Design errors, poor management and inadequate maintenance are among the probable causes of the collapse of a steel arch bridge in northeastern Taiwan that killed six people last year, according to an investigation report issued Wednesday.
The Taiwan Transportation Safety Board said in the report that the collapse of the Nanfangao Bridge at a fishing township in Yilan County was mainly caused by corrosion of the steel cables coupled with inadequate maintenance and improper management.
Board member Yeh Ming-shan told a press conference that each main cable of the bridge, completed in 1998, consisted of parallel steel wires arranged in strands to form a cylinder protected by a layer of zinc from salt corrosion. While main cables near the anchorages were protected by high-density polyethylene, there were no drain holes, making it easy to accumulate water therefore causing erosion, Yeh said.
The report also pointed out that while the bridge was reinforced in 2017 and again in 2018, the last inspection was three years and seven months before the accident and only done visually, Yeh said.
The bridge collapsed around 9:30 a.m. on Oct. 1 last year, killing six foreign crewmen -- three Filipinos and three Indonesians -- who were working on two Taiwanese fishing vessels that were crushed.
Thirteen others were injured, including nine foreign crewmen and the driver of an oil tanker truck that had driven across the bridge and almost reached the other side when it suddenly gave way. The truck fell into the waterway and caught fire.
After the deadly accident, a number of remedial actions have been taken, including Ministry of Transportation and Communications ordering the inspection of the 101 bridges under its supervision.
The rebuilding of the Nanfangao Bridge began last month and is scheduled for completion in August 2022.
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