jis
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Yup. And actually one could come up with a scheme to even use the Induction coils to enforce certain speed limits, but that has typically not been done. The reason is it would have reduced average speed and hence throughput of trains dramatically. Incidentally, some of the PTC freight operators are already discovering the effect of PTC on throughput (negative), though nothing as dramatic as it would have been if only Induction Coils were used. mainly this effect happens because the automatic system is more conservative and does not push the safety envelope as far as a human operator tends to.How about the ancient 'speed signals' on the New York subways? They force the train to slow down, or else, if the train goes thru the red signal, the tripper will cause an emergency stop...
Incidentally, the rear end collisions on Manhattan bridge happened in spite of the New York Subway ancient stop enforcement system. The problem was that the train was overspeeding when it passed the auto stop level triggering its brakes, and it ran into the train ahead before it could stop completely.
The ATSF ATS also has exactly this problem. It is not guaranteed to stop the errant train before it fouls the interlocking that it is protecting, and in addition it cannot enforce civil speed limits, both TSR and PSR as required by PTC. hence anyone who proposes to have ATS substitute for PTC is just ignorant enough not to know know what either or both are and what the PTC regulation is.
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