Barrier down times at crossings

[BoroAndy]

What is the thought behind the time a barrier descends to when the train crosses. At a certain town 'X', the full barriers are down for over a minute before the passenger train trundles in or out of the adjacent station. For years local residents complain about the whole town jammed up by gridlocked cars due to the barriers. Nearby is an A road with half barriers, barrier down, 15 secs, train passes at speed, I. E. Much more dangerous.

 

[Tomnick]

Automatic half barrier crossings are no good where there's a significant risk of traffic queueing over the crossing, because they're not proved clear before a train is allowed to approach (which is why they can have such short closure times).

 

[GB]

AHBs are also no good if there is high footfall (ie on or near a high street) or near certain risks such as schools.

 

[Llanigraham]

Just read this thread to see the potential problems:

Traffic jam tailing back over AHB crossing

[AHB = Automatic half barrier] This is not hypothetical, I saw it for real yesterday along Findern Lane in south Derbyshire, where the traffic queuing to get into Mercia Marina for the illuminated drone display was tailing back over the crossing all the way to the Canal Bridge junction in...

www.railforums.co.uk

 

[Watershed]

What is the thought behind the time a barrier descends to when the train crosses. At a certain town 'X', the full barriers are down for over a minute before the passenger train trundles in or out of the adjacent station. For years local residents complain about the whole town jammed up by gridlocked cars due to the barriers. Nearby is an A road with half barriers, barrier down, 15 secs, train passes at speed, I. E. Much more dangerous.

It's mostly down to the kind of level crossing and the proximity of any station.

Where a crossing has automatic half barriers (AHB), trains can receive a green aspect before the crossing has even started its sequence. This is because anyone stuck on the crossing should be able to easily 'escape' if they cross too slowly/late, by nature of the half barriers. Therefore the barrier down time can be very low, as the crossing is purely lowered by the approach of the train, such that the amber light illuminates at least 27 seconds before the train passes.

Where a crossing has full barriers, it must (normally?) be interlocked with the signals. This is to prevent the possibility of someone being stuck on the crossing between two locked gates, with one or more approaching trains being unable to stop. Therefore the crossing needs to be lowered with the train much further away (at least the braking distance, which can be more than a mile on high speed lines) for the train to receive green signals.

This is further complicated where there is a station near the crossing, as there is fine line to be trodden between not unnecessarily slowing down the train on approach to the station and keeping the crossing closure as short as possible.

Unfortunately, whilst better for road traffic, AHBs are much greater safety risk in most circumstances, and will rarely be acceptable in busy town centres.

 

[BoroAndy]

Cheers, but I was not suggesting AHB should be put in a town, just that the full barrier time appeared excessively long.

 

[Watershed]

Cheers, but I was not suggesting AHB should be put in a town, just that the full barrier time appeared excessively long.

Unfortunately that's the problem with having busy crossings near stations. There's just no ideal solution apart from building a bridge/underpass, which is expensive if not impossible in most places.

 

[Tomnick]

Cheers, but I was not suggesting AHB should be put in a town, just that the full barrier time appeared excessively long.

A minute or so isn't long at all really, considering that the barriers need to be down and crossing proved clear before the signals can be cleared for a train - in most cases, that means at least three or four minutes to avoid the train being slowed down (and thus delayed) by restrictive signal aspects on the approach.

 

[55002]

What is the thought behind the time a barrier descends to when the train crosses. At a certain town 'X', the full barriers are down for over a minute before the passenger train trundles in or out of the adjacent station. For years local residents complain about the whole town jammed up by gridlocked cars due to the barriers. Nearby is an A road with half barriers, barrier down, 15 secs, train passes at speed, I. E. Much more dangerous.

Newark Castle is like that since they handed control, from local box to Derby. Barriers are down for ages and the traffic backs up quickly. There was an ambulance stuck there at the crossing last Monday on blue lights waiting for a late Lincoln train. There is bit of furore there about moving the towns police station next to the Castle station which would mean in an emergency the police could be stuck wrong side of the barriers

 

[Annetts key]

What is the thought behind the time a barrier descends to when the train crosses. At a certain town 'X', the full barriers are down for over a minute before the passenger train trundles in or out of the adjacent station. For years local residents complain about the whole town jammed up by gridlocked cars due to the barriers. Nearby is an A road with half barriers, barrier down, 15 secs, train passes at speed, I. E. Much more dangerous.

As others have indicated, the down time of barriers for a full barrier crossing is a lot longer than for barriers on a automatic half barrier crossing.
How long the barriers are down for on a full barrier crossing depends on a number of factors.
These include:

• The type of crossing (controlled by a local signal box or local crossing keepers box, or remotely from a signal box or signalling centre and monitored via CCTV, or train crew operated),
• The line speed,
• The type of signalling,
• The distance the protecting signal is away from the crossing,
• How busy the signaller or crossing keeper is,
• The number of lines and trains if there is more than one train in the area.
• The design of the crossing and it's control circuitry,
• The design and positioning of the track circuits or axle counters, over the crossing and either side of the crossing,
• The location/position of any nearby stations,
• The location/position of any nearby railway junctions including loops.
• And finally, the actual speed of the train(s).

The basic principle for controlled/manual full barrier crossings controlled by a signaller or crossing keeper are:

• The signaller/crossing keeper will start the lowering sequence when they become aware that they have a train approaching. By approaching, this could be miles away. The railway will want the crossing sequence to have completed including electrically proving that all the barriers are fully down so that the protecting signal can be cleared to a proceed aspect (ideally a green aspect if the signal controls allow it). Plus the previous signal(s) to also be able to clear to green aspects. Hence the train will not have to slow down and be delayed.
• If the signaller/crossing keeper has other things to attend to, they are likely to start the lowering sequence earlier than needed, so they have time to do other things.
• The signaller/crossing keeper may not be able to start the lowering sequence when they want to if traffic or pedestrians are crossing, hence they allow some extra time for the crossing to become clear, hence the crossing may be closed slightly earlier than actually needed.
• After the train has cleared the crossing, the signaller/crossing keeper has to wait for the train to clear the relevant track circuit or axle counter section. If there is no auto-raise facility, or this feature is switched off, the barriers will not raise until the raise button is pressed. If there is an auto-raise facility and it is switched on, then the signalling system will raise the barriers without the signaller or crossing keeper needing to do it.

However, the other variables/factors I listed earlier may change things.

 

[Eyersey468]

There is no happy medium at Goole crossing, either the barrier goes down several minutes before the train arrives which causes the town to grind to a halt, or it goes down about half a minute before.