Level crossing signals

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Level crossing signals" – news · newspapers · books · scholar · JSTOR (September 2013) (Learn how and when to remove this message) The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. You may improve this article, discuss the issue on the talk page, or create a new article, as appropriate. (May 2021) (Learn how and when to remove this message) (Learn how and when to remove this message)

Signal device with flashing lights mounted on a cantilever, on the Soo Line in Trout Lake, Michigan, July 2015

GRS signal and barrier on Argentine Belgrano Norte Line, Florida Oeste, July 2012

Level crossing signals are the electronic warning devices for road vehicles at railroad level crossings.

Level crossings can be operated in various ways. In some countries such as the UK, the warning devices are more often than not activated by remote control, I.e. an operator pressing buttons. However, the majority of countries have automated systems.

Automated level crossings are found in most developed nations and vary greatly, but this page in particular is specific to the United States. Such equipment works as follows:

The basic signal consists of flashing red lights, a crossbuck and an alarm (either a bell, speaker that mimics a bell sound or an electronic siren), attached to a mast. At most crossings, the signals will activate about 30 seconds before the train arrives but there are sensors measuring speed so that the crossing knows when to activate; so, the slower the train is, the longer the delay and the faster the train is, the earlier the crossing activates. In some countries (such as the Czech Republic or Slovakia) there is also a flashing white light, which means that it is possible to pass the level crossing at a higher speed than generally allowed.

At many crossings, there will be a barrier (or "gate" in the US) added to the signal, which descend over the road and block entry. The barriers will be fully lowered 15 to 20 seconds before the train arrives (US), and will rise and the signals will shut off once the end of the train clears the island circuit.

Automatic crossings generally have no or half-width barriers to prevent cars and pedestrians becoming trapped on the tracks with no escape, and manually-operated crossings have full-width barriers (either 2 or 4 arms which block the whole road). However, a number of counties automate fully-closed crossings anyway despite the obvious dangers; however, many such crossings are accompanied by obstacle detection sensors to ensure the tracks are clear.

The time interval may be controlled by a level crossing predictor, an electronic device which is connected to the rails of a railroad track, and activates the crossing's warning devices (lights, bells, gates, etc.) at a consistent interval prior to the arrival of a train at a level crossing.^[1]

Crossbucks also may have legends saying, for example: "RAIL ROAD CROSSING" (United States), "RAIL WAY CROSSING" (Australia and New Zealand), "PELIGRO FERROCARRIL" (Latin America, meaning DANGER RAILWAY), or be wordless (Canada and many other countries).^{[citation needed]}

Many states in the US are now requiring the use of this type of equipment at all newly constructed level crossings.^{[citation needed]}