“Evidence shows that a vehicle travelling at 30mph will still be travelling at 24mph in the time it would take a car travelling 20mph to stop.
“Mae’r dystiolaeth yn dangos bod cerbyd sy’n teithio 30mya yn dal i deithio 24mya yn yr amser y byddai’n gymryd i gar sy’n teithio 20mya i ddod i stop.