Signals in Tunnels

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Lucan

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There has been a reference to this old thread about the Woodhead Tunnel having a signal box within it to divide it into sections :

https://www.railforums.co.uk/threads/worst-job-in-history-woodhead.48451/

That thread is closed now, but I wonder about steam trains being stopped by signals inside tunnels. There must have been a danger of asphyxiation if the stop was prolonged. I know there was a terrible incident of a French troop train during WW1 where many men were asphyxiated in a tunnel, possibly following a crash or derailment, (I cannot find a reference to it now).
 
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ainsworth74

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I know there was a terrible incident of a French troop train during WW1 where many men were asphyxiated in a tunnel, possibly following a crash or derailment, (I cannot find a reference to it now).

The worst that I'm aware of was from 1944 when a freight train in Italy carrying hundreds of stowaways stalled in a tunnel and around five hundred people died of carbon monoxide poisoning:


In the evening of 2 March 1944 the freight train 8017 started from Naples heading to Potenza. It consisted of 47 freight wagons and had a remarkable mass of 520 tonnes; it also carried many illegal passengers.

The first part of the journey took place on flat railway, and the train was pulled by a E.626 electric engine. At 19:00 the train left Battipaglia and entered the steeper, non-electrified Battipaglia–Metaponto railway; the electric engine had been replaced by two steam engines (the 480.016 followed by the 476.058).

In Eboli some stowaways were forced off, but more boarded on following stops until they numbered about 600, making the train grossly overloaded. At midnight the train arrived in the Balvano-Ricigliano station, the last one before the disaster, where it stopped for maintenance on the engines.

At 00:50 the train restarted towards the adjoining Bella-Muro station, and reached a speed of about 15 kilometres per hour (9.3 mph). After 1.8 kilometres (1.1 mi) of travel, it approached the Armi tunnel, narrow and poorly ventilated, which is 1,968 metres (2,152 yd) long with a 1.3% incline. As the engines entered the tunnel, the wheels started to slide on the rails (which were wet due to humidity), despite the use of sand boxes, and the train lost speed until it stopped, with almost all the cars inside the tunnel.

The air was already filled with smoke since another train had passed shortly before, and the drivers' effort to restart the train caused the locomotives to produce even more carbon monoxide–laden smoke. As a result, the crew and stowaways were asphyxiated, so slowly that they failed to realize what was happening to them. Most died in their sleep. Of the few survivors most were in the last few wagons, which were still in the open air.

At some point the driver of the 476 locomotive tried to engage the reverse gear in attempt to exit the tunnel, but he fainted before suceeding. Moreover, he couldn't communicate with the driver of the other engine (which in fact continued to push in the forward direction) because the 476 was an Austrian-built engine with right-hand drive, while the 480 had left-hand drive as usual in Italian railways.

At 05:10 the Balvano station master learned of the disaster from last car's brakeman, who had walked back to the station. At 05:25 a locomotive reached the site but the many corpses on the track prevented it from removing the train from the tunnel; only some forty survivors in the last wagons could be assisted. At 08:40 a second rescue team arrived which hauled the train back to the station. Among the crew, only the one brakeman, and the second locomotive's fireman, survived.

Due to the large number of corpses, the wartime lack of resources, and the poverty of many of the victims, only the train staff received a proper burial; stowaways were buried without a religious service in four common graves at the Balvano cemetery.

I believe various US railroads had similar issues out west with heavy slow moving freight trains through the mountains in long tunnels and snow sheds which resulted in train crew being at risk of death. I think some US locomotives were actually fitted with breathing equipment for the train crew (I assume passenger services weren't affected as they were quicker) and certainly the Southern Pacific used quite a large number of 'cab forward' designs to try and get the train crew out of the smoke and fumes.
 

Mcr Warrior

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The intention of the (middle of the Woodhead Tunnel) signal box was to split the three mile tunnel into two shorter sections so that trains could then clear the shorter mile-and-a-half section in half the time, thereby increasing route capacity.

But how exactly would drivers have been able to see the mid-tunnel signals in such smoky conditions?

Not the best thought out of capacity-improving plans, methinks!

P.S. This old 2015 thread may be of interest.

 

edwin_m

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Normal practice was for signals in tunnels to be colour light, which would make them more visible as well as being small enough to fit in the available space.

Many mountain sections in the USA were electrified in the early part of the 20th century, one reason being to reduce the risks from steam locomotives in tunnels. A "cab forward" design wouldn't help the crew of the second and subsequent locomotives on a heavy freight train. The advent of diesels made this unnecessary and all of these local electrifications were later removed (or the lines closed completely). Long tunnels in North America today often have ventilation fans and sometimes even doors at the portals to allow fumes to be kept at a safe level. Some years ago while passing though the Moffat Tunnel on Amtrak, the train came to a sudden halt and the lights went out, and it was announced that the driver had been commanded to stop and shut down because fumes were exceeding the limit.

The above is a report into an accident at Bath caused by asphyxiation of the train crew in the steep, narrow and unventilated Combe Down Tunnel.

I am therefore led to the conclusion that both driver and fireman were overcome by smoke and fumes while passing through Combe Down tunnel, and that the engine emerged from the tunnel uncontrolled. Having regard to the falling gradient, it can be shown by calculation that, even assuming the engine was only just moving at the exit from the tunnel, it might well have attained a speed of 50 miles an hour or more at the foot of the gradient, in spite of the guard's brake application.
 

LowLevel

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The intention of the (middle of the Woodhead Tunnel) signal box was to split the three mile tunnel into two shorter sections so that trains could then clear the shorter mile-and-a-half section in half the time, thereby increasing route capacity.

But how exactly would drivers have been able to see the mid-tunnel signals in such smoky conditions?

Not the best thought out of capacity-improving plans, methinks!

P.S. This old 2015 thread may be of interest.


Woodhead Old Tunnels were an extremely inhospitable working environment. The old Tunnel box lasted such a short time that I don't what it's arrangements were, but certainly at the Woodhead end there were train operated gongs fitted to the track that alerted the crew to get off the floor where they used to lay with cloths on their faces trying not to suffocate when they needed to start spotting signals again.

Amazingly the gong survived until a couple of years ago in the service tunnel, along with a couple of signals, when the tunnel was capped. National Grid never bothered stripping the service tunnel of it's railway equipment and it featured the remains of signals, cable trunking, mile posts, the aforementioned gong etc.
 

Taunton

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Many mountain sections in the USA were electrified in the early part of the 20th century, one reason being to reduce the risks from steam locomotives in tunnels. A "cab forward" design wouldn't help the crew of the second and subsequent locomotives on a heavy freight train.
The Southern Pacific Cab-Forwards, only user of this type of significance, were big 4-8-8-2s, and were not permitted to double head. Furthermore they were oil fuel (this configuration would otherwise not be possible) and the fireman could just shut down the combustion in a moment if things got anywhere near difficult.

Fumes were not the only issue Southern Pacific faced in tunnels, heat was another, which in diesel days caused problems with cooling air not being adequate, and the diesel overheating and shutting down. They bought several generations of modified SD-40T and big SD-45T locos, T for tunnel, a special adaptation that GM did for them, with the cooling air intakes down at the bottom of the body instead of up at the top, and of course a whole series of equipment rearrangements inside to suit.

Separately, signals were installed in Polhill Tunnel, between Sevenoaks and Orpington, in the 1960s, to shorten the section. All electrified by then of course, but some ingenious signal sequencing only let a second train enter the tunnel if the first one in there had clear greens to exit, so the chances of being stopped inside the tunnel at a red, short of the first train breaking down, were almost nil. I wonder if it's still like that.
 
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edwin_m

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Separately, signals were installed in Polhill Tunnel, between Sevenoaks and Orpington, in the 1960s, to shorten the section. All electrified by then of course, but some ingenious signal sequencing only let a second train enter the tunnel if the first one in there had clear greens to exit, so the chances of being stopped inside the tunnel at a red, short of the first train breaking down, were almost nil. I wonder if it's still like that.
A track circuit failure causing it to remain occupied after the first train would probably be a more likely scenario. In other places (Haymarket tunnels I think) the signal spacing is maintained but the signal in the tunnel has no red aspect, so that if trains are following closely the second one has to wait at the portal until the first one clears the other end.
 

XAM2175

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I believe various US railroads had similar issues out west with heavy slow moving freight trains through the mountains in long tunnels and snow sheds which resulted in train crew being at risk of death. I think some US locomotives were actually fitted with breathing equipment for the train crew
It's still the case for at least one unventilated tunnel in New South Wales (specifically the Bylong or Ulan No. 3 Tunnel) that all persons on a train hauled through the tunnel by two or more locomotives must carry self-rescue breathing apparatus in case the train is stopped in the tunnel without the ability to restart.
 

hexagon789

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The pre-electrification Argyle Line had miniature semaphores but they were difficult to see in the smoky gloom, they were replaced by colour lights in 1956.
 

Trackman

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Going back to 1905 several Stockport County players became ill with sulphur fumes after passing through the Woodhead tunnel. I'm not sure if the train stopped or not.
God knows how that signaller in the middle went on.
 

Lucan

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It sounds like it would have been a really bad idea to have had a home or stop signal in a tunnel in those days (or even with diesels?). A distant perhaps, but with the home signal at least a train length beyond the tunnel exit.

It is amazing that in the early years, the London Metropolitan Railway and the District Railway got away with steam trains in tunnels in the central area. I know the stations were in pits open to the sky, and the crew would work up a head of steam during the stop, and then they would actuate some sort of fire damper and run to the next station on the head of steam. Even so .... and the cabs had no roof! But at the time it was believed that smoke was good for you (they said it in cigarette adverts), and doctors would prescribe trips around the Circle for patients with breathing problems. I have never heard of anyone dying on those trains.

 

Ashley Hill

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Corsham up distant was located inside Box Tunnel. It's remains survived until the preparation work for OHLE.
image.jpeg
Not my photo.
(Edit,apparently this is still in Box tunnel,I'm told it's clearly visible in the IET headlamps.)
Also Severn Tunnel had signals located within but were removed following a major incident . There are still emergency stop signals which are only illuminated when activated.
 
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