Traffic lights, traffic signals, or stoplights – also known as robots in South Africa – are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control the flow of traffic.
A level crossing is an intersection where a railway line crosses a road, path, or airport runway, at the same level, as opposed to the railway line crossing over or under using an overpass or tunnel. The term also applies when a light rail line with separate right-of-way or reserved track crosses a road in the same fashion. Other names include railway level crossing, railway crossing, grade crossing or railroad crossing, road through railroad, criss-cross, train crossing, and RXR (abbreviated).
A railway signal is a visual display device that conveys instructions or provides warning of instructions regarding the driver’s authority to proceed. The driver interprets the signal's indication and acts accordingly. Typically, a signal might inform the driver of the speed at which the train may safely proceed or it may instruct the driver to stop.
Railway signalling (BE), also called railroad signaling (AE), is a system used to control the movement of railway traffic. Trains move on fixed rails, making them uniquely susceptible to collision. This susceptibility is exacerbated by the enormous weight and inertia of a train, which makes it difficult to quickly stop when encountering an obstacle. In the UK, the Regulation of Railways Act 1889 introduced a series of requirements on matters such as the implementation of interlocked block signalling and other safety measures as a direct result of the Armagh rail disaster in that year.
A warning sign is a type of sign which indicates a potential hazard, obstacle, or condition requiring special attention. Some are traffic signs that indicate hazards on roads that may not be readily apparent to a driver.
Wigwag is a nickname for a type of railroad grade crossing signal once common in North America, referring to its pendulum-like motion that signaled the approach of a train. The device is generally credited to Albert Hunt, a mechanical engineer at Southern California's Pacific Electric (PE) interurban streetcar railroad, who invented it in 1909 for safer railroad grade crossings. The term should not be confused with its usage in Britain, where "wigwag" generally refers to alternate flashing lights, such as those found at modern level crossings.
A crossbuck is a traffic sign used to indicate a level railway crossing. It is composed of two slats of wood or metal of equal length, fastened together on a pole in a saltire formation. Crossbucks are sometimes supplemented by electrical warnings of flashing lights, a bell, or a boom barrier that descends to block the road and prevent traffic from crossing the tracks.
The Magnetic Signal Company was an American company based in Los Angeles, California, focused on railway signalling. The company was the manufacturer of the ubiquitous "Magnetic Flagman" wigwag railroad crossing signal, seen all over California and the western states.
Emergency vehicle lighting, also known as simply emergency lighting or emergency lights, is a type of vehicle lighting used to visually announce a vehicle's presence to other road users. A sub-type of emergency vehicle equipment, emergency vehicle lighting is generally used by emergency vehicles and other authorized vehicles in a variety of colors.
Union Switch & Signal was an American company based in Pittsburgh, Pennsylvania, which focused on railway signaling equipment, systems and services. The company was acquired by Ansaldo STS in 1988, operating as a wholly-owned company until January 2009, when US&S was renamed "Ansaldo STS USA" to operate as a subsidiary of Ansaldo in the Americas and Asia.
Traffic signal preemption is a system that allows an operator to override the normal operation of traffic lights. The most common use of these systems manipulates traffic signals in the path of an emergency vehicle, halting conflicting traffic and allowing the emergency vehicle right-of-way, thereby reducing response times and enhancing traffic safety. Signal preemption can also be used on tram, light-rail and bus rapid transit systems, to allow public transportation priority access through intersections, and by railroad systems at crossings to prevent collisions.
In traffic engineering, there are regional and national variations in traffic light operation. This may be in the standard traffic light sequence or by the use of special signals.
Mars Lights are signal-safety lights used in the United States and built by Mars Signal Light Company for railroad locomotives and firefighting apparatus. Mars Lights used a variety of means to cause the light to oscillate vertically, horizontally, or both, to catch the attention of motorists and pedestrians.
A HAWK beacon is a traffic control device used to stop road traffic and allow pedestrians to cross safely. It is officially known as a pedestrian hybrid beacon. The purpose of a HAWK beacon is to allow protected pedestrian crossings, stopping vehicular traffic only as needed. The HAWK beacon is a type of traffic control alternative to traffic control signals and/or where an intersection does not meet traffic signal warrants.
The normal function of traffic lights requires more than sight control and coordination to ensure that traffic and pedestrians move as smoothly, and safely as possible. A variety of different control systems are used to accomplish this, ranging from simple clockwork mechanisms to sophisticated computerized control and coordination systems that self-adjust to minimize delay to people using the junction.
Charles Adler Jr. was an American inventor and engineer. He is most known for developing devices meant to improve transportation safety, including sonically actuated traffic lights, colorblind road signals, pedestrian push-buttons, and flashing aircraft lights.
Level crossing signals are the electronic warning devices for road vehicles at railroad level crossings.
There are around 6,000 level crossings in the United Kingdom, of which about 1,500 are public highway crossings. This number is gradually being reduced as the risk of accidents at level crossings is considered high. The director of the UK Railway Inspectorate commented in 2004 that "the use of level crossings contributes the greatest potential for catastrophic risk on the railways." The creation of new level crossings on the national network is banned, with bridges and tunnels being the more favoured options. The cost of making significant reductions, other than by simply closing the crossings, is substantial; some commentators argue that the money could be better spent. Some 5,000 crossings are user-worked crossings or footpaths with very low usage. The removal of crossings can improve train performance and lower accident rates, as some crossings have low rail speed limits enforced on them to protect road users. In fact, between 1845 and 1933, there was a 4 miles per hour (6.4 km/h) speed limit on level crossings of turnpike roads adjacent to stations for lines whose authorising act of Parliament had been consolidated in the Railways Clauses Consolidation Act 1845 although this limit was at least sometimes disregarded.
Designs of level crossings, where railway lines cross roads or other paths, vary country-to-country.
There are over 3,000 level crossings in New Zealand, with about 1330 being publicly maintained by KiwiRail as of 2013. Of these, 275 crossings were protected by flashing red lights, bells, and half-arm barriers; and 421 are protected by flashing red lights and bells only. The remainder are controlled by "Stop and Give Way" signs. Level crossings are the responsibility of rail infrastructure owner KiwiRail Network, the NZ Transport Agency, and if the crossing is on a local road, the local city or district council. Much like Australia, New Zealand employs American-made crossing warning equipment. There were also in 2013 some 110 stand-alone public pedestrian level crossings; and some private level crossings, which are the responsibility of the land owner.
