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228 Taiwan Development Perspectives 2009 1. Introduction Typhoon Sinlaku hit Taiwan on September 14, 2008, leaving in its wake half a dozen people dead and a dozen bridges broken down. The people were killed as their cars plunged into the river when one of the bridges collapsed. As rivers began to overflow their banks during the typhoon, many bridges were closed to traffic. The closing for traffic safety, though brief, affected highway transportation. The Ministry of Transportation and Communications was blamed for failure to continue proper maintenance of bridges. As a matter of fact, there are many bridges that may collapse in floods triggered by tropical rainstorms. More government efforts are needed to ensure bridge safety across the country. 2. Causes of Collapses of Bridges On-site inspections found most bridge foundations were washed bare in floods touched off by the typhoon. The weakened foundations caused the bridges to collapse. Most of the bridges were built after Taiwan started its economic takeoff in the 1965. They were designed to withstand earthquakes, which hit Taiwan more often than typhoons. The bridge foundations were not designed to withstand flash floods, which are often more devastating than earthquakes. The Houli-Fengyuan Bridge was one of those bridges. Its foundations had eroded seriously before Sinlaku lashed central Taiwan. The bridge collapsed, sending cars crossing it into the river, in which all the people aboard them were drowned. It was built on the river plate where such hydraulic structures as a dam, weirs, and groundsill works had been constructed. These hydraulic structures had to be taken into consideration when the bridge was designed. The river flows rapidly from a mountain more than 3,000 meters above sea level to the sea less than 50 kilometers away, negotiating an extremely steep gradient. Soil erosion in the upstream of the river was just as serious. When torrential rains brought by the typhoon triggered floods, the bridge with its foundations eroded simply succumbed. All bridge superstructures were found safe. They were ruled out as the cause of collapses of bridges. Collapses will occur during typhoons only if bridge foundations are weak or weakened. Their foundations have to be strong enough to withstand earthquakes as well as flash floods caused by tropical rainstorms. 3. Reconstruction There are more than 26,000 bridges on Taiwan. Many of them are considered “dangerous,” for they may collapse in floods. These dangerous bridges have to be rebuilt and their reconstruction requires an outlay which cannot be made up by the fuel tax collection alone. Moreover, the revenue from taxation on fuel is used to maintain not just bridges but roads and tunnels as well. No tolls are collected for crossing most of the bridges in Taiwan. The government has to prepare enough budget appropriations for rebuilding the dangerous bridges. The majority of Taiwan’s bridges are simple support bridges and shorter span RC plate bridges with box caisson and/or pile foundations. Some of them were built in the 1950s when the standard of design was low and construction was technically poor. Moreover, dams and weirs built upstream have changed the equilibrium in sediment transport of rivers. The further erosion of river plates resulting from gravel-mining downstream has continued to weaken bridge foundations. Those bridges with their foundations seriously weakened have to be rebuilt. Reconstruction is needed: a. If bridges were destroyed or and washed away; b. If bridge foundations were washed bare or sank to cause the bridge floor to collapse and if there is no way to reinforce the weakened foundations with groundsill work to meet aseismatic prevention requirements; c. If bridges suffered damage in the past and their foundations were bared, while the reinforcement with
Reconstruction of Dangerous Bridges: An Urgent Need 229 groundsill work could not meet aseismatic prevention requirement; d. If bridges are found to suffer significant damage on parts of their major structure and their condition continues to deteriorate, while no reinforcement work is considered effective to prevent the deterioration; e. If bridges do not meet the requirements set forth in the River Management Project; f. If bridges are too old to meet the requirements stipulated in the Regulations Governing the Reviews of River-Crossing Structures, promulgated by the Ministry of Economic Affairs on June 12, 2006; and g. If local governments recommend the widening of the existing bridges to link up with widened roads and highways. 4. Government Projects The government is spending NT$25 billion (US$756 million) to rebuild dangerous bridges across the country. a. County old bridge improvement project: Eighteen bridges were to be built or improved upon between 1996 and 1998 under a special economic development program, which is scheduled for completion by 2015. Eight of them were built. Six others are under construction. Another three will be completed by the end of 2009. Construction of superstructures is under way for still another, the Gueishan Bridge. b. Improvement of dangerous bridges: The Executive Yuan approved construction and improvement of 188 bridges in March 2007. Altogether NT$1,528,490,000 has been budgeted for the project. Appropriations for 2008 totaled NT$581,540,000. Another NT$946,950,000 will be appropriated for 2009. Of the total outlay NT$1,320,640,000 comes from the Central Government. The local governments raise the remaining NT$278.5 million as a matching fund. Construction of 140 bridges was scheduled to be contracted in 2008. Contracts were signed for construction of 38 bridges. Only one bridge was built, though one more had to be completed by the end of 2008. c. Refurbishment of 40 provincial highway bridges: Forty provincial highway bridges are being refurbished. The total outlay is NT$12,964 million. Construction costs NT$12,802 million. The remaining NT$162 million is appropriated for land purchase. The Council for Economic Planning and Development raised NT$11,793 million. The remaining NT$1,171 million came from the Directorate General of Highways under the Ministry of Transportation and Communications. d. Other projects: Refurbishment of another 28 old bridges costs NT$10,340 million. The refurbishment, however, has yet to be approved by the Council for Economic Planning and Development. No approval is given because these bridges do not meet requirements of requirements set forth in the River Management Project and the Regulations Governing the Reviews of River-Crossing Structures. 5. Conclusion Taiwan is mountainous with plenty of precipitation. Typhoons hit the island in summer and autumn. Rivers are short and with a steep gradient. Flash floods triggered by tropical rainstorms do bridges serious damage. Many bridges have collapsed. There are many old bridges that may collapse in floods. Reconstruction of dangerous bridges is an urgent need. To meet that need, the government should see to it that strict quality control is exercised over construction or reconstruction of bridges, which have to be completed on schedule. Designing should be technically improved to make bridges better withstand earthquakes and floods. On the other hand, construction
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CONTENTS Preface Overview ix xi Foc
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Agriculture and Fisheries Impact of
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CHUANG, Yih-chyi( 莊奕琦 ) Pro
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TAN, Ching-yu( 譚瑾瑜 ) Associ
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enth effort on the part of the Foun
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ills pertinent to parliamentary ref
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