Hmm not too sure, it all depends what actually get recorded. If all the system knows is when and what speed you passed the last gantry and then this gantry, that's assuming that it does this it has no idea what speed you were doing as you approached. As it's variable I've seem people floor it between gantries and then slam on their brakes. If each gantry is independent then all it has is the cut in/off time when the speed goes up/down.