Obstacle Detection
This technology is also required for the under-development technology of obstacle detection at Automatic Half Barrier (AHB) Crossings, the type of crossing which is the most common on our network. Unlike a CCTV crossing, which has full barriers and is overseen by a signaller, an AHB is not monitored and is entirely automatically controlled.
An AHB is operated by the passage of a train over a treadle, which starts the sequence of steady yellow, flashing red, closing barriers (If the treadle fails, an occupied track circuit will start an emergency lowering of the barriers). All this occurs 26 seconds before a train passes over the crossing at permitted line speed (Up to 100mph at an AHB crossing). Why the half barriers? As it is unmonitored, the half barriers allow a trapped driver to escape as only the barrier behind him/her closes, at a full or CCTV crossing, the signaller cannot clear the protecting signal until he/she can see that the crossing is clear.
It is very easy for someone to zig-zag around the barriers, or even to stop deliberately across the tracks (Ufton Nervet?). The DfT has recommended the development of radar obstacle detection equipment as a means of further protecting crossings. While this would be unlikely to bring a train to a complete stand before an occupied crossing (obstacle detection would only work after the barrier closing sequence has completed, giving a maximum of 15 or so seconds of warning to the train driver), it would slow it significantly therefore minimizing any fatalities.
In addition, while a GATSO style camera wouldn't stop these mindless idiots completely, it might deter enough of them to cut down on incidents, and save me from having to attend failures at my local level crossing where some tit has clipped the barrier as it is coming down.
Flashing wig-wag red means STOP! No exceptions! To quote my employer - Don't Run The Risk!
Biting the hand that feeds IT
