Editing Richmond Lock and Footbridge (section)

==Description==
The chief engineer who designed the core of the structure, [[Francis Goold Morony Stoney|F. G. M. Stoney]], took out seven patents relating to sluices between 1873 and 1894.<ref name=listing/> Hunt and Steward, surveyors, designed the lockhouses.<ref name=listing/> [[Ransomes & Rapier]] of [[Ipswich]] designed the ironwork including the arches.<ref name=listing/> The structure was built between 1891 and 1894.

;The structures
The superstructure was built horizontally in three sections, the middle section forms the bulk and has, itself, three [[span (architecture)|spans]].

The lock is the first section, topped by the first of five ornate metal arches which spread over the other sections. The middle section has mechanically rising-to-parapet-height sluice gates forming sheets of metals above and close to the water line which is created by these structures when lowered. The final section is a set of two facing ramps in part with canoe/boat rollers.

;Purpose
The lock and barrages were installed in 1894 by the [[Thames Conservancy]] to maintain a broad navigable depth of water upstream of Richmond. The rising barrage ensures upstream at least {{convert|1.72|m}} of water is in the standard navigation channel (away from banks) to the next lock, Teddington, and an annual draw-off (an all-tides lifting of the sluice gates) takes place to enable [[dredging]] to keep the advertised {{convert|1.72|m}} minimum channel depth.<ref>{{cite web | url = http://www.the-river-thames.co.uk/locks2.htm | title = ''The River Thames – Lock Details'' | publisher = www.the-river-thames.co.uk | access-date = 31 October 2007}}</ref><ref>{{cite web | url = http://www.portoflondon.co.uk/display_fixedpage.cfm/id/2253 | title = ''Richmond Lock and Weir'' | publisher = Port of London Authority | access-date = 2007-10-31}}</ref><ref>{{cite web | url = http://www.victorianweb.org/technology/canals/7.html | title = ''Lock Mechanism, Richmond Lock, London'' | publisher = The Victorian Web | access-date = 17 September 2021}}</ref><ref>{{cite web | url = http://www.cl.cam.ac.uk/~chn2/photos/richmondlock03/ | title = ''Richmond Lock 2003'' | publisher = Christine Northeast | access-date = 31 October 2007}}</ref>

===Ownership and operation===
The [[Port of London Act 1908]] ([[8 Edw. 7]]. c. 68) transferred responsibility for all points of the river downstream of a point {{convert|350|yd|m}} below [[Teddington Lock]] to the [[Port of London Authority]] thereby including this structure.<ref>Thacker, Fred S. ''The Thames Highway: Volume 1 General History'' David & Charles 1968</ref>

===Reasons for construction{{anchor|Richmond Footbridge Sluices, Lock and Slipway Act 1890}}===
{{Infobox UK legislation
| short_title           = Richmond Footbridge Sluices, Lock and Slipway Act 1890
| type                  = Act
| parliament            = Parliament of the United Kingdom
| long_title            = An Act to authorise the construction of a Footbridge with removable Sluices and a Lock and Slipway on the River Thames in the parishes of Richmond and Isleworth and for other purposes.
| year                  = 1890
| citation              = [[53 & 54 Vict.]] c. ccxxiv
| introduced_commons    = 
| introduced_lords      = 
| territorial_extent    = 
| royal_assent          = 14 August 1890
| commencement          = 
| expiry_date           = 
| repeal_date           = 
| amends                = 
| replaces              = 
| amendments            = 
| repealing_legislation = [[Port of London Act 1968]]
| related_legislation   = 
| status                = repealed
| legislation_history   = 
| theyworkforyou        = 
| millbankhansard       = 
| original_text         = https://www.legislation.gov.uk/ukla/Vict/53-54/224/pdfs/ukla_18900224_en.pdf
| revised_text          = 
| use_new_UK-LEG        = 
| UK-LEG_title          = 
| collapsed             = yes
}}
When the [[London Bridge#"Old" London Bridge (1209–1831)|London Bridge of 1209 to 1831]] was demolished the removal of its bulky and elaborate piers resulted in the tides upstream returning to the rapid flows as they were downstream and before its forming of a near-barrier. That bridge was particularly [[dam]]-like when it housed 200 buildings in the Tudor period and in depictions at the time of the [[Great Fire of London]] which spared the bridge. This change, together with dredging of the lower river (lowest reaches) and construction of Teddington Lock and weir, meant that for hours of each day the Thames at Richmond, Twickenham, Ham, Petersham and northern Teddington, was a shallow watercourse running past great mud and shingle banks. The exception was after weeks of above-average rainfall when the river is known as ''in spate'' however such outflow hinders navigation upstream.<ref>{{Cite web |url=http://www.pla.co.uk/assets/m51of2017-richmondlockweirdrawoff2017-weirsopen29thoctoberto19thnovember.pdf |title=Richmond Lock and weir draw-off 2017 |publisher = [[Port of London Authority]] |date = 1 June 2017|access-date = 30 April 2020}}</ref><!--See draw-off navigation advice, Port of London Authority, what is the draw off?-->  By the late 19th century water extraction above Teddington had increased to [[London water supply infrastructure#Water Treatment Works|four of five of the city's main waterworks]] and after light or normal rainfall more barges found it impossible to navigate the reach during and for hours around the two low tides each day.  In 1890, after many years of petitioning, an act of Parliament was enacted to build the half-lock and weir, the '''Richmond Footbridge Sluices, Lock and Slipway Act 1890''' ([[53 & 54 Vict.]] c. ccxxiv). This is among a small minority of Thames locks not to have been built around an island or islands (aits).

[[File:RichmondFootbridge.jpg|thumb|Richmond Footbridge]]

===Details of design===
{{Annotated image
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| caption = Detail of arches showing thousands of bricks at core of tall, great piers and forming most of the structure 
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A barge lock was constructed against the north-east ("[[Surrey]]") side. This is followed by four immense brick [[pier (architecture)|piers]] protected by large [[ashlar]] stone [[cutwater]]s (starlings). These in turn support relatively thin stone [[Ashlar|dressings]] reaching to the metal parapet level, carved in a classical style with [[reredo]]s and [[cornice]]s, supporting painted metal arches. A matching-colour [[balustrade]] is above the arches finished with black lanterns, metal pillars and simple [[finial]]s. The piers house the barriers and the arches support a pair of horizontal [[deck (bridge)|decks]] (walkways). Against the opposite bank is a gently elevated slipway accessed from upstream and downstream parts of the river. As a superstructure was required to hold the suspended barriers, authorities agreed to build this in the form of two footbridges.<ref>{{cite web | url = http://www.touruk.co.uk/london_bridges/richmond_lock1.htm | title = Richmond Lock | work = London Bridges|publisher = Just Tour Limited | access-date = 30 April 2020 | url-status = dead | archive-url = https://web.archive.org/web/20070927065954/http://www.touruk.co.uk/london_bridges/richmond_lock1.htm | archive-date = 27 September 2007 | df = dmy-all }}</ref><ref>{{cite web | url = http://www.pbase.com/john_cooper/richmond_footbridge | title = Richmond Footbridge | author=  Cooper, John | website = PBase.com|access-date = 30 April 2020}}</ref>
The bridge was formally opened on 19 May 1894 by the then Duke of York (who later became King [[George V of the United Kingdom|George V]]), having cost £61,000 ({{Inflation|UK|61,000|1892|r=-5|fmt=eq|cursign=£}}).<ref name=listing/>

Richmond Lock is a half-tide lock and (half-tide) barrage which incorporates a public footbridge. The footbridge crosses the conventional lock, the barrages and the slipway, which comprises three vertical steel sluice gates suspended from the footbridge structure. Each sluice gate weighs 32 tons, is {{convert|66|ft}} in width and {{convert|12|ft}} in depth. The lock permits passage of vessels up to {{convert|250|feet}} long by 26 feet 8&nbsp;inches [[Beam (nautical)|wide]].

For about two hours each side of the published time of [[high tide]] the three sluice gates are raised into the footbridge supports above, and river traffic can pass through the barrage unimpeded. For the rest of the tidal cycle sluice gates are lowered – ships and boats must use the lock alongside the barrage at a cost of {{as of|2022|alt=£10 per boat}}. Rowing boats and kayaks can use the roller solid slipways which reach an apex above the height of the barrages. The maximum fall of the lock is {{convert|10|ft}}.