Race track timing

[djahugen]

Hi,

I'm looking for a way to time a horse race. There is a track of 150 meters long. The horse must walk the track up and down and I need to record both times. The most ideal way would be with some kind of dual stopwatch, started and stoped by a optical sensor. The sensors may be wired as well as wireless.

Anyone have an ideal how to build such a timer??