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.
London Bridge station to the Big Four grouping in 1923. All of the railways of southern England combined to form the Southern Railway (SR), bringing the London Bridge complex under single ownership. The wall that divided the Chatham and Brighton stations was partially knocked through in 1928 to provide an easier interchange between stations. This allowed a greater range of platforms to be used for the increasingly frequent suburban rail services to London Bridge. Between 1926 and 1928 the Southern Railway electrified the SE&CR suburban lines at London Bridge using a third rail system, adapting the existing LB&SCR routes to it at the