Tower Bridge bridge's upper walkways. The pedestrian walkways are above the river at high tide. The main bridge deck carries two lanes of road traffic between two low-level pedestrian walkways across both suspension spans and the opening bascule section of the bridge, with the walkways separated from the roadway by fences. The roadway passes through each of the two towers, whereas the low-level walkways pass around the outside of the towers. One of the chimneys on the bridge, which are often mistaken for lamp posts, connects up to an old fireplace in a guardroom of the Tower of London. It is long-disused.
Tower Bridge day. The bridge is on the London Inner Ring Road, and is on the eastern boundary of the London congestion charge zone. (Drivers do not incur a charge by crossing the bridge.) To maintain the integrity of the structure, the City of London Corporation has imposed a speed restriction, and an weight limit on vehicles using the bridge. A camera system measures the speed of traffic crossing the bridge, using a number plate recognition system to send fixed penalty charges to speeding drivers. A second system monitors other vehicle parameters. Induction loops and piezoelectric sensors are used to measure the