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Originally Posted by Joanna
Hi everyone,
I am writing an article about past/present/future of long distance passenger trains.
These trains used to consist of coupled coaches but this solution is being replaced by permanently coupled trains. I guess it is because of (future) implementation of ETCS level 3 (where axle counters won't be needed anymore) but do you have any other ideas why is it happening? What can be benefits of using permanently coupled trains?
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I don't think ETCS (the 'train part' of ERTMS) is the cause for fixed formation trains. In the current issue of Rail magazine (843), Network Rail has stated that ETCS will first be introduced to freight locos in the UK, and of course those are all not permanently coupled. ETCS really only affects the driving cab of a train as it 'supervises' the way the train is driven. All the other vehicles just follow behind.
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Originally Posted by trophy
in the past trains were loco hauled which required the loco to be run round the train at the end of a journey,with a fixed formation with a driving cab at each end as used now this is not required.
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...sums it up pretty well. For passenger operation, being able to 'change ends' saves time and removes the need for run-round loops at terminii.
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Originally Posted by ianrail
I can see a disadvantage in that if one carriage develops a fault, the whole train needs to be taken out of service rather than just removing that one carriage.
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Is a good point, but servicing and maintenance is getting smarter. We now have drive-through wheel lathes, where a remote-controlled tug can haul the unpowered train through the lathe and skim the damaged wheels in situ.
Most trains are modular, so sections can be taken out and replaced on an overnight inspection.
Also there is built-in redundancy. Trains now have multiple sets of the vital components. Multiple engines or traction motors strung out along the length of the train. If one or two of them dies, there's enough power to get the train home. There are also duplicates of things like Compressors for air, Converters for traction motors and auxiliaries (110V DC for the battery charging/ 220V for saloon lighting and power sockets).
With mobile phone technology and internet access the train can actually be fixed remotely whilst its going along. Everything is monitored by an onboard computer and this data is relayed continuously to a 'duty fitter' who can not only view all systems on the train on his laptop, but can alter them as well. So when the train comes into a depot on a regular visit there is already a list of things to fix and the components are already ordered.
So with all this you'd expect the trains to run like clockwork wouldn't you ? The trouble is many train faults just come out of the blue. Like when some little s*** flushes all the paper towels down the loo and the resulting flood shorts the power out. Or a late passenger pushes the doors so hard they break the safety sensors. Or a driver presses the Pantograph Up button when there's no overhead wire.
There's always something we didn't see coming.
HTH BW