Level crossings

On Fri, 10 Oct 2003 11:35:04 GMT someone who may be Simon Brooke <[email hidden]> wrote this:-

Quoted message said:

Two possibilities:

(1) People competing for Darwin awards

Highly likely.

Quoted message said:

(2) Faulty lights and/or barriers, which given the state of our failways isn't impossible

If you go to hse.gov.ukhse.gov.ukOpen ↗ and pull down the box for railways you can navigate to an annual
report from the Railway Inspectorate. It is a large Acrobat file, so I have not given the URL. This
contains many things, including a section on level crossings. For another discussion I looked it up.
Of 250 odd faults with barrier equipment 15 were wrong-side failures. By far the majority of the
faults were caused by motorists driving into the equipment. These wrong-side failures mean that some
part of the sequence was not shown to road users, in one case the lights and bells sounded but a
barrier did not fall due to very strong winds, failure of the whole sequence is almost unknown.

In the type of crossing these two deaths were on there are a number of indications in the
controlling signalbox. One of these indicators says whether the electricity supply is healthy
or not. In the latter case the crossing will run on batteries for many hours, but the failure
needs to be sorted out. Should the batteries run flat then the barriers will fall, as they are
held up electrically and fall by gravity. Another of the indicators in the box shows when the
barriers are up.

Note that automatic crossings operate with short cycle times. In places it is possible to see a
train travelling through the countryside without the crossing sequence showing, or to be on a
crossing and see a train in the distance. This can lead to rumours and accusations that the level
crossing is not working, or is working wrongly.

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.

On Thu, 9 Oct 2003 23:13:04 +0100 someone who may be "Pete Biggs"
<[email hidden]> wrote this:-

Quoted message said:

I don't know about the particular ones in this case but sometimes there can be a delay of several
minutes after level crossing barriers have come down with no trains in sight.

Are you talking about the same sort of crossing? The barriers at a full-barrier installation will
be down for several minutes before a train passes. However, that is not the case with an
automatic crossing.

Quoted message said:

better crossings shouldn't be designed where possible.

What do you suggest and who would pay for it? Would the money be better spent elsewhere?

Quoted message said:

Children do stupid things and need to be protected.

So far as is reasonable and practical. However over-protecting children also has dangers, which are
discussed in this group regularly.

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.

On Thu, 09 Oct 2003 17:21:45 +0100 someone who may be JohnB <[email hidden]> wrote this:-

Quoted message said:

Quoted message said:

I saw them - the reports went to great pains to point out that nobody on board the trains was
injured. No [censored], Sherlock.

And they weren't wearing h*lm*ts either (the train passengers that is)

I wonder if either of the cyclists were?

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.

On Fri, 10 Oct 2003 08:52:49 +0100 someone who may be "Succorso" <[email hidden]>
wrote this:-

Quoted message said:

Timings are tricky on automated crossings.

Yes and no.

Quoted message said:

The trigger has to be at a point far enough from the crossing for there to be a safe amount of time
plus a healthy safety margin, for a train travelling at maximum speed for that line.

There is no healthy safety margin on automatic crossings. The only way to have a safety margin is to
interlock the crossing with the signalling system. That is not the case with automatic crossings,
they are a calculated risk. Part of the calculation involves the amounts of traffic on road and
railway, the speed of trains, the number of tracks and so on. The calculation is about right. Nobody
has yet invented a safe railway, but the roads are not safe either.

Quoted message said:

So when a much slower train comes along (for whatever reason) the time delay can seem vast.

If trains using the line operate at a wide speed band then the crossing equipment will delay the
start of the sequence. However there are limits and this cannot be done where trains might
accelerate quickly.

Signals in the vicinity of the crossing can also complicate things and this will sometimes give rise
to the crossing being closed to road traffic for longer than designed.

It could be that the boy was playing chicken.

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.

Succorso said:

Timings are tricky on automated crossings. The trigger has to be at a point far enough from the
crossing for there to be a safe amount of time plus a healthy safety margin, for a train travelling
at maximum speed for that line. So when a much slower train comes along (for whatever reason) the
time delay can seem vast.

IIRC, it's the greater of two miles or two minutes. This can be a bit of a pain locally as there are
several stations all within the space of a few miles.

James

--
"Sorry mate, I didn't see you" is not a satisfactory excuse.

James Hodson said:

IIRC, it's the greater of two miles or two minutes. This can be a bit of a pain locally as there
are several stations all within the space of a few miles.

I think the above post refers to fully gated crossings.

James

--
"Sorry mate, I didn't see you" is not a satisfactory excuse.

On Sat, 11 Oct 2003 15:57:44 +0100 someone who may be James Hodson
<[email hidden]> wrote this:-

Quoted message said:

Quoted message said:

Timings are tricky on automated crossings.

IIRC, it's the greater of two miles or two minutes.

You are thinking of a crossing with full barriers, or gates. With these the sequence will be started
so that the protecting signals can be cleared in time not to delay the train.

At an automatic crossing the sequence is as follows:

1) The amber light shows for 3 seconds.

2) The red lights then flash for 24 seconds.

3) At a half barrier crossing the barriers start to fall 6 seconds after the red lights start to
flash and it takes them 7 seconds to fall (there are bands around the times in this point).

4) Points 1)-3) are accompanied by an audible warning.

5) A train running at line speed passes the crossing.

6) When the train has passed the lights will stop flashing and the barriers will rise. That is
unless the crossing would be open for 10 seconds or less before another train passes. In this
situation the lights continue to flash, any barriers remain down, the "another train coming" sign
flashes at an open crossing and the audible warning changes tone.

As I have said the presence of signals and wide speed bands complicates things. However, equipment
to deal with the latter is getting better and I don't see any hardship in waiting for a bit longer
than the minimum cycle time.

Morons who zig-zag around half-barriers should note that a train may well pass over the crossing 11
seconds after the barriers are fully down. Is it really worth the risk?

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.

On Sat, 11 Oct 2003 18:24:15 +0100 someone who may be David Hansen <[email hidden]>
wrote this:-

Quoted message said:

You are thinking of a crossing with full barriers, or gates. With these the sequence will be
started so that the protecting signals can be cleared in time not to delay the train.

Ooops. I forgot to type that this will be when the train is about two miles from the crossing
(assuming a main line with trains travelling at speed).

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.

On Thu, 9 Oct 2003 18:28:05 +0100 someone who may be "Simon Mason" <[email hidden]>
wrote this:-

Quoted message said:

Anyhow David, what's going on? Here's me sticking up for the poor cyclist and you're defending the
car driving lobby so that they don't get inconvenienced by digging up "their road" for a few
biker's safety.

Nothing in my posting defended the car driving lobby. I simply pointed out that if the problem was
caused by the council then they should be the ones to sort it out.

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.

David Hansen said:

At an automatic crossing the sequence is as follows:

1) The amber light shows for 3 seconds.

2) The red lights then flash for 24 seconds.

3) At a half barrier crossing the barriers start to fall 6 seconds after the red lights start to
flash and it takes them 7 seconds to fall (there are bands around the times in this point).

etc

I can confirm this is correct because my wife was recently concerned about the short time between
the barrier falling and a fast train coming though (about 10s after the barrier is down). The
train company confirmed that the timing met the requirements which were as above. Their point was
that if it were made longer than the statutory minimum, people got impatient with the slow trains
that triggered the barriers at the same track point but took a lot longer to reach the crossing
from there.

Tony

--
"If you tell the truth you don't have to remember anything." Mark Twain

On Mon, 13 Oct 2003 13:53:03 +0100 someone who may be "Tony Raven" <[email hidden]>
wrote this:-

Quoted message said:

my wife was recently concerned about the short time between the barrier falling and a fast train
coming though (about 10s after the barrier is down). The train company confirmed that the timing
met the requirements which were as above. Their point was that if it were made longer than the
statutory minimum, people got impatient with the slow trains that triggered the barriers at the
same track point but took a lot longer to reach the crossing from there.

She should ask Network Rail, via the train operating company if that is who she asked before, about
speed measuring equipment, which will delay the start of the cycle for slow trains. It is fitted in
places and Railtrack was experimenting with a new version of this equipment from the USA. The end
result is that the barriers are down for the minimum time, or not much more, for all trains.

The minimum timing of the original half-barrier crossings was 24 seconds from the red lights
starting to flash to a fast train passing. Following Hixon this was increased to 37 seconds (which
included an amber light phase for the first time), with a 15 second minimum open time. Following a
review in 1978 the timings were reduced to the current 27 second and 10 second minimum open values.
The post-Hixon timings were felt to be too long. These timings have survived the post-Lockington
reviews and are about the right balance.

Such crossings have a good safety record, though there is only so much that can be done for idiots.
Those who think the timings are too short might like to time traffic lights some time.

It is also worth recalling that there are many level crossings which are protected only by some
white lines and a sign. These are road/road level crossings, many of which are on high speed roads
with motor vehicles travelling faster then trains pass level crossings. If the aim is to save lives
then money invested in them is a far better investment than in making road/rail crossings
marginally safer.

--
David Hansen, Edinburgh | PGP email preferred-key number F566DA0E I will always explain revoked
keys, unless the UK government prevents me using the RIP Act 2000.