In Taiwan, a huge 140 meter (459 feet) bridge collapsed in October of 2019, the event is known as the “Taiwan Bridge Collapse”. The oil tanker that was traversing the bridge at the time fell into the water and caused a fire when it struck three fishing boats that were below the bridge. This resulted in the injury of over a dozen people and unfortunately the death of six people on fishing boats.
The famous Nanfang’ao bridge was a long single-arch, relatively young bridge at just 20 years old. Reasons for the collapse were unknown at the time, but corrosion and poor maintenance were established as issues early on.
The bridge was finished in 1998 and created a path over the river in a village known for its fishing in Yilan County. It was built in order to replace a much lower existing bridge which prevented larger fishing boats from sailing underneath. This was the very first single-arch bridge that was hung by cables in Taiwan and the second of its kind (single-arch steel cable bridge) in the world. It was about 18 meters high and was quite a popular tourist attraction.
Possible Causes of Taiwan Bridge Collapse
This was not the first time that the bridge had experienced problems with its structure, rusted cables had been found in previous years and connection points for the cable had been hit by vehicles, damaging them. The expansion joints were also of major concern. They were designed to absorb changes in temperature, and motorists had also reported they could feel a difference in the road level on either side of the joint, a sign of warping.
This was not the first time that Nanfang’ao bridge had experienced problems with its structure, rusted cables had been found in previous years and connection points for the cable had been hit by vehicles, damaging them. The expansion joints were also of major concern. They were designed to absorb changes in temperature, and motorists had also reported they could feel a difference in the road level on either side of the joint, a sign of warping.
The consultants that discovered these issues had reported them multiple times to the harbor administration, but they received no response to their attempts to prevent this disaster. The Taiwan International Ports Corporation was created in 2012 and is included under the more powerful Ministry of Transport and Communications. Their issues were supposed to be taken care of during the regular maintenance and repair of guardrails, steel reinforcements and other maintenance items.
There had also been a typhoon (Typhoon Mitag) affecting the area at the time of the collapse, but reports say that the storm had passed long before the bridge gave way. Specialists declined to confirm if the 85mph winds affected the bridge’s strength or not.
The cause of Taiwan Bridge Collapse: Corrosion
After the debris from the collapse had been taken care of, the official investigation commenced with their initial focus being on corrosion in suspension cables that may have been caused by saltwater ingress. This was deemed to be a viable cause of the disaster as according to the bridge consultants, there are just three main components that make up the bridge, the tension ties in the deck, the tension hangers that support the deck and the compressive arch. The arch was not the issue as it looked intact right up until the point that it hit the water.
It was determined that since the tension hangers had all (or at least most) failed halfway through the collapse, they were the cause of the overall collapse of the bridge. The bridge desk had no option but the bend at the middle when it stopped received the support of the hangers. The overall consensus agreed with this, but there was also some evidence to support (excuse the pun) that the original balance of forces between the reinforced concrete at the base of the bridge and the girders (both made/reinforced with steel) had also been affected.
Modern bridge failures have been accredited to neglecting maintenance and corrosion. The Taiwanese government has committed to replacing the bridge in just three years, using $17 million to fund the new project. Hopefully it is more successful than its predecessor!
Failures have been a big part of engineering history and there have been some truly shocking ones, check out the top 25 worst engineering disasters ever here! Since failures like the Taiwan Bridge Collapse, Tacoma Bridge Collapse, Genoa Bridge collapse, Urdaneta Bridge collapse, and the Millenium Bridge Disaster, there have been numerous laws and code brought into place to ensure that disasters like these become rarer occurrences.
Even though the actual cause has still not officially been announced to this collapse, numerous factors such as improper construction of the bridge, over 60 road work projects being completed on it in just 14 years, and overall neglect of the bridge’s structural integrity undoubtedly were factors to this deadly disaster. We are still waiting for the incident to come out to this day (December 2020.)
What do you think caused the failure of the Nanfang’ao bridge? What is the worst engineering disaster that you know of? Let us know with a comment down below!
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