1 Shoddy construction killed 600
Unsafe foundation In 1924-26, the famous engineer William Mulholland was responsible for the construction of the St. Francis Dam in California. Mulholland ignored several warnings of cracks, and during the night of 13 March 1928, things went wrong: The dam broke, and 46 million cubic metres of water surged into the Santa Clara Valley, killing approximately 600 people. William Mulholland had built the dam in a canyon with loose rock and increased its height without making the foundation proportionally thicker. Moreover, he had not made sure that water could not pass under the wall. The result was inevitable, and terrible
2 Miscalculation changed ecosystem
Underground cavity On 21 November 1980, 12 Texaco employees were drilling for oil in the three metre deep Lake Peigneur in Louisiana Approximately 400 m into the ground, the drill became stuck, and the rig began to falter. The men managed to get themselves ashore, before the rig disappeared in a huge sinkhole. The workers had struck the Diamond Crystal salt mine, which was located beneath the lake. Texaco knew about the mine, but had miscalculated the drilling coordinates. The fresh water from the lake dissolved the salt, and the mine collapsed. Air was forced towards the surface in a series of 120-m-high
geysers. Apart from the rig, the whirlpool swallowed trees, trucks, and 11 barges. The miscalculation caused a backflow from the ocean, converting a shallow fresh water lake into a deep salt lake with a new flora and fauna.
3 Fighters "shot down" by date line
Date confusion
Suddenly, all the electronics of 12 American F-22 Raptor fighters died in mid-air. The planes were on their first international flight from Hawaii to Okinawa, Japan, on the 24th of February 2007. When they passed the international date line in the Pacific, the unexpected change of date made all systems shut down, as programmers had forgotten to allow for the date line. The pilots could neither navigate nor check the fuel of the planes, and the systems for communicating with the outside world also partly failed. The pilots followed big tanker planes back to Hawaii, where visibility was good, allowing them to land the fighters manually. Had the weather been bad things could have become critical.
4
Cancer patients killed by computer
Code glitch In 1985-1987, the
Therac-25 radiation therapy machine
killed at least six cancer patients in
Canada and the US. The radiation
machine normally produced electron
beams, but it also featured a 125 times
more powerful X-ray beam. A computer
error meant that if the operator chose the
wrong type of beam, but corrected the
mistake before therapy, the Therac-25
became confused, reversing the
operator’s decision without any indication
in the control panel. So, on several
occasions, patients were subjected to
X-rays even though the machine was
supposed to carry out electron therapy.
5
Measuring units killed off Mars probe
Conversion error On 23 September
1999, NASA lost all contact with its Mars
Climate Orbiter. The probe had completed
the 10 month journey to Mars without
problems, but shortly after entering its
orbit around Mars, something went wrong.
The probe had probably come too close to
the planet, and it crashed or burned in the
atmosphere. The accident was due to a
communication error concerning
measuring units, and so, the probe was fed
incorrect numbers. Lockheed Martin used
pound-seconds to calculate output. NASA
sent the data to the probe, believing it was
being read in newton-seconds.
6
History’s most expensive hyphen
Forgetfulness On 22 July 1962, NASA’s
new 80 million dollar Mariner 1 probe unexpectedly
changed direction after launch.
The change of course was due to an error in
the probe’s computer instructions involving a
missing hyphen over an R in a maths formula.
7
Platform caused earthquake
Design flaw The Sleipner A offshore
platform sank in 1991. Engineers had underestimated
the load-bearing strength of the
concrete by 47 %, and the huge structure
crashed into the fjord floor at a depth of 220 m,
creating magnitude three earthquake.
8
Square windows caused plane crash
Stress impact In 1954, two De Havilland
Comets crashed due to their square windows.
Up to 70 % of the pressure that the plane was
subjected to in the air accumulated at the
corners of the windows, making the metal
crack. All subsequent airliners have been
designed with rounded windows.
9
Bridge swayed and collapsed
Resonance In 1940, gusting winds of
68 km/h made the Tacoma Narrows bridge
collapse. The wind hit the resonant frequency
of the bridge and stepped up the effect,
so the bridge self-oscillated and
collapsed, killing a dog.
10
Glue caused collapse
Glue failure A car
passenger was killed when a
tunnel collapsed in Boston on
10 July 2006. The disaster took
place in the Big Dig underground road
system, where 23 tonnes of concrete and other
material fell from the ceiling. Tunnel designers
had chosen the wrong epoxy glue for the spikes
that held the ceiling in position. The glue dried
fast, but lost its strength after a few weeks.
Unsafe foundation In 1924-26, the famous engineer William Mulholland was responsible for the construction of the St. Francis Dam in California. Mulholland ignored several warnings of cracks, and during the night of 13 March 1928, things went wrong: The dam broke, and 46 million cubic metres of water surged into the Santa Clara Valley, killing approximately 600 people. William Mulholland had built the dam in a canyon with loose rock and increased its height without making the foundation proportionally thicker. Moreover, he had not made sure that water could not pass under the wall. The result was inevitable, and terrible
2 Miscalculation changed ecosystem
Underground cavity On 21 November 1980, 12 Texaco employees were drilling for oil in the three metre deep Lake Peigneur in Louisiana Approximately 400 m into the ground, the drill became stuck, and the rig began to falter. The men managed to get themselves ashore, before the rig disappeared in a huge sinkhole. The workers had struck the Diamond Crystal salt mine, which was located beneath the lake. Texaco knew about the mine, but had miscalculated the drilling coordinates. The fresh water from the lake dissolved the salt, and the mine collapsed. Air was forced towards the surface in a series of 120-m-high
geysers. Apart from the rig, the whirlpool swallowed trees, trucks, and 11 barges. The miscalculation caused a backflow from the ocean, converting a shallow fresh water lake into a deep salt lake with a new flora and fauna.
3 Fighters "shot down" by date line
Date confusion
Suddenly, all the electronics of 12 American F-22 Raptor fighters died in mid-air. The planes were on their first international flight from Hawaii to Okinawa, Japan, on the 24th of February 2007. When they passed the international date line in the Pacific, the unexpected change of date made all systems shut down, as programmers had forgotten to allow for the date line. The pilots could neither navigate nor check the fuel of the planes, and the systems for communicating with the outside world also partly failed. The pilots followed big tanker planes back to Hawaii, where visibility was good, allowing them to land the fighters manually. Had the weather been bad things could have become critical.
4
Cancer patients killed by computer
Code glitch In 1985-1987, the
Therac-25 radiation therapy machine
killed at least six cancer patients in
Canada and the US. The radiation
machine normally produced electron
beams, but it also featured a 125 times
more powerful X-ray beam. A computer
error meant that if the operator chose the
wrong type of beam, but corrected the
mistake before therapy, the Therac-25
became confused, reversing the
operator’s decision without any indication
in the control panel. So, on several
occasions, patients were subjected to
X-rays even though the machine was
supposed to carry out electron therapy.
5
Measuring units killed off Mars probe
Conversion error On 23 September
1999, NASA lost all contact with its Mars
Climate Orbiter. The probe had completed
the 10 month journey to Mars without
problems, but shortly after entering its
orbit around Mars, something went wrong.
The probe had probably come too close to
the planet, and it crashed or burned in the
atmosphere. The accident was due to a
communication error concerning
measuring units, and so, the probe was fed
incorrect numbers. Lockheed Martin used
pound-seconds to calculate output. NASA
sent the data to the probe, believing it was
being read in newton-seconds.
6
History’s most expensive hyphen
Forgetfulness On 22 July 1962, NASA’s
new 80 million dollar Mariner 1 probe unexpectedly
changed direction after launch.
The change of course was due to an error in
the probe’s computer instructions involving a
missing hyphen over an R in a maths formula.
7
Platform caused earthquake
Design flaw The Sleipner A offshore
platform sank in 1991. Engineers had underestimated
the load-bearing strength of the
concrete by 47 %, and the huge structure
crashed into the fjord floor at a depth of 220 m,
creating magnitude three earthquake.
8
Square windows caused plane crash
Stress impact In 1954, two De Havilland
Comets crashed due to their square windows.
Up to 70 % of the pressure that the plane was
subjected to in the air accumulated at the
corners of the windows, making the metal
crack. All subsequent airliners have been
designed with rounded windows.
9
Bridge swayed and collapsed
Resonance In 1940, gusting winds of
68 km/h made the Tacoma Narrows bridge
collapse. The wind hit the resonant frequency
of the bridge and stepped up the effect,
so the bridge self-oscillated and
collapsed, killing a dog.
10
Glue caused collapse
Glue failure A car
passenger was killed when a
tunnel collapsed in Boston on
10 July 2006. The disaster took
place in the Big Dig underground road
system, where 23 tonnes of concrete and other
material fell from the ceiling. Tunnel designers
had chosen the wrong epoxy glue for the spikes
that held the ceiling in position. The glue dried
fast, but lost its strength after a few weeks.
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