traction Electrification System)
- The entire system used to transfer power from the local power utility to the light rail vehicle.
- Yard
- A set of tracks with defined limits for light rail vehicle cleaning, repair, storage or other purposes as designated by the rules and procedures.
(Note: This glossary of terms was compiled from the American Public Transportation Association’s Website, www.apta.com, and from the North American Light Rail Information Website, www.lightrail.net)