(26 Jul 2014, 1:10 pm)aureolin wrote Two completely different solutions. Buses need to use a combination of GPS and mobile data. GPS obviously for the vehicle to work out it's position, and mobile data to transmit it to a central control centre. I don't pretend to know an awful lot about rail, but I believe the rail system tracks the unique identifier of a registered train passing different 'check points' throughout the network rail infrastructure. Metro does the same, as you'll notice the next stop announcement always triggers at the same point.

You are right. I think we have all used real time trains and that is exactly how it works. For anyone who has not, an example is below.

http://www.realtimetrains.co.uk/train/G3...6/advanced