alt Hacker NewsI know nothing about railways, but is there any sort of Time Domain Reflectometry (TDM) technology that railways use to detect issues with the rails?
I suppose with the distances we're talking about and the resistance of steel this isn't visible without a whole bunch of signal generators?
Edit: Be sure to read jiggawatts' reply below.
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They use “test” cars that have bright lights or xenon flashes pointing down. They take thousands of pictures of the track every night and store the images in a database that can match them up precisely so you can see cracks growing over time like a movie.
I also remember reading about an application of fibre optics where a long strand is placed directly under each rail. Pulses of light through the fibre are reflected at the points where axles press down on the rail and compress the fibre. Similar techniques can be used to detect accidents and (completely) broken tracks.
This was sabotage of the control equipment.