View source for Kap Shui Mun Bridge

{{Short description|Overpass in western Hong Kong}}
{{Infobox bridge
|bridge_name= Kap Shui Mun Bridge<br>汲水門大橋
|image=Kap Shui Mun Bridge from Sham Tseng.JPG
|caption=Kap Shui Mun Bridge, with Ma Wan in the foreground
|official_name= 
|also_known_as= KSMB
|carries= 6 lanes of roadway (upper)<br>2 [[MTR]] rail lines, 2 lanes of roadway (lower)
|crosses= [[Kap Shui Mun]]
|locale= [[Lantau Island|Lantau]] and [[Ma Wan]]
|maint= Tsing Ma Management Limited: operation and maintenance contractor for the [[Tsing Ma Control Area]]; under contract to the [[Highways Department]] of the [[Government of Hong Kong]]<ref name="factsheet">[http://www.gov.hk/en/about/abouthk/factsheets/docs/transport.pdf Hong Kong Factsheet: Transport]</ref>
|id= 
|design= Double-decked [[cable-stayed bridge]]
|mainspan= {{convert|430|m|ft}}
|length= {{convert|750|m|ft}}
|width= {{convert|32.5|m|ft}}
|clearance= 
|below= {{convert|47|m|ft}}
|traffic= 
|open= {{Start date and age|df=yes|1997|5|22}}
|closed= 
|toll= No (Since 27 December 2020)
|map_cue= 
|map_image= 
|map_text= 
|map_width= 
|coordinates= 
|lat= 
|long= 
}}
{{Chinese|pic=Bridges of Hong Kong harbor4.jpg|piccap=Kap Shui Mun Bridge|t=汲水門大橋|s=汲水门大桥|p=Jíshuǐmén Dàqiáo|y=kap<sup>1</sup> seui<sup>2</sup> mun<sup>4</sup> daai<sup>6</sup> kiu<sup>4</sup>}}
[[File:HK Lantau Bridges.jpg|thumb|Kap Shui Mun Bridge]]
The '''Kap Shui Mun Bridge''' (KSMB) in Hong Kong, part of [[Lantau Link]] of [[Route 8 (Hong Kong)|Route 8]], is one of the longest [[cable-stayed bridge]]s in the world that transports both road and railway traffic, with the upper deck used for motor vehicles and the lower deck for both vehicles and the [[MTR]]. It has a main span of {{convert|430|m|ft}} and an overall length of {{convert|750|m|ft}}. It spans the [[Kap Shui Mun]] marine channel between [[Ma Wan]] and [[Lantau Island|Lantau]] islands and has a vertical clearance of {{convert|47|m|ft}} above [[sea level]]. The bridge was completed in 1997.

== Structural information ==

<!-- Unsourced image removed: [[Image:Kap Shui Mun Bridge1.jpg|thumb|right|300px]] -->
{| class="wikitable" style="font-size:90%;"
| '''Main span'''
| {{convert|430|m|ft|abbr = on}}
|-
| '''Side spans'''
| Two {{convert|80|m|ft|abbr = on}} spans each side
|-
| '''Lantau Approach Span'''
| {{convert|70|m|ft|abbr = on}}
|-
| '''Ma Wan Viaduct'''
| {{convert|503|m|ft|abbr = on}}
|-
| '''Overall length'''
| {{convert|1323|m|ft|abbr = on}}
|-
| '''Height of towers'''
| {{convert|150|m|ft|abbr = on}}
|-
| '''Navigation clearance'''
| {{convert|47|m|ft|abbr = on}}
|}

The total length of the Kap Shui Mun Bridge includes a {{convert|70|m|ft|adj = on}} approach span on the Lantau side. There is a column in each of the back spans of the cable stayed bridge, making four {{convert|80|m|ft|adj = on}} spans, adding to the {{convert|430|m|ft|adj = on}} main span. This makes the total length {{convert|820|m|ft}}. The {{convert|503|m|ft|adj = on}} [[Ma Wan Viaduct]] was constructed under the same contract as the KSMB. The viaduct connects the KSMB to the [[Tsing Ma Bridge]], forming the Lantau Link, which was built to provide access to the new airport.<ref>{{cite web | last = Highways Department of the Government of the [[Hong Kong Special Administrative Region]] | title = Lantau Link project page | url = http://www.hyd.gov.hk/eng/major/airport/mw_f.htm | access-date = 2007-06-16 | url-status = dead | archive-url = https://web.archive.org/web/20070417023101/http://www.hyd.gov.hk/eng/major/airport/mw_f.htm | archive-date = 2007-04-17 }}</ref> The navigation clearance of {{convert|47|m|ft}} is part of the reason that the H-shaped towers are {{convert|150|m|ft}} tall.

The Kap Shui Mun Bridge is not symmetrical, in that the {{convert|160|m|ft|adj = on}} back span length (two {{convert|80|m|ft|adj = on}} spans) is less than half of the main span length (which would be {{convert|215|m|ft}}). To provide the balance that symmetry will normally provide, part of the bridge has a composite structure. The center {{convert|387|m|ft}} of the main span uses a steel-concrete composite to make the structure lighter. The back spans and the rest of the main span are concrete. Using the lighter steel cross section in the majority of the main span serves to equalize the horizontal forces on the towers and balance the bridge.<ref name="LAP">{{cite web | last = Leonhardt, Andrä und Partner, Consulting Engineers VBI, GmbH | title = Kap Shui Mun Bridge project page | url = http://www.lap-consult.com/english/e_projekt.php?sp=00024&kat=_03 | access-date = 2007-06-16 | url-status = dead | archive-url = https://web.archive.org/web/20070928003612/http://www.lap-consult.com/english/e_projekt.php?sp=00024&kat=_03 | archive-date = 2007-09-28 }}</ref>

Because the lower deck carries both rail and traffic, the cross section is designed as a [[Truss#Vierendeel truss|Vierendeel truss]]. This means that there are no diagonal members in the cross section and that vehicles and rail cars drive through the openings provided by the Vierendeel design.<ref name="LAP"/>

Along with the [[Tsing Ma Bridge]] and [[Ting Kau Bridge]], it is closely monitored by the [[Wind and Structural Health Monitoring System]] (WASHMS).

{| class="wikitable" style="font-size:90%;"
!colspan=2|Stay cables
|-
| '''Number'''
| 8 X 22 = 176
|-
| '''Total length of stay cables'''
| {{convert|11|km|mi|abbr = on}} 
|}

{| class="wikitable" style="font-size:90%;"
!colspan=2|Movement
|-
| '''Vertical, at midspan'''
| {{convert|470|mm|in|abbr = on}}
|-
| '''Lateral, at midspan'''
| {{Convert|155|mm|in|abbr = on}}
|-
| '''Longitudinal, at Pier 1'''
| {{convert|320|mm|in|abbr = on}}
|}

Concrete strength of towers: Grade 50/20 or 50MPa{{clarify|date=July 2014}}

==Crane strike==
The bridge has a height restriction of 41 metres for vessels passing underneath. On 23 October 2015, a barge attempted to pass under the bridge with a broken-down crane that could not be lowered. The crane had a maximum height of 43 metres, but was tilted slightly to 41 metres. The bridge has an actual clearance of 47 metres, but potentially due to the high tide and wave action, the crane struck the bridge and damaged its underside.<ref name=scmp27oct>{{cite news|last1=Lo|first1=Clifford|last2=Lai|first2=Ying-kit|title=Hong Kong airport bridge collision: Tug captain 'may have ignored height limit'|url=http://www.scmp.com/news/hong-kong/law-crime/article/1872595/hong-kong-airport-bridge-collision-tug-captain-may-have|work=South China Morning Post|date=27 October 2015}}</ref> The Tsing Ma Bridge has a higher height clearance of 53 metres but a source said the captain of the tugboat towing the barge may have opted to take Kap Shui Mun to save time.<ref name=scmp27oct/>

The strike triggered the Ship Impact Detection System to issue an alarm and both the road and railway were shut down immediately, severing Lantau Island and the airport from the city from about 7:40 pm to 10:00 pm.<ref name=ejinsight/> The government's contingency plan to implement emergency ferry service between Tsuen Wan and Tung Chung failed as the ferry operator took almost two hours to ready the service.<ref name=ejinsight>{{cite news|last1=Yeung|first1=SC|title=Lantau Link traffic chaos: What are the lessons?|url=http://www.ejinsight.com/20151026-lessons-from-lantau-link-traffic-chaos/|work=Hong Kong Economic Journal|date=26 October 2015}}</ref> Some travelers attempted to reach the airport via the [[Discovery Bay Ferry Pier]], although many missed their flights.

The [[Highways Department]] inspected the bridge and found that only the inspection platform rails were damaged by the collision, and that the structural integrity of the bridge was not jeopardised.<ref>{{cite news|title=Highways Department completes the inspection of Kap Shui Mun Bridge|url=http://www.info.gov.hk/gia/general/201510/24/P201510240813.htm|work=Hong Kong Government|date=24 October 2015}}</ref> In the days following the incident there were calls in local media for the government to build a second link to the airport. In fact, such a link was already under construction: the [[Tuen Mun–Chek Lap Kok Link]] road tunnel was being constructed as part of the [[Hong Kong–Zhuhai–Macau Bridge]] project. This opened in 2020.

==See also==
* [[List of tunnels and bridges in Hong Kong]]

==References==
{{reflist}}

==External links==
{{Commons category|Kap Shui Mun Bridge}}
* {{Structurae|id=20000039|title=Kap Shui Mun Bridge}}
* [https://web.archive.org/web/20071009032803/http://www.yokogawa-bridge.co.jp/english/products/pro07.html Yokogawa Bridge project page]

{{Coord|22|20|39.3|N|114|3|19.3|E|display=title|type:landmark}}
{{sequence
|prev=[[Ma Wan Viaduct]]
|list=[[Route 8 (Hong Kong)|Hong Kong Route 8]]<br>[[Image:HK Route8.svg|x20px]]<br>Kap Shui Mun Bridge
|next=[[North Lantau Highway]]
}}
{{Bridges in Hong Kong}}
{{HK routes|r8;}}
{{NTTaxi}}

[[Category:Bridges completed in 1997]]
[[Category:Double-decker bridges]]
[[Category:Bridges in Hong Kong]]
[[Category:Route 8 (Hong Kong)]]
[[Category:Road-rail bridges]]
[[Category:Railway bridges in Hong Kong]]
[[Category:Cable-stayed bridges in Hong Kong]]
[[Category:Tsuen Wan District]]
[[Category:Vierendeel truss bridges]]