We have 20mph zones in cambridge, but how on earth do we enforce them? The road I live on with my young children is a rat run for building works vehicles, taxi’s and regular cars and they are not adhering to the zone. Also. We have bikes, in ese zones, breaching red lights at pedestrian crossings at alarming rates ( we have statistical evidence to back this up). What to do?! The 20 signs are so small I fear they go unnoticed.