Carbon monoxide in tunnels

[kermit]

Never really considered this before, but if a diesel or steam train has to stop in the middle of a long tunnel, can carbon monoxide become an issue?

 

[broadgage]

In theory, yes it could be a problem, but in practice it tends to be a non issue unless the tunnel be exceptionally long or the engine produces exceptionally large amounts of carbon monoxide.

Diesel engines produce relatively little carbon monoxide unless defective, petrol engines are far more dangerous but of course are virtually unknown for full size locomotives.

A steamer if in good working order and sensibly fired should produce very little carbon monoxide as the coal should be burnt completely with a slight excess of air.
If however the stoking be excessive or the draught be impaired then a steam locomotive can produce significant carbon monoxide, and persons exposed in a confined space would be at some risk.
Carbon monoxide is a cumulative poison and therefore far more dangerous if a train is detained in a tunnel or proceeds abnormally slowly rather than passing at line speed. A higher speed not only reduces the exposure time but also tends to draw fresh air into the tunnel. Working the engine fairly hard also promotes perfect combustion by improving the draft.

Accidents are therefore rare but have occurred. Dozens, perhaps hundreds of lives were lost to suspected carbon monoxide poisoning during the last war when the steam hauled "black market express" either stalled or slipped to a stand in a long tunnel in Europe.

http://en.wikipedia.org/wiki/Balvano_train_disaster

 

[Pigeon]

In particularly badly ventilated situations it has been found necessary to provide crews with breathing apparatus - must have been fun driving a steamer wearing that...

http://www.douglas-self.com/MUSEUM/LOCOLOCO/sp4882/sp4882.htm

Something similar was tried on the Garratt Worsborough banker but apparently the crews preferred to suffocate rather than breathe through something someone else had breathed through!

I think pretty much every collection of reminiscences of steam drivers/firemen that I have read includes at least one episode involving a clapped-out, overloaded loco struggling up a bank in a tunnel at walking pace with the crew wondering whether they would make it out the other end before they collapsed, and terrified in case they stalled. In some cases one or other of them did collapse.

Carbon monoxide isn't the only problem. Sulphur dioxide is also significant. There is a fair bit of sulphur in coal, and unlike carbon mon which has an insidious effect, sulphur dioxide is readily detectable and produces a choking effect. Also there is plain old smoke, of course, and simple exhaustion of available oxygen by the fire.

Then, too, there were the occasions when a pilot locomotive was attached to help a train up a bank in tunnel and the crew of the train engine would use this as an opportunity to take it easy for a bit and let the crew of the pilot do all the work. To which the pilot crew might respond by finding a suitable piece of red hot metal and widdling on it, so the train engine driver would open it right up to try and get out of the stench as fast as possible

 

[apk55]

There was the Balvano train disaster of 2/3 March 1944 in Italy when 426 people died when a train stalled in a tunnel.

http://en.wikipedia.org/wiki/Balvano_train_disaster

 

[broadgage]

Breathing apparatus was indeed tried in exceptional cases, with varying degrees of success.
I believe however that the article linked to in post #3 is in error. It is suggested that oxygen from a cylinder or oxygen generator was used, this I very much doubt, apart the costs and logistical problems oxygen would have been very dangerous in the cab of a steam locomotive.

AFAIK all systems used simple compressed air from the main reservoir used for air braking. This air was not treated to remove carbon monoxide, but would be a considerable improvement over the air in the cab for two reasons.
Firstly, most of the air would have been compressed into the main reservoir by the Westinghouse air pump whilst out in the open, before entering the tunnel.
Secondly the air inlet into the air pump was at low level where the air was cleaner than at head height in the cab.
The air was passed through a throttling valve so as to give an ample flow even under rapid breathing. The exhaled air and the surplus air supplied simply escaped. The expansion of the air from main reservoir pressure down to virtually atmospheric pressure would have produced a noticeable and welcome cooling effect, heat stress was probably a problem in some tunnels.

During the last war, some UK crews tried using the gas masks supplied in case of enemy gas attack, in tunnels with limited success.

 

[Pacerpilot]

Imagine how much fun it was sat in here for 10 hours. Four locks a plus numerous road railers idling away. They had huge fans drawing air through the tunnel but I still got the eyes stinging a bit.

https://www.flickr.com/photos/88406088@N02/14545191538/

 

[ac6000cw]

The problems of operating steam traction through long tunnels (particularly ones bored through solid rock under mountains, where it was virtually impossible to provide ventilation shafts) is what led to local electrification schemes in some cases i.e. through the tunnel plus the heavy gradients on either side. I assume these problems are what led to the Swiss into becoming early pioneers of mainline electrification.

In the US, a combination of increasing train weights and larger locomotives eventually made steam operation through some tunnels intolerable for the crews, so for example two out of three mainlines which crossed the Cascade Mountains in the north west corner of the US where electrified over their mountain passes in the early years of the twentieth century.

Further south in California, Southern Pacific railroad tackled the problem by developing (oil-fired) steam power with cabs at the front - the famous 'cab-forwards' https://www.youtube.com/watch?v=n_ErZ5SgkVw and http://en.wikipedia.org/wiki/Southern_Pacific_4294

All of the tunnel electrification schemes were eventually dismantled with the arrival of diesel power, but even today there are some long tunnels with large doors at one end which close after the passage of each train, and powerful fans push fresh air into the tunnel to force the accumulated diesel fumes out of the other end (so you get a smoking tunnel portal for a few minutes ) - the Moffat Tunnel in Colorado is one example of this.

 

[PHILIPE]

I recall back in steam days on the HOWL and a heavy freight climbing up from Knighton with a Banker on the rear and the footplate crew often having to put a wet handkerchief over their mouths when going through Llangunllo tunnel.

 

[Ploughman]

I have worked on track renewals in tunnels such as Standedge and Bramhope.
During the renewal with Spoil trains and class 56's plus diggers and generators you could see the smog level dropping down from the roof until you could not see 10 metres.
Depending on the nature of the smog the Scientifics guy with the Air Quality meter would tell all to stop and get out for a while.
Not to bad in a short tunnel or even in Standedge due to the cross tunnels into the disused bore. But in tunnels like Bramhope normal practice was to head upwind to a vent shaft and wait there till called back.
We did use big fans to assist the normal air flow but sometimes the wind changed during the shift and the fans were blowing into the wind for a while.

I hated tunnel work.

 

[theageofthetra]

The SP cab forwards had air masks too. They were lifted from decommissioned aircraft during and after WW2. The one in the Sacremento rail museum certainly had this had set up. Another problem in the US was the use of intermediate locos in the middle of long freights. Until fully computerised control was introduced some of these intermediates had crew in them. The conditions were horrific as the leading units used up so much air on graded tunnels and snow sheds, the clag produced was huge.

 

[edwin_m]

Train runaway on the S&D due to crew asphyxiation:

http://www.railwaysarchive.co.uk/docsummary.php?docID=1999

I recall going through the Moffat Tunnel in Colorado in 1990 when the train stopped very suddenly under emergency lighting. The PA announcement was that the driver had been ordered to shut down due to high levels of gases in the tunnel. Got moving again after a couple of minutes.

 

[ac6000cw]

Another problem in the US was the use of intermediate locos in the middle of long freights. Until fully computerised control was introduced some of these intermediates had crew in them. The conditions were horrific as the leading units used up so much air on graded tunnels and snow sheds, the clag produced was huge.

You mean like this - https://www.youtube.com/watch?v=aBh0aEnYr-A (that tunnel is only 360m long, and some of the locos are 'tunnel motors' with air intakes moved down to frame level to help with the engine 'breathing')

 

[R4_GRN]

Dundee station at the east end from broughty ferry must have had the same problem as the line run under the main road for a fair length. The signal box at the east end of the platform was underground and needed lighting all the time. I imagine when steam trains were running the fumes must have been bad although I visited the signal box only once I did not notice the fumes, might have been due to my youth might have been due to no trains at the time.

 

[Pigeon]

The problems of operating steam traction through long tunnels (particularly ones bored through solid rock under mountains, where it was virtually impossible to provide ventilation shafts) is what led to local electrification schemes in some cases i.e. through the tunnel plus the heavy gradients on either side. I assume these problems are what led to the Swiss into becoming early pioneers of mainline electrification.

Switzerland has no coal but does have enormous capacity for hydroelectric power. So electrification makes sense for them in a way that it does for few other areas. In WW2 when they could hardly get coal at all they even converted steam shunters into electric kettles, with pantographs on the cab roof and immersion heaters in tanks connected to the boilers.

http://www.douglas-self.com/MUSEUM/LOCOLOCO/swisselec/swisselc.htm

 

[kermit]

Thanks for all the responses to my query - truly fascinating!