Adhering to his vision of providing people across Tainan City with “a flood-free home,” Mayor William Lai has made flood control his top priority since taking office, and included water resources management in the “Ten Major Plans for Constructing Tainan.” The Tainan Public Works Bureau, for one, started reworking the flood-prone Pingyang Bridge and Yufeng Bridge in Shanshang District in June and October 2012, respectively, enhancing their drainage efficiency with an increase in the bottom elevation as well as cross-sectional area of flow.
Tainan City accounts for a third of Taiwan’s flood-prone areas, but remains NT$45 billion short of its flood control budget target, Lai said, citing the Water Resources Agency. The financially struggling city government, nevertheless, allotted NT$1.6 billion towards a 2-year emergency project to fight flooding.
At a deck width of a meager 4.5 meters, Pingyang Bridge made driving maneuvers a daunting challenge, although it provides a major link between the two villages of Pingyang and Yufeng. According to Tainan Public Works Bureau, it is a submersible bridge with such a low bottom elevation and small cross-sectional area that the inter-village traffic was cut off every time a downpour occurred, leaving its deck submerged. Similarly, Yufeng Bridge stands in a low-lying area downstream of Cailiao River, an important branch of Zengwen River, and is just 300 meters from the confluence of Cailiao and Zengwen Rivers. Lacking span length, bottom elevation and cross-sectional area, the original Yufeng Bridge was invariably inundated by the swollen Cailiao River due to fierce rainfalls. Its 5-meter-wide deck did not accommodate the traffic volume, either. For safety and accessibility reasons, both bridges were remodeled in line with the Water Resources Agency’s review summary on Cailiao River management; while the Pingyang Bridge project was started on June 18, 2012 and completed exactly one year later, the Yufeng Bridge project was implemented between October 29, 2012 and February 20, 2014.
The NT$38.54 million Pingyang Bridge project covered a 305-meter-long, 7-meter-wide area (from 0K+000m to 0K+305m) in total, and involved a 2-span, 90-meter-long, prestressed I-girder bridge, ramps measuring 215 meters combined, and roadway lighting. The approximately NT$56.28 million Yufeng Bridge project addressed a 435-meter section of City Road No. 184 (from 0K+580m to 1K+015m), including a 135-meter stretch of Cailiao River-spanning Yufeng Bridge and ramps on either side, as well as an expanded, 9-meter-wide deck. Both bridges were engineered with augmented bottom elevation, span length and cross-sectional area to avoid not only troubles in driving maneuvers, but also rainfall-induced flash floods that often resulted in levee breaches and submerged riverside lands.
Fortifying flood-prone areas against deluges always lies at the core of Greater Tainan’s public works programs. With a higher bottom elevation and a more efficient drainage system, the beefed-up Pingyang and Yufeng Bridges further ensure the safety and comfort of bridges and passageways city-wide.