Quote:
Originally Posted by 27vet
I would say that there should be an automatic disconnect for the propulsion and automatic brake application if a train enters a station / dead end too fast.
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This is quite a dilemna. Here in the UK on the mainline railway, nearly all passenger buffer stops have TPWS Overspeed Grids placed in the rear. These will cause the train's Emergency Brake to apply if you pass over them at a speed in excess of 10 mph (ish). Also on the Northern City Line and other sub-surface railways there is Moorgate control, where a series of tripcocks lower after a preset time. The train operates treadles as it moves towards the stops.
But sometimes it's not that simple because there are some platforms which are uphill, and so rolling over the grids/treadles at only 7.5 mph (the unofficially recommended speed) may cause the train to come to a stand well short of the stops. It is universally agreed that it is HIGHLY undesirable for the driver to have to take power as he approaches the stops - that defeats the whole object of getting him to reduce speed in the first place. But sometimes you just have to !
And of course if you hammer into the platform you'll probably beat the system anyway - certainly on a TPWS fitted system. As mentioned before the rulebook requirement is to be doing a maximum of 15mph at the platform ramp - If someone comes in at 30 the Emergency Brake probably won't stop the train before it whacks the stops. But the system is set up as it is because the majority of buffer stop collisions have been at low speed, often due to driver misjudgments.
You might ask why haven't we thrown lots more money/technology at it ?
Well..
1) It doesn't happen very often and not very many people have been killed - so it's the cost/benefit ratio argument
2) Very soon in this country ERTMS will remove decision making about speeds away from the driver. If the onboard computer doesn't like the speed you're doing it will stop the train itself.
HTH, BW