Barrier timings at level crossings

[M7R]

I have a question that has been bugging me for a while now and hopefully some can set me straight,

On level crossings there is a set time at which the barrier should come down, and this I understand is dependent on the type of barrier, location and line speed? So is there anywhere I can find this out? As I am curious a out the timings....

I leave near Attenborough station on the way into Nottingham on the MML, in our village there is a full barrier crossing which some times comes down really early (no train in sight some times) and other times it doesn't come down until the train is ready to leave the station 50m from the crossing...

I seem to recall somewhere the time should be 60 seconds at line speed? Is this correct? Also what about for 1/2 barriers? As the one only a few hundred meets away on the access to the busy nature reserve car park seems to come down really late! (A friend said this is because it is a classed as a industrial estate access road and is down a shorter period of time so as not to impede business - is this correct?)

If anyone can help it would be appreciated,

Cheers

Karl

 

[edwin_m]

Full barriers are interlocked with the signals so for non-stopping trains they ought to be lowered soon enough for the train to run through on greens. For a stopping train they need not be lowered until the train arrives in the station (assuming a signal at the platform end as at Attenborough). The operator may lower the barriers sooner than strictly necessary if for example he needs to do several other things at the same time.

 

[A-driver]

It will depends on if the crossing is automatic or manual. Also depends on e approach speed of the train, if accelerating from a station it may take longer to reach the barriers than if running at line speed etc.

 

[Sidious]

The Sequence for Automatic Half Barriers is:

0:00 Amber
0:03 Flashing Red - Barriers Up
0:07 Barriers begin to fall
0:13 Barriers down
0:28 Minimum time in which train arrives if travelling at line speed.

The first sequence in this video puts the train at the minimum time.

 

[M7R]

Sorry I should have said there is a signal on the platform at Attenborough,

I under stand that pretty much every train which goes through Attenborough isn't traveling at line speed, they are either slowing for beeston, or accelerating out of beeston or slowing as they are catching up with a stopper train running ahead,

I still can't remember though where I read or heard about full barriers being 60 seconds at line speed... Maybe I am wrong on this...

Thanks for the quick replys though, this forum is a welth of knowledge! I have spent the last month reading old posts on rolling stock etc with great interest.

 

[Sidious]

I would imagine that for full barriers the length of time can alter depending on the circumstances.

With Half Barrier, signalling is not an issue, but with full barrier, particularly on a high-speed route (like the ECML) the barriers will have to be dropped and the crossing cleared by the signaller so that all of the signals on the approach will show clear for the train.

I can think of crossings in Nottinghamshire (Claypole, Botany Bay) where the line speed is 125 MPH, and the barriers get dropped about 2 1/2 minutes before the train. This means that the train driver doesn't get a YY signal on approach.

 

[CallySleeper]

The LC at Attenborough is a CCTV crossing. This means it isn't automatic and is controlled by the signalman. Thus, the timing of the crossing in relation to passing trains is at his discretion.

For a train not stopping at the station, this could be two minutes or more prior to the train passing the crossing so that the train has proceed aspects before it and isn't forced to slow down, hence the wait.

For up trains stopping at the station, there is (was in the old Trent PSB anyway) a stopping/not stopping plunger. This was mainly for the automatic LC towards Trent, however it also caused the signal at the crossing to only clear when the train was stationary. Thus, the signalman would only lower the LC when the train was ready to depart.

Hope this all makes sense. In short, Attenborough isn't an automatic crossing which is why the barriers don't come down xx seconds before a train passes.

 

[M7R]

That's brilliant thanks, and does explain why some times you wait ages and other times you don't.

Just out of curiosity then if it is a full automatic barrier is it 60 seconds at line speed? Or a shorer time?

Thanks

 

[A-driver]

When I used to sign the manual crossing at Mitcham eastfields drivers always said that it depended if the signaller had driven to work or got the train as to how long the barriers stayed down. It was quite common even for fast trains to be checked down to a red there whilst waiting for the gates to close. I believe as it was a busy road signallers were instructed to try opening the barriers whenever possible between trains.

 

[jopsuk]

The Granhams Road crossing south of Shelford can be a bad one- at worst, I've waited over five minutes before the first train has turned up.

 

[Llanigraham]

My barriers can be down for up to 7 minutes if there is one in each direction, but generally it is 4 minutes.

EDIT:
This is a set of full barriers on the Marches line.

 

[Tomnick]

(A friend said this is because it is a classed as a industrial estate access road and is down a shorter period of time so as not to impede business - is this correct?)

I think this is the only bit of the original question that's not been answered - it doesn't sound correct! AHBs (as at Barton Lane) have two main benefits generally: reduced waiting times for motorists and reduced operating (supervision) costs for the Railway. They'd not be introduced purely to reduce delays to road traffic at a specific location though - there are (or were?) tight restrictions on where they could be used, based on road layout, traffic levels, line speed and so on, and the main driver for conversion to AHBs - where suitable - would be to reduce operating costs.

Full-barrier crossings can be a challenge sometimes, balancing the need to keep trains running without delay against the queue of frustrated faces at the barriers! It's sometimes difficult, particularly on an Absolute Block line, to know exactly where the approaching train is - we're lucky to have short-ish sections on either side, but I've seen all sorts of methods - from egg-timers to microwave ovens - used elsewhere to get the timings right for a train travelling through a longer section in rear.

 

[55018ballymoss]

As many people have said previously, it depends on whether the level crossing is automatic, or manually controlled by the signaller (either in a crossing box or by CCTV remotely).
In the case of automatic crossings (where there is no station on the approach to the crossing), a train "strikes in" by running over the treadle on the approach to the crossing, which initiates the lowering process at the crossing, and once the train passes over the crossing, the barriers raise.
In the case of manual crossings, it is at the discretion of the signaller. Usually, these crossings are on Absolute Block signalling (rather than Track Circuit Block), which means that the line is not completely track circuited, so the signaller may use a timing system (such as an egg timer!) to give an estimate of when the train "should" be due, as he/she has no other way of seeing where the train actually is!
I know from experience, that this can lead to crossings being down for an extended period of time if the train is delayed or fails in the section approaching the crossing. It is not nice to be delayed at the crossing, and I do sympathsise with the drivers, but I would rather keep them safe...

 

[dk1]

Being CCTV both Manningtree & Ely can be down for a very long time indeed. Signallers try to give a quick lift if possible but especially Ely can cause problems with queuing traffic so to save possible rail delays its easier to make them wait.

 

[12CSVT]

One of the treadles for Floriston level crossing (on the WCML, just north of Carlisle Kingmoor yard) is at Quintinshill, 4 miles away. Whilst this would allow about 2 minutes to activate the crossing for a southbound Pendolino, presumably this could result in the barriers being down for a long time for a slow moving southbound freight.

 

[Tomnick]

Do they have treadles? Track circuits ought to be sufficient for auto-lower at a CCTV crossing, I'd have thought - the worst that should happen is that the train is brought to a stand at the protecting signal. It can be turned off and the sequence started manually if necessary, but it's more likely that there's just a longer delay - after all, you still need to have the barriers down before the slow freight reaches the second signal in rear to avoid delaying it.

 

[edwin_m]

The standard is to have both track circuits and treadles for automatic crossings. This is because if the track circuit fails to operate for a few seconds due to rail head contamination etc, the barrier sequence might not be complete before the train arrives.

 

[Tomnick]

Floriston is a CCTV crossing.