Overview: In today's episode, Maddie is looking at useful lights. She shows us how traffic lights work so that vehicles can travel safely through a road junction. She visits a traffic control centre and uses a special camera high up in the air to see all the traffic in action at a busy junction. Next, Maddie visits a factory where emergency warning lights are made using computer designs. She helps to pick the components to make the lights and, using special cameras, we see how all the wires fit together to make a police light! Maddie shows us the light being fitted on top of a police car and tested for the first time.