Spanning 1.1 kilometres (0.7 miles) across the River Thames between Greenwich Peninsula and Royal Docks in London is the UK’s first-ever urban cable car. Detachable grips are connected to a continuously moving twisted steel cable, or haul rope. This haul rope is one long, 50-millimetre (two-inch)-thick cable that loops across the river and back again around two bullwheels inside the terminals on either side. It rotates at a line speed of up to six metres (19 feet) per second and slows down to ‘creep speed’ in the terminals for boarding and disembarking. The grips grab or release to slow down or speed up the cars. The main terminal contains the drive bullwheel which, powered by electric motors, turns to propel the cable. This is also the location of the various braking mechanisms, including the emergency brake behind the bullwheel, the service brake and the anti-rollback brake.