The Vasa

Source: Vasa Museet


This Swedish ship was constructed between 1626 and 1628 and intended to be part of the Royal Swedish Navy. However, it only got 1300 metres into its maiden voyage before it capsized and sank. King Gustavus Adolphus oversaw the project and put tight time constraints on the engineers to get the ship finished. He also requested design changes mid-project, despite the constructers advising against them. Once the construction was finished, engineers conducted stability tests on the ship and concluded it was not sea worthy. The King ignored this and ordered it to be launched anyway. Light breeze caused the ship to capsize as soon as it left the harbour, and the ship sank as water flooded into the gun portals. 53 sailors lost their lives.

St Francis Dam


The St Francis Dam in California had been operational for two years, when in 1928 it exploded and killed over 450 people. Constructed out of concrete, it started showing signs of cracking shortly after being filled. This is because the dam was built from plans that were originally meant for another site, with no location-specific modifications. During construction, the height of the dam was increased twice, but the base remained the same – this reduced the safety margin for structural stability significantly. For a considerable amount of time leading up to the explosion, muddy water was observed entering the dam from within the foundation. The dam failed less than 12 hours after the last inspection by its engineer.

Purity Distilling Company Tank

Source: Boston Public Library


On 5 January 1919, a giant molasses tank blew up and coated a Boston neighbourhood in sticky syrup, killing 21 people and injuring 150. Molasses wasn’t only used to make rum; during World War 1 it was used to make munitions. This tank was built hastily because of the war and as a result, it was never filled to capacity to test for leaks. As soon as it was filled with molasses it began leaking, so the owners painted it brown to camouflage the stains. Investigations into why the tank exploded were inconclusive; however some possible causes were a too-brittle tank or a reaction caused by a mix of hot and cold molasses brought on by extreme changes in temperature. When the tank exploded, 8.7 million litres of the syrup peaked at 27 metres and rushed into the streets at 56 kilometres per hour.

R101 Airship

Source: Daily Mail


In 1930, British Airship R101 crashed killing 48 people. Originally this airship was conceived by the British Government as an experimental platform. However, after completion, the government decided they’d like the airship to fly commercially in order to compete with a German plane which had just successfully flown around the world. Engineers weren’t given time to fix any of the structural and mechanical issues in the design, nor were they able to run flight trials. As a result, the plane was heavier than intended and the engines were half as powerful, yet twice as heavy as planned. The plane was dispatched on a flight to India, despite being unfit to make the journey and with no regard to the bad weather. The load of fuel and unnecessary cargo exceeded the ship’s abilities and compounded the other design flaws.

Tacoma Narrows Bridge Collapse

Source: Failure Mag


In November 1940, the third longest suspension bridge in the world collapsed, killing one dog. The Tacoma Narrows Bridge was designed to be the most flexible bridge ever constructed and despite exceeding standard ratios for length, width and depth, it was considered completely safe. It was later found that the engineers responsible for the project hadn’t taken into account all the aerodynamic forces brought about by strong winds. The sustained wind that passed over the structure that day caused vortices to occur, which started rocking the extremities of the bridge out-of-time with its middle. This caused one of the suspension cables to snap and the motion intensified, causing the entire structure to collapse.

Cleveland Gas Explosion


In 1944, two liquid gas tanks exploded in Cleveland, Ohio, killing 130 people. There were four above-ground tanks used as storage for the gas and one began leaking, sending white vapours into the air. The wind pushed the vapours towards the sewage system, which created the explosion. This storage tank caught fire and began destroying houses and factories in the area. As firefighters worked on it, a second tank also caught fire. 600 people were left homeless as a result of the damage. It took the all the firefighters in that town to put the fires out.

The de Havilland Comet

Source: Pilot's Post


The world’s first commercial aeroplane featured turbojet engines rather than propellers, a bullet-shaped body, a pressurised cabin and square windows. These engines allowed it to fly higher than its competitors, avoid bad weather and increase its speed by up to 50 per cent. Built in 1949, it was commissioned by airlines such as Pan Am, South African Airways, Japan Airlines and Air India. In its first year it flew 30,000 passengers including Queen Elizabeth, taking customers from London to places such as Tokyo, Colombo and Johannesburg. By 1953 Comets were leaving London each week. However, there was a major structural design flaw which became evident after two crashes occurred in 1954.
On flight 781 from Rome, the plane exploded 20 minutes after take-off killing everyone on board. Crash investigators found the recovered bodies all had fractured skulls and ruptured lungs. When a South African airways plane crashed a few months later, the recovered bodies had all suffered similar injuries. Investigators found both accidents were caused by inflight metal fatigue failure, which led to explosive mid-air compression. The square windows were to blame for this – the sharp corners of the windows put the surrounding metal under stress at high altitude. Since the stress was localised to just the corners of each window, it resulted in metal fatigue. This is why round windows are always used in aeroplanes now; the stress is able to flow evenly around the window.

Firestone 500 Tires

Source: Corvette Forum


There were over 60 deaths and a hundred serious injuries caused by Firestone 500s across the US, culminating in a recall of millions of tires in 1978. Firestone was a popular tire brand in US prior to the 1970s, however, when radials became available in the American market their sales began to fall behind. In response, they engineered a radial tire but cut corners in order to release it in the shortest amount of time possible. One of the biggest issues in the manufacturing process was the use of incorrect machinery, as the radial-specific equipment was yet to be installed. Over a period of four months the tires passed high speed tests, high mileage tests and overload tests at maximum weight. A couple of years after the tires had been put on the roads, major accidents occurred, caused by tread rubber separating from the brass-plated steel belt at high speeds. While the cause of this separation was never proven, it’s believed the tread wasn’t adhered to the steel belt correctly and water got in, causing the belt to corrode.

Kansas City Hyatt Regency Walkway Collapse


In July 1981, two walkways collapsed at the Hyatt Regency Kansas City hotel killing 114 people and leaving over 200 injured. During its construction the 40-storey building experienced some setbacks, including the collapse of the atrium roof. The lobby was one of the hotel’s defining features, with steel, glass and concrete walkways connecting the second, third and fourth floors from north to south. The walkways had been designed with support beams and tie rods to carry the weight of the people standing on them. However, the design of the fourth-storey walkway had been modified slightly, and the change critically undermined the safety of the structure. On the night of the tragedy, 1600 people were in the lobby for a Tea Dance event. There were approximately 40 people on the second-storey walkway and 16 on the fourth-storey walkway. The connections supporting the ceiling rods holding up the second and fourth-storey walkways failed, causing them to collapse onto the crowded first floor.

Therac-25 Medical Accelerator

Source: Hackaday


Between 1985 and 1987 six cancer patients were exposed to overdoses of radiation, killing four of them and permanently injuring two. This was caused by a “cancer zapping” machine, which used X-rays to kill cancerous tissues in patients. One of the issues with this machine was that healthy tissue around the tumour was always damaged too, however, it was always hoped the patient would be healed more than they would be harmed. It turned out the machine was only controlled by a computer and there were no hardware interlocks or supervisory circuits to ensure safety. Engineers had also failed to conduct time-analysis and unit testing of the machine. The software developed a bug, which lead to catastrophic events as the wrong dosage was delivered to patients.
Originally the manufacturers denied that such an error was possible, however a technician familiar with the machine ran experiments in his own time to find out what was causing it to malfunction. It was found the same error could happen in the previous model; however the hardware interlocking system would act as an emergency stop. Since this system had been removed in the current model, there was nothing to stop the machine from administering an overdose. The computer had been programmed to have real-time control over the machine. However when the software was placed under scrutiny, it was revealed the source code had been written by only one person who had little experience with coding for real-time systems. The Therac-25’s code had just been based off the code for the two previous models. Both the software engineers and system engineers were at fault for not properly testing the machine and ensuring tight safety measures were in place.

Chernobyl Disaster

Source: Wikipedia


In 1986, workers at the Nuclear Plant were preparing for a one-time shutdown, when they violated safety regulations by disabling the automatic shutdown system and removing most of the control rods, while allowing the reactor to continue running at seven per cent. This caused two large reactions to occur , sending radioactive material into the air. In the four months that followed 28 workers died – some knowingly exposed themselves to the deadly levels of radiation in order to prevent the plant from leaking further. Since the radioactive material affected such a large geographical area, many people were displaced from their homes. Thousands of people died prematurely from cancer because they were exposed to such high levels of the poison.

McDonnell Douglas DC-10


These commercial planes were manufactured from 1970-1989 and designed to compete with the Boeing 747 by operating medium to long haul flights. Over 1000 people were killed in a series of incidents brought about by various engineering errors. Two of these incidents involved faulty locking mechanisms on the cargo door, causing it to be ripped off mid-flight and depressurise the cabin. In another incident, the left pylon and engine separated from the wing just after take-off, which cut several hydraulic lines at the same time. 275 people died in the resulting crash.

Mars Climate Orbiter

Source: Wikipedia


This US $125 million satellite was designed to be the first weather observer on another planet. However, in September 1999, it vanished as it approached Mars, burning up in the atmosphere. NASA reviewed their calculations and realised a conversion error caused the spacecraft to go too close into the Martian atmosphere. The software controlling the satellite’s thrusters calculated the necessary force it needed to exert in pounds. Another piece of software took this calculation and assumed it was in newtons. Unfortunately, the engineers didn’t pick this error up despite the spacecraft making 10 times the amount of adjustments than they expected. It got within 60 kilometres of the Martian surface despite simulations showing anything closer than 85 kilometres would exert enough atmospheric friction to destroy the satellite.

The Millennium Footbridge

Source: Walk London


This footbridge was opened in June 2000 to celebrate the new millennium and connected St Paul’s Cathedral with the Tate Modern Gallery. Two days later, it was closed indefinitely as engineers re-worked the structure’s design. The US $26 million bridge showcased a futuristic design with an aluminium deck supported by two Y-shaped frames, rather than overhanging arches. Unfortunately, the bridge was wobbly and even a light breeze made it swing. As pedestrians crossed the bridge, they attempted to keep their balance by walking in time with the swaying to counter the motion. This increased the force of the lateral swinging and the rocking increased. New York engineers stepped in and installed 87 dampers underneath the bridge to act as shock absorbers and decrease the motion, costing a further US $7 million. The bridge was reopened 18 months later.

Tokyo Disneyland Big Thunder Mountain Derailment


One person was killed and 10 injured when the rollercoaster derailed in 2003. The gap between the axel and the bearing on the back wheel exceeded design specifications, causing more vibration than it should have and placed extra pressure on the screw holding the axel in place. As a result, the axel broke and the carriage crashed. The reason for the large gap was a miscalculation in measurements when converting them from imperial to metric – the axel should have been 44.14 millimetres rather than 45 millimetres.

French Trains Too Wide For Platforms

Source: Alamay


In 2014, French train operator SNCF discovered the brand new trains they had ordered at a cost of €15 billion were too wide for many of their regional platform. The trains had been purchased to fit the measurements of platforms built approximately 30 years ago, without taking into consideration the skinnier platforms built 50 years ago. To solve this problem, the rail operator had to spend upwards of €50 million to reconfigure over 1000 platforms across the country.

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