London's population has grown by a million in the last ten years. The city's roads are full up - yet 8 out of 10 journeys by londoners are by still by road. This means that 25,000 Transport for London workers now face a daily battle to keep the capital moving. Every morning, 8,500 buses carry six million passengers - double the number carried by the underground. 6,000 control them and the rest of road traffic, whilst 2000 dedicated police keep the roads clear by racing to incidents large and small. This is all overseen by the biggest traffic control centre in the world, which, unbeknownst to most of us, orchestrates our journeys every day.