Background

This section contains a brief background of the failures that were researched:

Tacoma Narrows Bridge: 

The Tacoma Narrows Bridge was completed in 1940 in Tacoma, Washington. It was a suspension bridge purposing as a road way that spanned 7,392 feet, designed by Leon Moisseiff.  The bridge collapsed in the violent 42 mile-per-hour winds on November 7^th, 1940, in the body of water beneath, the Puget Sound. Fortunately there were no human casualties but a dog stuck inside a car on the bridge did not make it. The failure of this bridge unearthed several problems in the engineering community and forever changed the way bridges would be constructed. 

Figure 1: The Tacoma Narrows Bridge falling into the Puget Sound

Most of the bridge was destroyed when it fell in 1940, and its parts could only be salvaged as scrap metal. The main and suspender cables, two towers, the deck-floor system, side spans, and the piers and anchorages were destroyed beyond repair. Over 350 cables were ripped from their posts.

Figure 2: An example the cables that were ripped from their posts.

The engineers of the time had ignored the fact that aerodynamics played a very large role in bridge design. They focused on making the sides of the suspension bridges as stiff as possible in order to avoid any sideways movement. They also focused on making sure the bridge could with stand a heavy load of moving vehicles. The fact that vertical movement could be a product of high wind speeds was not a factor they took into place when designing their bridges. When the 42 mile-per hour winds hit the bridge in 1940 the bridge could not withstand the pressure and began to move vertically. The winds twisted and bent the bridge, which led to the previously mentioned parts to become unattached and fall into the sound. 

Figure 3: The bending and twisting of the bridge, due to the winds, from a head on view 

Chernobyl Nuclear Disaster:
This was a accident that occurred in 1986 in the city of Pripyat, Ukraine. The reason for the accident stems from a flaw in the reactor in addition to improper knowledge of the employees. At the time of the incident, the fourth reactor's safety mechanisms were turned off as a apart of a test to see if it could function on their backup power sources. The flaw in the reactor's design came into play when the safety tests were underway, specifically the use of control rods became a problem. The rods were removed, which caused the reactor to begin to overheat, then they were reinserted. Upon their reinsertion, they became deformed and jammed the airways of the reactor, which resulted in the reactor exploding. The explosion destroyed the building that the reactor was housed in (Figure 1), but the radiation that was emitted from it was far more dangerous. The radiation emission resulted in a dramatic increases in cases of thyroid cancer, and this was just one of the many problems that stemmed from the radiation. These problems forced the government to create benefit programs to help victims of the radiation. Also, there were laws put into place regarding the safety amongst nuclear plants, in general.

Figure 1: The building that housed Reactor 4, which exploded causing the accident.

Fukushima Daiichi Nuclear Disaster: 
This was a nuclear accident that occurred in Japan. The cause of the accident stemmed from an earthquake and tsunami striking the plant. The accident could be blamed on the engineers who constructed by not accounting for disasters in a disaster-prone region.

Diagram of Primary drywell containment, pressure vessel, and the wetwell

(5/7/15):On Friday, March 11th, 2011, earthquake of magnitude 9.0 hit East Japan which did much damage to the region. When the earthquake hit the Fukushima Daichii and Daini reactors were shut down showing no significant damage. Following the earthquake a tsunami hit shore which inundated 560 sq kilometers, which flooded the Fukushima Daichii reactor at a height of 15 meters. This led to meltdown of the reactor and a compromise of the containment walls, releasing radioactive products into the environment. The disaster was rated a 7 on the international nuclear event scale, but because people were evacuated immediately no one was affected by nuclear radiation. However, the groundwater of the area mixed with highly contaminated water of the basements of the reactors, leading to radioactive waste running off into the sea.

Boston Molasses Disaster: This accident occurred in Boston when there was fluctuations in temperature in the area. The temperature shifts caused the tank that held the molasses to topple over, which caused it flood the town due to the engineering plight.

BP Oil Spill: The Deep Water horizon oil spill, also known as the BP oil spill, was a modern environmental tragedy that occurred when a BP owned oil rig situated in the Gulf of Mexico caught fire and sank, spilling millions of gallons of oil into the Gulf. It is considered the largest accidental marine oil spill in the history of deep water drilling. After the explosion and sinking of the Deepwater Horizon oil rig, the well spilled out oil for 87 days before it was finally capped. The consequences of the spill include environmental turmoil, health consequences for the food sources affected by the spill, sanctions by the US government on deep water drilling, and an outcry of negative publicity for BP.

Figure 1. A model of the drill that was used in Deepwater Horizon rig

Bibliography:

http://www.wsdot.wa.gov/tnbhistory/connections/connections3.htm
http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Chernobyl-Accident/
http://www.world-nuclear.org/info/safety-and-security/safety-of-plants/fukushima-accident/
http://www.historytoday.com/chuck-lyons/sticky-tragedy-boston-molasses-disaster
http://content.time.com/time/interactive/0,31813,2006455,00.html