Tube line distances

Does anyone have accurate distance information for any if not all tube lines. I'm looking for accurate distances of stations, overbridges, tunnel portals, crossovers etc, so that I can record and measure speeds. This is helpful but not necessary for open air sections cos a decent GPS can record that information, but underground there is no other way to determine speed other than average between stations or known reference points suitable for timing. I'm primarily interested in Central and Victoria lines, but all others too if available.

Thanks in advance ;D