Koror – Babeldaob Bridge
Coordinates: 7 ° 21 ′ 44 ″ N , 134 ° 30 ′ 16 ″ E
| Koror – Babeldaob Bridge | |
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| Crossing of | Toachel Channel |
| place | Koror - Babeldaob |
| construction | Prestressed concrete bridge |
| overall length | 1.) 386 m 2.) 413 m |
| Number of openings | three |
| Longest span | 1.) 240.8 m 2.) 247 m |
| start of building | 1.) 1976 2.) 1999 |
| completion | 1.) 1977 2.) 2002 |
| Status | 1.) Collapsed on September 26, 1996 2.) In operation |
| planner | 1.) A. Yee and Associates; Dywidag , Man-Chung Tang 2.) Nippon Koei |
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The Koror – Babeldaob Bridge , also known as Japan – Palau Friendship Bridge or simply K – B Bridge , is a road bridge between the islands of Koror and Babeldaob in the island state of Palau in the Pacific .
Palau is located east of the Philippines , north of Indonesia or New Guinea and west of the island state of Micronesia . The island of Guam is located around 1300 km northeast of Palau. Until 1994, Palau was a UN trust territory under the control of the United States .
The island of Koror is the economic center of Palau with around 12,000 inhabitants, Babeldaob (also Babelthuap) is its largest island, on which the Roman Tmetuchl International Airport is also located. The bridge is the only permanent link between the two islands that also carries the drinking water and power lines for Koror. Between them lies the Toachel Canal, a canal that has been washed out by the current, is around 240 m wide and 30 m deep, between the shallow, now partially built-up coral waters off the shores of the islands.
First Bridge (1977)
For the tender for the first bridge, Alfred Yee & Associates, Honolulu , produced a design for a two-lane bridge with wide walkways. The subsequent survey of the construction site showed that the bridge would have to have a much wider opening in order not to stand in deep water.
The plan revised by Dyckerhoff & Widmann, Inc. then saw a 385.6 m (1265 ft ) long and 9.62 m wide prestressed concrete bridge according to the Dywidag system with a span of 240.8 m (790 ft) and 53.65 m wide side openings. It had a rectangular, single-cell, 7.32 m (24 ft) wide, haunched box girder , the height of which decreased from 13.87 m to the center of the field to 3.66 m and which had a joint in the center of the field.
This planning was carried out between May 1976 and April 1977 by a company from Guam, whereby the main field was erected in cantilever and the side fields, which only slightly protruded from the water , were erected on falsework . The short side panels were partially filled with stone material in order to counterbalance the cantilever arms above the main opening.
The bridge was the largest prestressed concrete bridge in the world when it opened, only to be surpassed by the Gateway Bridge in Brisbane , Australia in 1986 .
Over the next 19 years, the carriageway over the main opening gradually sank by up to 1.2 m. Expert opinions came to the conclusion that the bridge was still safe, but without being able to name the reason for the lowering. In 1996, a repair was carried out in accordance with VSL's specifications, during which the cantilever arms were pressed apart to their original position using hydraulic presses, the gap was filled with concrete and the structure was reinforced with external tendons, which became a continuous beam . The road was renewed with an asphalt surface.
The bridge collapsed on September 26, 1996 at 5:35 a.m., less than 3 months after repair.
Consequences of the collapse
One person died in the collapse and four people were slightly injured. The approximately 12,000 inhabitants of Koror were cut off from the water supply because there are no springs on the island. The sanitary facilities in the houses also no longer worked without water. The government of Palau, which had no significant funds of its own, declared a state of emergency and asked the US for help. The Red Cross organized the transport of water canisters from a spring in Babeldaob by boat and truck to Koror for an emergency supply of 10 liters per day per person. Further water supply equipment was flown by the Japanese Red Cross via Guam to Palau.
A ferry connection was established. In August 1997, a pontoon bridge supplied by Daiho Corporation was installed.
The collapse has been discussed in the specialist literature around the world without any generally accepted result. In part, this was due to the subsequent legal proceedings, in which the construction documents and detailed damage records were confidential and only became available to the professional world around 2013. But Man-Chung Tang does not come to a conclusive explanation in his work The Story of the Koror Bridge , published in 2014 .
Second bridge (2002)
Due to a Japanese aid program, the second bridge, designed by Nippon Koei, was built by Kajima Corporation between November 1999 and December 2001 after removing the rubble from the old bridge. The new bridge was officially opened on January 13, 2002.
The hybrid extradosed bridge is 412.7 m long and has three openings with pillar spacing of 82.0 + 247.0 + 82.0 m.
In order to reduce the imbalance between the long middle section and the relatively short side sections, the roadway panel has an 82.0 m long steel suspension beam in the middle of the field , to which are connected on both sides 2.5 m long transition elements and 162.7 m long prestressed concrete hollow box girders Tendons, similar to a cable-stayed bridge , are anchored to the deck and short pylons made of reinforced concrete. The suspension beam is a box girder that was towed from China to Palau on a barge and lifted to its final position directly by the barge at the construction site. The pylons stand on bored piles that were drilled through the piles of the old bridge.
literature
- Man-Chung Tang: The Story of the Koror Bridge . International Association for Bridge and Structural Engineering (IABSE), 2014, ISBN 978-3-85748-136-9 ( iabse.org [PDF; 8.4 MB ]).
Web links
Individual evidence
- ↑ Richard Heinen: Design-construction considerations for alternate systems; competitive bid encouragement . Koror-Babelthuap Bridge. In: Walter Podolny, Jr. (Ed.): Prestressed Concrete Segmental Bridges . Structural Engineering Series No. 9. US Department of Transportation; Federal Highway Administration, Washington, DC Aug 1979, pp. 139; Koror-Babelthuap Bridge p. 147 ( full text in the Google book search).
- ↑ a b Chris Burgoyne, Richard Scantlebury: Why did Palau Bridge collapse? In: The Structural Engineer, June 6, 2006, p. 30
- ↑ Leonardo Fernández Troyano: Bridge Engineering. A global perspective . Colegio de Ingenieros de Caminos, Canales y Puentes; Thomas Telford, London 2003, ISBN 0-7277-3215-3 , pp. 426 ( limited preview in Google Book search).
- ^ Republic of Palau. Koror – Babeldaup Bridge repair . In: VSL News , Issue 2, 1996
- ^ Matthias Pilz: Investigations into the collapse of the K – B bridge in Palau . In: Beton- und Stahlbetonbau , 94th year, issue 5, May 1999, pp. 229–232
- ^ Matthias Pilz: The Collapse of the K – B Bridge in 1996. A MSc dissertation at the Imperial College London. In: Leipzig Annual Civil Engineering Report (LACER) No. 2, Leipzig, 1997 (on wikiwix )
- ↑ Siman Missiri: Palau: Bridge collapse. Information Bulletin of October 1, 1996 on ifrc.org (PDF; 8.2 KB)
- ^ Palau pontoon bridge. In: Structurae
- ↑ Hisashi Oshima, Nobuyki Suzuki, Tomohiko Kashiwamura, Ichiro Oda: Design and construction of Japan Palau Friendship Bridge . In: Proceedings of the first fib Congress 2002 - Concrete Structures in the 21st Century . tape 1 . fédération internationale du béton (fib), 2002, p. 39 ( full text in Google Book Search).