I don't know the ins and outs of this one - the lorry might have broken down mid-crossing.
In most circumstances being hit by a train in your vehicle is a poor effort.
I treat level crossings like crossing a road, look right and left before proceeding.
Although there is a risk of being rammed from behind as I slow down. :)
www.bbc.co.uk/news/uk-wales-16246123
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On street view it looks like a crossing with automatic half barriers. Systems vary but one might eight expect an interlock between barrier operation and signals and/or sufficient time for a trapped vehicle's driver to call the signaller.
There will almost certainly be an investigation and report by the rail accident investigation guys. Will take several months to produce though.
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>> On street view it looks like a crossing with automatic half barriers. Systems vary but
>> one might eight expect an interlock between barrier operation and signals and/or sufficient time for
>> a trapped vehicle's driver to call the signaller.
There isnt. While staking out the lines in the fens for some shots, I timed some of the half barriers before trains arrived. One was 17 seconds. You dont stop hundreds of tons of train at 50 mph in 17 seconds.
Last edited by: Zero on Mon 19 Dec 11 at 12:13
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Another lorry/lc related one here:
www.raib.gov.uk/publications/investigation_reports/reports_2011/report142011.cfm (incorrect use of 'user operated' crossing)
And published last week:
www.raib.gov.uk/publications/investigation_reports/reports_2011/report202011.cfm
(Train went over crossing while barriers raised)
Last edited by: Bromptonaut on Mon 19 Dec 11 at 12:44
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I never cross one in the act of accelerating and needing engine power to get across. I like to build up a bit of speed first, knowing that even if the engine suddenly cut out, I could get comfortably across by coasting if necessary.
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...I could get comfortably across by coasting if necessary...
Same here, and I like to see enough spare road on the other side.
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In Harleyman's neck of the woods. Driver has been arrested.
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>> In Harleyman's neck of the woods. Driver has been arrested.
>>
Some accounts say that the lorry failed on the crossing. The barriers apparently came down on the lorry, I'd guess between the unit and trailer. Whether this is why the lorry stopped I don't know. It's about five miles from Whitland (where the train would have last stopped) and trains go along that bit of line at a fair lick; there's a bridge under the A40 just west of the crossing, followed by a curve, which might have impeded the train driver's view ahead.
Assuming the lorry driver was experienced (and you don't send novices out with a full load of straw) he should've phoned Whitland signal box, but it may be that it was by then too late for the signalman to do anything; it seems he was not in his cab at the time of impact so this may well have been the case. Given that the train was not de-railed and going by witness accounts, it seems that the train driver managed to knock quite a bit of speed off before impact.
Could have been a lot worse.
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There was a passenger's vid on the Wales news - showed the cab empty just after the accident.
www.bbc.co.uk/news/uk-wales-16256901
The citizen journalist has it.
Last edited by: R.P. on Tue 20 Dec 11 at 08:36
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Accident report published today:
www.raib.gov.uk/cms_resources/120927_R202012_Llanboidy.pdf (approx 1MB)
The accident occurred because the lorry driver did not telephone the signaller for
permission to cross and because local factors encouraged him to take a line towards
the right of the road.
Road signs, in English and Welsh, on the approach to the crossing instructed drivers
of large or slow vehicles to phone the signaller for permission to cross the railway.
The road signs defined the terms ‘large’ and ‘slow’ and the lorry and trailer were of
such a length, and were likely to have been travelling at such a speed, that the lorry
fell within the scope of both of these terms.
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Makes interesting reading. The point about the lorry being slightly over length is a useful wriggle for Network Rail, and a tad unfortunate for the operator. I would suggest that any articulated vehicle or drawbar outfit would have suffered the same fate regardless of length, especially if loaded with straw which is notoriously unstable. That crossing is "level" in name only; trust me, I use it to deliver feed to that same farm. The two previous accidents involved rigid vehicles.
Personally, given the relative proximity of the crossing to Whitland station where AFAIK all passenger trains on this line stop, it would also make sense to introduce a lower speed limit on that section, to give trains a better chance of stopping. It would also perhaps be sensible to move the treadles which control the crossing further back, so that the lead time between the train hitting the switch and arriving at the crossing is increased. Frustrating for drivers, as anyone who's waited for trains on the ECML will know, but ultimately much safer.
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>> You dont stop
>> hundreds of tons of train at 50 mph in 17 seconds.
>>
Thanks, Zero.
A point which is lost on many motorists.
our local morons have it down to a fine-art - a few years back a minibus taxi driver drove past NINE stopped cars and shot the half-barrier. Unfortunately for the kids in the minibus, he misjudged. 11 dead, IIRC. 11 charges of murder.
Then, earlier this year, some clown driving a truck loaded with farm-workers tried the same thing. 30-odd dead.
It seems that some folk equate trains with road vehicles - hey, we can do this with cars, so why not with trains?
I had a guy in my car once who was wondering why I didn't 'gap it' on a right turn, across traffic - 'hey, they have brakes!' was his idea.
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>> You dont stop
>> hundreds of tons of train at 50 mph in 17 seconds.
>>
It's not far off though,...
The weight of the train has nothing to do with how long it takes to stop - what matters is the adhesion between the wheel and the rail.
>> v=50*1609.3/3600; % initial speed in m/s
>> u=0; % final speed
>> t=17; % time in seconds
>> a=(v-u)/t % acceleration in m/s^2
a =
1.3148
>> a/9.81 % acceleration in g
ans =
0.1340
So, the rate of braking needs to be 13.4% of g. Typical UK train emergency braking rates are 12.5% of g - some do stop at 13% of g. So, it's a very close thing!
>> a_emergency=0.125*9.81; % UK train emergency braking rate
>> t_UK=(v-u)/a_emergency % time to stop a UK train from 50 mph
t_UK =
18.2274
Last edited by: Number_Cruncher on Thu 27 Sep 12 at 19:16
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Brake retardation isn't constant surely - wheels heat up, brakes heat up, and higher speed = more kinetic energy (heat) to dissipate initially.
ie. a very fast train cannot brake at as high a rate of g as a slower train.
And a very heavy train will overheat/fade the brakes faster (although I presume brakes are designed to last for one Vmax stop without fading).
Last edited by: Lygonos on Thu 27 Sep 12 at 19:37
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>>Brake retardation isn't constant surely -
The limiting factor - just like with a car - is the friction between the wheel and the "road".
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>> The limiting factor - just like with a car - is the friction between the wheel and the "road".
Absolutely, but do hot wheels have the same friction co-efficient as cold ones, and do rails have fairly similar frictional values independent of weather/temperature.
And can the brakes maintain maximum retardation throughout while avoiding wheels locking?
If not, then the limiting factor is the brakes being able to dump heat/avoid fade.
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12.5% of g is what the brakes are typically limited to. Yes, if there are leaves on the line, the wheels will slip first.
The brakes themselves are capable of significantly more than 12.5% braking force, they can lock the wheels, and the details of the brakes themselves are largely irrelevant.
Freight trains are a bit of an exception - but, not due to their mass.
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Presumably there is enough over-engineering in the brakes to prevent them fading during an emergency stop, and the wheel-track interface can supply enough friction to maintain 0.125g ?
Over 20 yrs since I did engineering - I've no idea what values of non-slipping friction coefficents smooth steel has!
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>>and the wheel-track interface can supply enough friction to maintain 0.125g ?
In good conditions, yes. Leaves on the line?, the wrong kind of snow?, no!
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18 seconds is still going to seem too long to a driver bearing down on a stalled petrol tanker 100 yards away at 50 mph...
I think some steam engines used to have a device for pouring sand onto the rails to improve traction in icy or wet conditions. But I think it was for acceleration not braking.
King's Cross and Birmingham were both terminuses down holes, difficult to haul big trains out of in the dead of winter. Or so an old experienced engine driver told me once.
Indeed the Roundhouse in Chalk Farm originally housed a huge horizontal steam winch used to help trains out of the King's Cross hole with a big cable.
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>>100 yards away
>> s_emergency=(v^2 - u^2)/(2*a_emergency)
s_emergency =
203.7042
So, it would take a train just over 200 m in braking distance from 50 mph.
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I'm sorry, but your maths bares no relationship to real life. A 55mph class 66 loco with 25 ore carriers will not stop in 200 metres, no way no how.
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>> I'm sorry, but your maths bares no relationship to real life. A 55mph class 66 loco with 25 ore carriers will not stop in 200 metres, no way no how.
If every wagon has similarly effective (and fade-free) brakes the number of wagons is immaterial.
p.s. I've no idea how well braked wagons are - presumably better than a Halfords trailer!
Last edited by: Lygonos on Thu 27 Sep 12 at 20:31
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Z has a point.
The freight train braking will be slower, but not due to the train's weight - more due to the train's length.
As the pneumatic signal must pass along the length of the train, and this process isn't quick, you can get the situation with a long freight train where there is a significant delay between the driver applying the brake lever and the rearmost vehicles applying their brakes.
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Are the air brakes connected to a single reservoir for a train rather than one per carriage/wagon?
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There are usually local reservoirs and relay valves on each vehicle, but, the pneumatic signal still needs to travel along the pipe to activate them.
The time delay between applying the brake and getting meaningful braking is longer in any train than it is in a car, but, long trains are much worse in this respect than short ones.
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Why not electronic control on each wagon or is a physical connection still required in the same way that car steering wheels have a direct link to the steering rack?
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>>Why not electronic control...
I'm not sure.
Most of the work I did was on older trains. Work which frequently cropped up was when a company wanted to extend the life of existing stock, we would help provide an engineering justification.
One project I worked on was when an operating company wanted to increase the rate of braking from 12.5 to 13%. We advised them not to do this, as the mechanical loads would compromise the already near life expired bogie frames. At design time, the once per wheel revolution fluctuation in braking load (brake judder effectively) had not been taken into account, and the original fatigue calculations were, therefore, not robust.
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>> Why not electronic control on each wagon or is a physical connection still required in
>> the same way that car steering wheels have a direct link to the steering rack?
Its a hostile place, a railway freight wagon, no easy place to implement electrics/electronics Plus there is no standard electronic control interface standard between all the different types of locos (owned by different train operating companies) and all the different types of wagons (owned by hundreds of different freight companies). The only standards are the physical coupling and the brake pipe connections.
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>> Indeed the Roundhouse in Chalk Farm originally housed a huge horizontal steam winch used to
>> help trains out of the King's Cross hole with a big cable.
I dunno, a Yorkshireman here giving London geography lessons to a mini- cabber. Tchaa!!
Chalk Farm is on the line out of Euston rather than Kings Cross.
In early days trains out of Euston were hauled up Camden Bank by cables. Though whether the machinery was in the Roundhouse I don't know.
Kings Cross can still be difficult of exit for today's diesels or electrics. What it was like when Copenhagen Tunnel was full of smoke and steam is a 'mare.
Wasn't Zero's dad loco man?
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Who's this Yorkshireman Bromptonaut?
You're right about Euston of course. King's Cross and St Pancras were later and aren't quite in the same place. I think the Roundhouse did originally have the engine and the big horizontal cable drum. But perhaps it wasn't used for long.
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>> Who's this Yorkshireman Bromptonaut?
I was born and brought up around Leeds. Flat vowels still give me away after thirty years working in 'the smoke'. My house has a garridge and a mow the grass not graaaass.
The maternal side's family were rooted in mining round Astley/Bowers Row but Dad was an offcomer from t'other side of the Pennines.
Last edited by: Bromptonaut on Thu 27 Sep 12 at 20:35
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'I was born and brought up around Leeds.'
Not far from me, whereabouts in Leeds?
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>> 'I was born and brought up around Leeds.'
>>
>> Not far from me, whereabouts in Leeds?
Horsforth then Guiseley, pupil at Aireborough Grammer School 71-78
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Too far out to be a proper loiner then ? ;)
South side plus a bit for me.
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>> South side plus a bit for me.
Where's that in terms of suburbs/pits?
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More west of wakey tbh, but was about the same to the centre of leeds as it was to wakefield. It was in the Heavy Woollen district, there was only one pit really close by and that has been shut quite a while when I was growing up.
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>> Wasn't Zero's dad loco man?
He was, but was an LNER man based at Stratford, so driving out of Liverpool street, Broad Street and Temple Mills. He did relate tales of driving freight steam trains through the Snow Hill tunnel, even in to the underground goods station at Smithfield, which was a right hell hole in the steam days according to him.
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The LNER had another hell-hole in the Woodhead tunnel. In steam days, in the old tunnels, the crew often had to vacate the cab and get as low as they could on the cabside steps, hanging on for dear life !
Later, crews were issued with respirators, which must have made the job more tolerable.
Ted
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> Wasn't Zero's dad loco man?
Hereditary eh?
;-)
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Including the receding hair line man
Last edited by: Zero on Thu 27 Sep 12 at 22:39
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Try a less abrasive headboard / longer bed. Or give up the trainspotter bobble hats. Restrict growth and encourage lice apparently.
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>> >> You dont stop
>> >> hundreds of tons of train at 50 mph in 17 seconds.
>> >>
>>
>> It's not far off though,...
>>
It does not quite work that way,
With a long train one issue is that the train brakes are not controlled in the same way as vehicle berakes. If all you did to apply the brakes was increase air pressure in a pipe then the brakes in the first wagon qwould apply immediately but the brakes in the last wagon (there may be 50 of them) don't start applying for some time. This means that the front of the train could be stationary before ht ebvack of the train has started braking and you get a collision in the middle of the train and a derailment.
To avoid this there is a signal pipe (where a reduction in pressure applies the brake) and each wagon has a timer which slowly applies the brake and the intention is that the brakes are appliesd slowly along all of the train. I was scared the first time I sat in the cab of a coal train and watched the driver apply the brake, from the gauges I saw the brake pipe pressure (Signal pressure) fall but it was 5-10 seconds before the brake cylinder pressure (brake application) started to rise and getting on for 30 before he had a full application.
Normal adhesion on rail is considered to be 8-10% due to oil, water and rust. Can be far worse.
Most passenger trains use a different system bit a 125 mph passenger train cannot stop in the distance the driver can see, even on straight track - more than a mile.
Partly why passenger trains have had anti lock brakes since the 70s - when did you get them on your car.
Vacuum braking was worse but even that was better than the old system of only having brakes in the locomotive and the guards.
Now trams - they are very different. They have an electromagnetic emergency brake that effectively sticks them to the track. You don't want to be a standing passenger when it is applied.
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My paternal granddad was a (steam) train driver. As was usual in those days he started off as an engine cleaner, then progressed to fireman, and finally driver.
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A very light sentence IMO, considering the damage to the train, risk to lives of passengers, costs of disruption and diversions and degree of ignorance displayed by the driver.
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>> A very light sentence IMO, considering the damage to the train, risk to lives of
>> passengers, costs of disruption and diversions and degree of ignorance displayed by the driver.
>>
Suspect he's lost his job and has little prospect of further employability. Three hundred hours community service will take quite a while to discharge too.
Not sure locking him up would serve any purpose either in retribution or deterrence to others tempted to try same thing.
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The driver had previous with several FPN from VOSA , the company he drove for had been fined by VOSA previously.
And he was a complete turkey, you are crossing a railway with a long rig, and the sounder starts and the half barrier descends.
What does a half sensible person do? you carry on and break the barrier and get the rig off the crossing.
What did he do? stopped and got out.
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>> What does a half sensible person do? you carry on and break the barrier and
>> get the rig off the crossing.
>>
Agreed. Your solution is excellent. However, it obviously never occurred to the driver at the time.
Not everyone is like you.
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>>
>> >> What does a half sensible person do? you carry on and break the barrier
>> and
>> >> get the rig off the crossing.
>> >>
>> Agreed. Your solution is excellent. However, it obviously never occurred to the driver at the
>> time.
>>
>> Not everyone is like you.
>>
He sounds a bit like a driver that would swerve into oncoming traffic or a tree to avoid hitting the car in front of him.
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Another level crossing crash - Bigtee
