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Level Crossings
Manually controlled crossings
AHB - Automatic Half Barriers
Other crossings

Level Crossings

Level crossings permit roads to cross rail at the same level. Also called grade crossings in some countries.

Several main types exist according to the needs of a particular location.

Manually controlled crossings

These crossings are interlocked with the signalling. They have gates that are closed, or barriers lowered by the signaller for each train. Signals protecting the crossing will stay red until the crossing is closed and proven clear. Some controlled crossings have control buttons, some have auto-lower and auto-raise facilities that operate when a route is set over the crossing, and some have both.

AHB - Automatic Half Barriers

The barriers lower automatically on the approach of a train without intervention by the signaller.

For signals which are close to the barriers, if the signal would otherwise clear with the train standing at, or approaching, the signal then it will be held at red until the barrier lowering sequence has completed. The crossing has "raised", "working", and "failed" indications to report its status.

Other crossings

ABCL (Automatic Barrier Crossing Locally Monitored) and AOCL (Automatic Open Crossing Locally Monitored) crossings have a white flashing light to tell the driver that the crossing is working correctly, and therefore do not require any control by the signaller.

MWL (Miniature red/green Warning Light) crossings display small red or green lamps to the road or pedestrian user. They do not need signaller intervention.

User Worked Crossings and Occupation Crossings have no connection to the signalling or signalbox, except that some may have telephones to the signaller.

TMO Trainman operated crossings. They are operated by the train driver who has a white light indication if it is lowered.

See also Level Crossings as used in SimSig


Last edited by GeoffM on 15/09/2016 at 03:00