A 3rd rail needs to be designed to play nicely with what’s around it, e.g. kids poking it with a metal pole. It also requires power to be delivered to it. It also requires a way to repower a section when roadworkers need to move the rails. It also turns a run of paving slabs into a full blown circuit, requiring more training to install.
If you’re intending it to only be at the stations, then you still need to deal with the curious kid issues, as well as dealing with weather related issues. E.g. what happens if the 3rd rail is in a 5cm deep puddle?
The other option would be inductive charging, from below. That has its own problems however, the biggest being efficiency.
A 3rd rail needs to be designed to play nicely with what’s around it, e.g. kids poking it with a metal pole. It also requires power to be delivered to it. It also requires a way to repower a section when roadworkers need to move the rails. It also turns a run of paving slabs into a full blown circuit, requiring more training to install.
If you’re intending it to only be at the stations, then you still need to deal with the curious kid issues, as well as dealing with weather related issues. E.g. what happens if the 3rd rail is in a 5cm deep puddle?
The other option would be inductive charging, from below. That has its own problems however, the biggest being efficiency.