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The most expensive part of electrifying existing track is bridges and tunnels since they often have to be rebuilt to have enough clearance (especially in places
by theluketaylor 3y ago
The most expensive part of electrifying existing track is bridges and tunnels since they often have to be rebuilt to have enough clearance (especially in places like the UK where bridges are old and therefore very low. If all the trains have enough battery to move a short distance without the overhead wires suddenly the electrification project becomes pretty simple and non-disruptive and costs are really reasonable.
- cjrp 3y agoIs the clearance needed even if they're powered by the third rail? Or only for overhead pickup
- theluketaylor 3y agoOverhead only. But 3rd rail for long distances is really dangerous. Subways and metros use it since they typically strongly control access to the tracks and tunnels, but that really isn't possible when crossing whole countries.
- wkat4242 3y agoStill, you could use third rail in tunnels which can be tightly controlled, and overhead elsewhere. Dual trains exist, many metros have it too.
- rjmunro 3y agoIn the UK, 3rd rail is typically 600V (DC), where as overhead is 25kV (AC). So you need 40× the current to get the same power. For high powered intercity trains that run at around 1MW of power, it increases transmission losses substantially.