I am certain that third rail electrics can be designed to match the speed of any catenary electric, but that does not mean it will be done.
The limitation is the voltage, High speed trains, really high speed, all use very high-voltage transmission because of the power involved. 12,500 or 11,000 volts seems minimum, as with Acela. The Euopreans and Chinese are all 25,000V like New Haven north to Boston on Acela and other NEC trains. Haqving that kind of voltage on a third rail would result in shorts, because of the short distance from third rail to ground rail, the running rails.
But one could design high speed trains using 1000V DC or 700V AC which would be safe with third rails, but nobody seems to want to go that route.
There is nothing inherently better about a pan rubbing along a wire than a third rail shoe rubbing along a third rail. Except for better opporunity for far better insulation.
In 1977 I was aboard a late Jamaica to Penn Station train which was filled with fans from a trip to Montauk. A stop watch to the mile posts indicated a litte over 100 mph. So, I would say, we don't know how fast they really could go. We do know that cat electrics go faster, that diesels are capable of more, and that given the right circumstances (straight away, unlimited steam supply) a steam locomotive some say is unlimited.
MNRR and LIRR both have set speeds over ninety but below 100. Capability of equipment and engineer is the next dependent thing.
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How fast can trains using third-rail traction go?
Some people say 90 MPH on the LIRR. Others say less. Does over- and under-running make any difference?
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