How feasible would it be for trains to have 'wheels on rails' sensors ?

Given planes have 'weight on wheels' sensors, how feasible would it be for trains to have 'wheels on rails' sensors ?

choochoochoo said:

....but given planes have 'weight on wheels' sensors...

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Planes leave the ground as a normal part of their lives...

cats_five said:

Planes leave the ground as a normal part of their lives...

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But it wouldn’t be a very normal part of their life for the landing gear to be allowed to retract whilst on the ground.

It ought to be practical to devise sensors that tell the driver to stop and examine if there is sustained and hugely excessive vibrations in any vehicle in the train, certainly in passenger stock which has (the potential for) complex comms between vehicles. Not as a quick cheap retrofit but aeroplanes do tell their pilots about the engines vibrating.

Might be a bit naive in my understanding of how electricity and track circuits operate, but if track circuits are completed by wheels on an axle touching the rails, could a sensor be placed on that axle to detect when its completing a track circuit and thus send an alert if it might have derailed and is no longer completing a track circuit ?

Yes, but then you just have another thing with a sensor on it that throws up more faults than it's worth.

choochoochoo said:

Might be a bit naive in my understanding of how electricity and track circuits operate, but if track circuits are completed by wheels on an axle touching the rails, could a sensor be placed on that axle to detect when its completing a track circuit and thus send an alert if it might have derailed and is no longer completing a track circuit ?

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No, because not all the railway is track circuited. A lot is Axle Counters (they detect the electromagnetic field of a passing wheel flange, but do one side therefore counting axles, on the entrance and exit of a track section). Also a lot is non continuous train detection or tablets/token/radio tokens or Signaller looking out the box window for a tail light (or using a tail light camera or train crew using train arrived complete plunger). Ive probably forgotten something in that quick list of the many ways the GB Mainline network knows where trains are. Also different track circuit types use very different frequencies or voltages and traction return on the Mainline goes through the axles. It probably isn't impossible to have a comparison list to work out if it is a track circuits not traction return but would be very expensive and not worth it for the little benefit (low derailment rialsk and %of Network that is not Track Circuited

choochoochoo said:

Might be a bit naive in my understanding of how electricity and track circuits operate, but if track circuits are completed by wheels on an axle touching the rails, could a sensor be placed on that axle to detect when its completing a track circuit and thus send an alert if it might have derailed and is no longer completing a track circuit ?

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Track circuits are fail safe i.e. the wheels/axle break the circuit.

a_c_skinner said:

It ought to be practical to devise sensors that tell the driver to stop and examine if there is sustained and hugely excessive vibrations in any vehicle in the train, certainly in passenger stock which has (the potential for) complex comms between vehicles.

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It's temperature sensing, rather than vibration, but onboard "hot axle box detection" systems have been fitted to some new build fleets.

D365 said:

It's temperature sensing, rather than vibration, but onboard "hot axle box detection" systems have been fitted to some new build fleets.

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Didn't know that and the level of vibration when an axle derails is so sustained and so marked it shouldn't be difficult to make such a system that isn't hugely costly and doesn't produce too many false alarms.