Five Biggest Engineering Disasters

As engineers continue to push the boundaries of scientific invention and exploration, along with great achievements unfortunately come terrible failures too. Fortunately, from mistakes lessons are learned but sometimes only once a high price has been paid.

Among the greatest tales of engineering disasters are nuclear reaction explosions, the sinking of great vessels and explosions of space searching rockets. Five of the biggest are the subject of this article and it has been debatable which to include. There were numerous to choose from such as the the World Trade Center; the Deepwater Horizon Oil Spill; Hyatt Regency Hotel Walkway Collapse; the 1970s DC-10 Disasters; Apollo 1, and the failure of the New Orleans Levee System during Hurricane Katrina.

While all these disasters remind us of the scale of human endeavour, there is massive potential for failure in the more ordinary. Even bearings, that every day yet essential engineering component of moving systems cannot be overlooked – an overheated one caused an engine failure which caused an engine fire, which led to cabin decompression and finally to the crash of an aircraft in Poland in 1987 – resulting in 193 fatalities.

Engineering is a precise science. Attention to detail and the highest safety standards must be adhered to at all times. Perhaps the most important lesson for us all is not to consign these events to history but to make sure they continue to be recognised by tightened regulations. These lessons also serve as a reminder for people to speak up when necessary to avoid these mistakes being made again.

1. Chernobyl

In the early hours of 26 April 1986, a structurally unsound reactor at Chernobyl Nuclear Power Plant near Pripyat in Ukraine in the Soviet Union exploded. It caused the release of massive quantities of radioactive particles into the atmosphere which spread over much of Western USSR and Europe. 350,400 people were evacuated and resettled from the most severely contaminated areas of Belarus, Russia, and Ukraine.

The disaster began during a systems test when there was a power surge followed by an emergency shutdown and an exponentially larger spike in power output. The reactor vessel ruptured, there was a series of steam explosions, and the reactor’s graphite moderator was exposed to the air, causing it to ignite. The resulting fire sent a plume of highly radioactive fallout into the atmosphere over an extensive geographical area.

In terms of human deaths, the Chernobyl nuclear accident was one of the worst energy accidents in human history. Figures vary widely but between 31 and 64 deaths have been directly attributed to the incident, with estimates of up to 4,000 deaths among those exposed to the highest levels of radiation. Among those living in the broader geographical areas, the numbers of those affected range from 30,000 to nearly a million premature cancer deaths.

2. The Bhopal Disaster 

In 1984, a toxic gas release at a Union Carbide pesticide plant in Bhopal, India resulted in 2,259 immediate deaths and some 11,000 deaths following the disaster.

Over 42 tons of Methyl isocyanate - a highly toxic and irritating material used in the making of pesticides – became contaminated with water, causing an exothermic reaction, which increased the temperature inside the tank to over 200°C , far beyond its capacity. Automated emergency release systems kicked in, venting the extra pressure and a large volume of gasses, which escaped and began to spread. Had that gas been lighter than air, it might have dispersed with minimal harm. Unfortunately, being heavier than air, it crawled for miles, seeping into the nearby city of Bhopal. A government affidavit in 2006 stated the leak caused 558,125 injuries including 38,478 "temporary partial" and approximately 3,900 "severely and permanently disabling" injuries.

It has now been 25 years since the horrific disaster, yet still the land around Bhopal remains blighted and toxic to humans and animals alike. Today, the 390 tons of toxic chemicals continuing to pollute the groundwater in the region. The disaster serves as a reminder for the way the industry approaches process safety management (PSM). The right decisions need to be made daily to ensure the safety of your process – and this in turn helps ensure the meaning of the phrase “recognised and generally accepted good engineering practices.”

3. Titanic 

The sinking of the Titanic is history's most epic sea disaster and the topic of endless books, feature films and documentaries.

In 1912, the world’s largest ship, on its maiden voyage carrying some of the world’s richest people had a freak accident with a catastrophic loss of life. Four days into her journey, on the night of 14th April the Titanic struck an iceberg in the North Atlantic and was so badly damaged that she survived for less than three hours before she sank. Two thirds of Titanic’s passengers and crew were lost because there were not enough lifeboats to rescue everyone on board. Over 1500 people drowned.

It is believed that safety took second place to aesthetics in the ship’s design. The original design included two rows of lifeboats on the deck, but one row was removed allowing more space and a better view for passengers with first-class berths. This was not against the Board of Trade regulations which covered only ships up to 13,000t and not the 46,000t Titanic.

Research has found it likely that the iceberg buckled the plates and popped out substandard rivets along a length of the hull, allowing water into at least five of the watertight compartments. As the boat went down by the head, water flowed over the transverse bulkheads, which were barely above the waterline, into other compartments. It has been said that the height of the bulkheads was reduced to avoid spoiling the first-class public rooms.

In the aftermath of the disaster, the height of transverse bulkheads was increased and double hulls reaching further up the sides of ships became common. There were new regulations regarding safety, increasing the number of lifeboats and allowing easy access to them for all passengers. There were also changes regarding the use of radio at sea.

4. The Space Shuttle Challenger

Just 73 seconds after its launch, on 28 January 1986, space shuttle Challenger broke apart, killing its seven crew members. The subsequent Rogers Commission found the cause of the accident was the failure of both primary and secondary O-rings on the right solid rocket booster, allowing hot gas and flame to escape, which then came into contact with the booster attachment and external tank, resulting in structural failure. The problems with the O-rings had been known about for nine years but had been ignored, partly because safety was deemed ensured with the presence of the second ring. However, as was later made clear, the second ring was there for unforeseen failure, not a failure that had been considered. Engineers' warnings that low temperatures would exacerbate the problem were also ignored by NASA managers because of pressure to keep to the launch timetable.

Now widely used as a case study for trainee engineers, this disaster has been used to teach many lessons: primarily that that the advice of engineers should be considered carefully by management; and that the ethics of whistle-blowing and group decision-making should be introduced. Afterwards, there was a total redesign of the solid rocket boosters, in which three O-rings were incorporated, watched over by an independent oversight group as stipulated by the commission.

In summing up the disaster, Richard Feynman, a member of the Rogers Commission, made a telling point to the effect that "for a successful technology, reality must take precedence over public relations, for nature cannot be fooled".

5. Apollo 13

The disaster about the crippled flight to the moon in 1970 that gave the film industry two of the most iconic film lines: “Houston, we have a problem” and “failure is not an option”.

Apollo 13 was the seventh manned mission in the American Apollo space program and the third intended to land on the Moon. The craft was launched on April 11, 1970, at 13:13 CST from the Kennedy Space Center, Florida, but the lunar landing was aborted after an oxygen tank exploded two days later, crippling the service module upon which the Command Module depended.

Despite great hardship caused by limited power, loss of cabin heat, shortage of potable water, and the critical need to jury-rig the carbon dioxide removal system, the crew returned safely to Earth on April 17.