Editing Sydney Harbour Bridge (section)

==Structure==
[[File:Sydney Harbour Bridge from the air.JPG|thumb|Sydney Harbour from the north-east with the [[Sydney Opera House|Opera House]], [[Sydney central business district|CBD]], [[Circular Quay]], the Bridge, the [[Parramatta River]], [[North Sydney, New South Wales|North Sydney]] and [[Kirribilli]] in the foreground|left]]
The southern end of the bridge is located at [[Dawes Point]] in [[The Rocks, New South Wales|The Rocks]] area, and the northern end at [[Milsons Point]] on the lower [[North Shore (Sydney)|North Shore]]. There are six original lanes of road traffic through the main roadway, plus an additional two lanes of road traffic on its eastern side, using lanes that were formerly [[Trams in Sydney|tram tracks]]. Adjacent to the road traffic, a path for pedestrian use runs along the eastern side of the bridge, whilst a [[Sydney Harbour Bridge cycleway|dedicated path for bicycle use]] runs along the western side. Between the main roadway and the western bicycle path lies the [[North Shore railway line]].

The main roadway across the bridge is known as the [[Bradfield Highway, Sydney|Bradfield Highway]] and is about {{Convert|2.4|km|mi|1|abbr=on}} long, making it one of the shortest highways in Australia.<ref>{{cite web|url=http://factsforkids.net/sydney-harbour-bridge-facts-kids/|title=Sydney Harbour Bridge Facts for Kids|date=12 May 2016|website=Facts For Kids|access-date=27 December 2018|archive-url=https://web.archive.org/web/20181227085405/http://factsforkids.net/sydney-harbour-bridge-facts-kids/|archive-date=27 December 2018|url-status=live}}</ref>

===Arch===
[[File:Sydney Harbour Bridge from Circular Quay.jpg|left|thumb|The bridge illuminated at night]]
The arch is composed of two 28-panel arch trusses; their heights vary from {{Convert|18|m|ft|0|abbr=on}} at the centre of the arch, to {{Convert|57|m|ft|0|abbr=on}} at the ends next to the pylons.<ref>{{cite web|title=Sydney Bridge Information|url=http://www.sydneyharbourbridge.com.au/|date=October 2016|access-date=15 October 2016|archive-url=https://web.archive.org/web/20161003061447/http://sydneyharbourbridge.com.au/|archive-date=3 October 2016|url-status=live}}</ref>

The arch has a span of {{convert|504|m|ft|0|abbr=on}}, and its summit is {{Convert|134|m|ft|0|abbr=on}} above mean sea level; expansion of the steel structure on hot days can increase the height of the arch by {{Convert|18|cm|in|1|abbr=on}}.<ref>{{cite web|url=http://www.skwirk.com/p-c_s-14_u-309_t-763_c-2866/the-construction-of-the-sydney-harbour-bridge/nsw/history/investigating-history/take-a-good-look|title=The construction of the Sydney Harbour Bridge|work=Year 9 NSW//History//Investigating History|publisher=Red Apple Education|year=2008|access-date=27 May 2008|archive-url=https://web.archive.org/web/20110310163739/http://www.skwirk.com/p-c_s-14_u-309_t-763_c-2866/the-construction-of-the-sydney-harbour-bridge/nsw/history/investigating-history/take-a-good-look|archive-date=10 March 2011|url-status=live}}</ref> [[File:SydneyHarbourBridgeNutMilsonsPoint.JPG|thumb|One of the nuts that hold the bridge on its abutments; this one is at the north end.|left]]The total weight of the steelwork of the bridge, including the arch and approach spans, is {{convert|52800|t}}, with the arch itself weighing {{convert|39000|t}}.<ref name="pl-bf">{{cite web|title=Bridge Facts|url=http://www.pylonlookout.com.au/history_frs.htm|work=Pylon Lookout: Sydney Harbour Bridge|access-date=17 December 2010|archive-url=https://web.archive.org/web/20110218075104/http://www.pylonlookout.com.au/history_frs.htm|archive-date=18 February 2011|url-status=live}}</ref> About 79% of the steel, specifically those technical sections constituting the curve of the arch, was imported pre-formed from England, with the rest being sourced from the [[Newcastle Steelworks]].<ref name="pl-bh" /> On site, Dorman Long & Co set up two workshops at Milsons Point, at the site of the present-day [[Luna Park Sydney|Luna Park]], and fabricated the steel into the [[girder]]s and other required parts.<ref name="pl-bh" />

The bridge is held together by six million Australian-made hand-driven rivets supplied by the McPherson company of Melbourne,<ref>{{cite book|title=Sydney Harbour Bridge|publisher=[[Dorman Long|Dorman, Long & Co]]|page=13|year=1932}}</ref><ref>{{cite book|title=Bridging Sydney|editor=C. Mackaness|publisher=[[Historic Houses Trust of New South Wales]]|year=2007}}</ref> the last being driven through the deck on 21 January 1932.<ref name="pl-bh">{{cite web|title=Bridge History|url=http://www.pylonlookout.com.au/history_frs.htm|work=Pylon Lookout: Sydney Harbour Bridge|access-date=17 December 2010|archive-url=https://web.archive.org/web/20110218075104/http://www.pylonlookout.com.au/history_frs.htm|archive-date=18 February 2011|url-status=live}}</ref><ref name="shb-info">{{cite web|title=Sydney Harbour Bridge Info|url=http://www.sydneyharbourbridge.info/|access-date=17 December 2010|archive-url=https://web.archive.org/web/20110412023915/http://www.sydneyharbourbridge.info/|archive-date=12 April 2011|url-status=live}}</ref> The rivets were heated red-hot and inserted into the plates; the headless end was immediately rounded over with a large [[pneumatic]] [[rivet gun]].<ref name="bos-rivets">{{cite web|title=Engineering Materials: Rivets|url=http://sydney-harbour-bridge.bos.nsw.edu.au/engineering-studies/rivets.php|work=Sydney Harbour Bridge|publisher=NSW Government: Board of Studies|access-date=17 December 2010|archive-url=https://web.archive.org/web/20110221164703/http://sydney-harbour-bridge.bos.nsw.edu.au/engineering-studies/rivets.php|archive-date=21 February 2011|url-status=live}}</ref> The largest of the rivets used weighed {{Convert|3.5|kg|lb|0|abbr=on}} and was {{Convert|39.5|cm|in|1|abbr=on}} long.<ref name="pl-bf" /><ref name="tia-shb">{{cite web|title=The Sydney Harbour Bridge |url=http://australianstory.net.au/TIA/node/7 |work=This is Australia.com.au |access-date=17 December 2010 |url-status=dead |archive-url=https://web.archive.org/web/20091015145242/http://australianstory.net.au/TIA/node/7 |archive-date=15 October 2009 }}</ref> The practice of riveting large steel structures, rather than welding, was, at the time, a proven and understood construction technique, whilst structural welding had not at that stage been adequately developed for use on the bridge.<ref name="bos-rivets" />

===Pylons===
[[File:Sydney Harbour Bridge SE Pylon, jjron, 02.12.2010.jpg|upright|thumb|The south-eastern pylon containing the tourist lookout, made of [[granite]] quarried at [[Moruya]]]]
At each end of the arch stands a pair of {{Convert|89|m|ft|0|adj=mid|-high}} concrete pylons, faced with [[granite]].<ref name="pl-ph22">{{cite web|title=South East Pylon History: 1922 – 1932|url=http://www.pylonlookout.com.au/history_frs.htm|work=Pylon Lookout: Sydney Harbour Bridge|access-date=18 December 2010|archive-url=https://web.archive.org/web/20110218075104/http://www.pylonlookout.com.au/history_frs.htm|archive-date=18 February 2011|url-status=live}}</ref> The pylons were designed by the Scottish architect [[Thomas S. Tait]],<ref name="tait1">{{cite book|last=Smiles|first=Sam|title=Going modern and being British: 1910–1960|publisher=Intellect Books|year=1998|page=41|isbn=978-1-871516-95-1}}</ref> a partner in the architectural firm John Burnet & Partners.<ref name="glasgowsculpture">{{cite web|url=http://glasgowsculpture.com/pg_biography.php?sub=burnet_j-son|title=John Burnet & Son|last=Nisbet|first=Gary|work=Glasgow – City of Sculpture|access-date=14 November 2008|archive-url=https://web.archive.org/web/20081207182850/http://glasgowsculpture.com/pg_biography.php?sub=burnet_j-son|archive-date=7 December 2008|url-status=live}}</ref>

Some 250 Australian, Scottish, and Italian [[stonemason]]s and their families relocated to a temporary settlement at [[Moruya]], {{Convert|300|km|mi|0|abbr=on}} south of Sydney, where they [[Quarry|quarried]] around {{Convert|18000|m3|ft3|0|abbr=on}} of granite for the bridge pylons.<ref name=pl-bh /> The stonemasons cut, dressed, and numbered the blocks, which were then transported to Sydney on three ships built specifically for this purpose. The Moruya quarry was managed by John Gilmore, a Scottish stonemason who emigrated with his young family to Australia in 1924, at the request of the project managers.<ref name=pl-bh /><ref>{{cite journal|journal=Inside History Magazine|title=To make a bridge. Where did the granite of the Sydney Harbour Bridge come from?|date=19 April 2014|url=http://www.insidehistory.com.au/2014/04/tae-mak-a-brig-to-make-a-bridge-where-did-the-granite-of-the-sydney-harbour-bridge-come-from/|archive-url=https://web.archive.org/web/20170331030121/http://www.insidehistory.com.au/2014/04/tae-mak-a-brig-to-make-a-bridge-where-did-the-granite-of-the-sydney-harbour-bridge-come-from/|archive-date=31 March 2017|url-status=dead|access-date=12 April 2019}}</ref><ref>{{cite web|url=http://www.granitetown.com.au/moruyahistory/|title=Moruya History|archive-url=https://web.archive.org/web/20180311000310/http://www.granitetown.com.au/moruyahistory/|archive-date=11 March 2018|url-status=dead|access-date=12 April 2019}}</ref> The concrete used was also Australian-made and supplied from [[Kandos]].<ref>{{cite web|url=http://nla.gov.au/nla.news-article28034379|title=Kandos Cement|publisher=[[Sydney Morning Herald]]|date=19 March 1932|access-date=8 October 2018|archive-date=24 September 2023|archive-url=https://web.archive.org/web/20230924095437/https://trove.nla.gov.au/newspaper/article/28034379|url-status=live}}</ref><ref>{{cite web|url=http://nla.gov.au/nla.news-article219676124|title=Cement and the Bridge Part Played by Kandos Co|publisher=[[Lithgow Mercury]]|date=7 March 1932|access-date=8 October 2018|archive-date=24 September 2023|archive-url=https://web.archive.org/web/20230924095438/https://trove.nla.gov.au/newspaper/article/219676124|url-status=live}}</ref><ref>{{cite web|url=http://nla.gov.au/nla.news-article156201488|title=Stands the Test Kandos Cement Used for Harbour Bridge|publisher=Mudgee Guardian|date=19 May 1930|website=Trove|access-date=8 October 2018|archive-date=24 September 2023|archive-url=https://web.archive.org/web/20230924095438/https://trove.nla.gov.au/newspaper/article/156201488|url-status=live}}</ref><ref>{{cite web|url=http://nla.gov.au/nla.news-article158296349|title=Kandos a Great Industry|publisher=[[The Sydney Mail]]|date=7 September 1927|access-date=8 October 2018|archive-date=24 September 2023|archive-url=https://web.archive.org/web/20230924095436/https://trove.nla.gov.au/newspaper/article/158296349|url-status=live}}</ref>

[[Abutment]]s at the base of the pylons are essential to support the loads from the arch and hold its span firmly in place, but the pylons themselves have no structural purpose. They were included to provide a frame for the arch panels and to give better visual balance to the bridge. The pylons were not part of the original design, and were only added to allay public concern about the structural integrity of the bridge.<ref>{{cite book|last=Lalor|first=Peter|title=The bridge|page=142|publisher=[[Allen & Unwin]]|orig-year=2005|year=2006|isbn=978-1-74175-027-0}}</ref>

Although originally added to the bridge solely for their aesthetic value, all four pylons have now been put to use. The south-eastern pylon contains a museum and tourist centre, with a 360° lookout at the top providing views across the Harbour and city. The south-western pylon is used by [[Transport for NSW]] to support its [[Closed-circuit television|CCTV]] cameras overlooking the bridge and the roads around that area. The two pylons on the north shore include venting chimneys for fumes from the [[Sydney Harbour Tunnel]], with the base of the southern pylon containing the Transport for NSW maintenance shed for the bridge, and the base of the northern pylon containing the traffic management shed for tow trucks and safety vehicles used on the bridge.

In 1942, the pylons were modified to include parapets and anti-aircraft guns designed to assist in both Australia's defence and general war effort.<ref>{{cite web|title=1942–1945 (WWII)|url=http://www.pylonlookout.com.au/PylonLookoutMediaKit.pdf|work=The Pylon Lookout|year=2004|access-date=24 January 2018|archive-url=https://web.archive.org/web/20180314082136/http://www.pylonlookout.com.au/PylonLookoutMediaKit.pdf|archive-date=14 March 2018|url-status=live}}</ref>