This incident was long before bidi controls came in (on normally unidi lines). My comment about heaters was related to moisture inside a relay case turning to ice which kept the relay up with no power applied.John wrote:Keith wrote:I was told that on one occasion, the chief constable of the area arrived at a certain AHB on one occasion to find the barriers up, no lights flashing, and a train thundering by. There was no collision and no formal report, but ever since then location cases at AHBs have had heaters in them...
Most events are due to local control when the respective parties 'come to a complete misunderstanding' but very rare - wrthat is why bidi controls are mandated!
Keith wrote:I wrote:Barriers at automatic crossings need power to stay upOops!Chris Bellett wrote:ABCL crossings keep the barriers up when the power fails.
That shows how long ago I was working on level crossings - ABCLs hadn't been invented then!
Good point - that is certainly relevant to avoiding the wrong-side failure of the road lights not flashing, even if the related barrier failure is (sort-of) right side.Fay Singpoint wrote:Things may have moved on a bit but we seem to be forgetting that AHB's, ABCL's etc are worked off batteries. You may get a mains power failure (and an alarm to the signaller or lack of DWL to the driver) but the crossing keeps working until the batteries give out.
edwin_m wrote:In an AOCL with remote monitoring as mentioned above, you would presumably alarm the loss of mains supply remotely but would you keep the crossing and driver indicator working normally on battery until the battery charge fell to some critical level?
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