3 ms·
with metros the additional consideration is tunneling. generally speaking, third rail allows for a smaller tunnel diameter than overhead systems. (third rail i
by bobthepanda 5y ago
with metros the additional consideration is tunneling.
generally speaking, third rail allows for a smaller tunnel diameter than overhead systems. (third rail is located near the wider section of tunnel in the middle whereas overhead requires extending the height.)
- bluGill 5y agoThere are overhead rails you can use in tunnels. Nothing stops the high voltage arc issue (the whole advantage of overhead is high voltage), but without all the equipment to tension the cables you don't need as much room and the power will be one the middle of the tunnel. Anyone building new tunnel should allow the little extra room for overhead, but retrofitting may not be worth it.