I reckon an RPi type camera would be perfectly sufficient to estimate speeds, probably to a higher accuracy than you ask. Edit: a quick search led me to this h

I reckon an RPi type camera would be perfectly sufficient to estimate speeds, probably to a higher accuracy than you ask. Edit: a quick search led me to this https://gregtinkers.wordpress.com/2016/03/25/car-speed-detector/ https://gregtinkers.wordpress.com/2016/03/25/car-speed-detec... and this https://github.com/pageauc/speed-camera https://github.com/pageauc/speed-camera