Editing Tower Bridge (section)

=== 20th century ===
[[File:London Blitz 791940.jpg|thumb|left|Tower Bridge during the [[The Blitz|first mass air raid]] on London, 7 September 1940]]
[[File:Tower Bridge - 1950.jpg|thumb|Tower Bridge – 1950, BW Lee]]
[[File:SHort Sunderland V DP198 201.A Tower Br 16.09.56 edited-3.jpg|thumb|A [[Short Sunderland]] of [[No. 201 Squadron RAF]] moored at Tower Bridge during the 1956 commemoration of the [[Battle of Britain]]]]

After its opening, the City of London provided some funding to the police to pay for the policing of Tower Bridge, under an informal "compact". The Corporation of London (Blackfriars and other Bridges) Act 1906 (6 EdwVII c.clxxx) formally placed the bridge under the City of London's policing jurisdiction.<ref>{{cite web |url=https://democracy.cityoflondon.gov.uk/documents/s74250/Policing%20the%20Bridges%20-%20Appendix%201.pdf |title=Policing the Bridges and allocation of costs to the Bridge House Estates |publisher=City of London |author=P R E Double |date=September 2016 |access-date=31 January 2025}}</ref>

During the [[Second World War]], Tower Bridge was seen as a major transport link to the [[Port of London]], and consequently was a target for enemy action. In 1940, the high-level span took a direct hit, severing the hydraulic mechanism and taking the bridge out of action. In April 1941, a [[parachute mine]] exploded close to the bridge, causing serious damage to the bascule, towers, and engine room. In 1942, a third engine was installed in case the existing ones were damaged by enemy action.{{sfn|Milne|2020|p=153}} It was a 150&nbsp;[[horsepower|hp]] horizontal cross-compound engine, built by [[Vickers Armstrong Ltd.]] at their Elswick works in Newcastle upon Tyne. It was fitted with a [[flywheel]] having a {{convert|9|ft|m|adj=on}} diameter and weighing 9 tons, and was governed to a speed of 30 rpm. The engine became redundant when the rest of the system was modernised in 1974 and was donated to the [[Forncett Industrial Steam Museum]] by the [[City of London Corporation]].<ref name="Forncett">{{cite web |title=The Tower Bridge Engine |publisher=Forncett Industrial Steam Museum |url=http://oldenginehouse.users.btopenworld.com/towerb.htm |access-date=27 February 2007 |url-status=dead |archive-url=https://web.archive.org/web/20100225024729/http://oldenginehouse.users.btopenworld.com/towerb.htm |archive-date=25 February 2010 }}</ref>

The southern section of the bridge, in the [[London Borough of Southwark]], was [[Grade I listed]] on 6 December 1949.<ref>{{NHLE |num=1385980 |desc=Tower Bridge (that part that lies within the Borough of Southwark) |access-date=24 October 2019 |fewer-links=yes }}</ref> The remainder of the bridge, in the [[London Borough of Tower Hamlets]], was listed on 27 September 1973.<ref>{{NHLE|num=1357515|desc=Tower Bridge (that part that lies within the London Borough of Tower Hamlets|access-date=24 October 2019|fewer-links=yes }}</ref>

On 30 December 1952, a number 78 double-decker bus was crossing Tower Bridge. The process of stopping traffic when the bridge was getting raised failed while a relief watchman was on duty.
The bus was near the edge of the south bascule when it started to rise. Driver [[Albert Gunter|Albert Edward Gunter]] (1906–1968) made a split-second decision to accelerate the bus, clearing a 1.8 m (6 ft) drop onto the north bascule, which had not started to rise. The conductor broke his leg and twelve of the twenty passengers aboard received minor injuries. The driver was later rewarded with a £10 bonus (about £246.81 in 2025) for his quick thinking.<ref>{{Cite web|url=https://time.com/vault/issue/1953-01-12/page/31/|title=The TIME Vault: January 12, 1953}}</ref><ref>{{Cite web|url=https://www.bbc.co.uk/news/articles/cn7m8dmkglxo|title=The man who 'jumped' a double-decker bus over Tower Bridge's gap|date=30 December 2024|website=BBC News}}</ref>

In 1960, the upper bridges of the two pedestrian walkways that connected the two main towers were converted from being [[cantilever bridge]]s, projecting horizontally out into space, to [[suspension bridge]]s when suspension cables were added. This was to reinforce the strength of the walkways.<ref>{{Cite web |title=What type of bridge is Tower Bridge? |url=https://www.towerbridge.org.uk/discover/what-type-of-bridge-is-tower-bridge |access-date=14 May 2024 |website=Tower Bridge |language=en |archive-date=14 May 2024 |archive-url=https://web.archive.org/web/20240514131526/https://www.towerbridge.org.uk/discover/what-type-of-bridge-is-tower-bridge |url-status=live }}</ref>

In 1974, the original operating mechanism was largely replaced by a new electro-hydraulic drive system, designed by Geoffrey Beresford Hartwell, of BHA Cromwell House, with the original final [[pinion]]s driven by modern [[hydraulic motor]]s.{{sfn|Weinreb|Hibbert|Keay|Keay|2008|p=923}}<ref>{{cite web |url=https://www.phoenixhydraulics.co.uk/Blog/londons-tower-bridge |title=London's Tower Bridge |work=Phoenix Hydraulics |access-date=24 October 2014 |archive-date=24 October 2019 |archive-url=https://web.archive.org/web/20191024184056/https://www.phoenixhydraulics.co.uk/Blog/londons-tower-bridge |url-status=live }}</ref>

In 1982, the Tower Bridge Exhibition opened, housed in the bridge's twin towers, the long-closed high-level walkways, and the Victorian engine rooms. The latter still houses the original steam engines and some of the original [[hydraulic machinery]].<ref name=gbhmod>{{cite web |url=http://www.arbitrator-engineer-gbh.co.uk/#!firm/c1n8o |title=The Firm: BHA Cromwell House |publisher=G. M. Beresford Hartwell |access-date=30 June 2015 |archive-date=19 August 2015 |archive-url=https://web.archive.org/web/20150819105646/http://www.arbitrator-engineer-gbh.co.uk/#!firm/c1n8o |url-status=live }}</ref><ref name=hartwell>{{cite web |last=Hartwell |first=Geoffrey |title=Tower Bridge, London |url=http://www.hartwell.pwp.blueyonder.co.uk/tbpic.htm |archive-url=https://web.archive.org/web/20131208132600/http://www.hartwell.pwp.blueyonder.co.uk/tbpic.htm |url-status=dead |archive-date=8 December 2013 |access-date=27 February 2007 }}</ref><ref name="tbeabout">{{cite web |title=About Us |url=https://www.towerbridge.org.uk/about-us |url-status=live |archive-url=https://web.archive.org/web/20150706024544/http://www.towerbridge.org.uk/about/ |archive-date=6 July 2015 |access-date=8 April 2024 |website=Tower Bridge |publisher= }}</ref>