Editing Hanwell (section)

===The Wharncliffe Viaduct===
{{main|Wharncliffe Viaduct}}Brunel's first major structural design and the first contract to be let on his Great Western Railway. The viaduct carries trains across the Brent valley at an elevation of {{convert|65|ft|m}}.<ref>{{Cite journal|year=2018|title=Wharncliffe Viaduct|url=http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=444|journal=Engineering Timelines|access-date=26 December 2018|archive-date=11 July 2007|archive-url=https://web.archive.org/web/20070711072721/http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=444|url-status=live}}</ref>

Constructed of brick, the {{convert|900|ft|m|adj=mid|-long}} bridge has 8 arches, each spanning {{convert|70|ft|m}} and rising {{convert|17|ft|6|in|m}}.<ref>{{Cite web|url=http://www.victorianweb.org/technology/bridges/43.html|title=Wharncliffe Viaduct, Greater London|website=victorianweb.org|access-date=26 December 2018|archive-date=20 June 2019|archive-url=https://web.archive.org/web/20190620200410/http://www.victorianweb.org/technology/bridges/43.html|url-status=live}}</ref> The supporting piers are hollow and tapered, rising to projecting stone cornices that held up the arch centring during construction.

Originally, the piers were {{convert|30|ft|m}} wide at ground level and {{convert|33|ft|m}} at deck level. The deck was designed to accommodate two tracks of Brunel's broad gauge railway.

However, an [[Regulating the Gauge of Railways Act 1846|Act of Parliament]] was passed in 1846 that made Stephenson's narrower gauge standard across the country and so the viaduct was widened in 1847 by the addition of an extra row of piers and arches on the north side. The new width is {{convert|55|ft|m}}. In 1892 the broad gauge track was converted to standard gauge, and this allowed enough width for four standard gauge tracks. Overhead electrification, at 25,000 volts AC, of the London to Bristol main line is in progress (2017).

The viaduct is still used today for trains running from Paddington to Bristol. Lord Wharncliffe's coat of arms can be seen on the central pier on the south side. He was chairman of the Great Western Railway.<ref>{{Cite web|title=GREAT WESTERN RAILWAY. (Hansard, 27 August 1835)|url=https://api.parliament.uk/historic-hansard/lords/1835/aug/27/great-western-railway|access-date=2021-07-28|website=api.parliament.uk}}</ref>