By Kim Smiley
Brooklyn Bridge marks its 125th birthday on May 24, 2008. When performing a root cause analysis it is easy to spend a large amount of time focused on failures, but today engineers should take a moment to appreciate the accomplishment of this truly amazing feat. The bridge has been refurbished many times, but the towers, main cables, and main beams are original and are now 125 years old.
At the time the Brooklyn Bridge was constructed the 6,000 ft long bridge was roughly six times as long as the longest bridge of the type that had previously been built. The Brooklyn Bridge is one of the nation’s oldest and most treasured suspension bridges. It has shaped the development of New York City. At the time it was constructed Brooklyn was largely rural and the bridge helped sparked a growth spurt that dramatically changed the face of Brooklyn. Brooklyn’s population grew by 42 percent between 1880 and 1890. At last count in 2006, the bridge carried 126,000 cars per day.
Recent inspections have revealed some deterioration of the bridge, primarily with the newer approach ramps. In a recent survey, state inspections ranked its condition as “poor”. New York City plans to spend $250 million to 300 million to fix and repaint the bridge. Hopefully these updates will return the bridge to good condition and it will continue to safely serve the citizen of New York City for many decades to come.
by Kim Smiley
About 1:40 am on May 17, six rail cars derailed and overturned near Lafayette, Louisiana. One of the cars was damaged and leaked about 11,000 gallons of hydrochloric acid. Five people, including two rail workers, were sent to a hospital and treated for eye and skin irritation.
Authorities evacuated people with 1 mile of the accident. Approximately 3,000 people were affected, including a few small businesses and a nursing home. All affected people are being reimbursed for food and hotel costs by the railway company that operated the train.
There was potential for further release of chemicals because one of the rail cars involved in the accident carried ethylene oxide, a flammable and dangerous chemical, and two of the remaining cars also carried hydrochloric acid.
The Louisiana State Police’s hazardous materials unit is overseeing clean-up of the accident site. The spill is being neutralized with lime and the contaminated material will be removed and disposed of. The rail car containing ethylene oxide was removed from the site quickly to reduce the potential for additional problems.
The cause of the derailment is not known at this time. The Federal Railroad Administration will conduct an investigation of the accident.
The attached PDF file contains an intermediate level root cause analysis of the train derailment built using Cause Mapping, a visual form of root cause analysis. It was built using the facts that were available in media reports on the accident. As more details are known, the Cause Map can be expanded.
By Kim Smiley
Early in March 2008, NASA announced that the shuttle mission to the Hubble telescope would take place in the fall rather than in August as originally scheduled. A trip to Hubble is necessary to replace gyroscopes and batteries that failing. Additionally, the mission will also be sued to install instruments that will increase the range of the telescope. The changing schedule itself is not a cause for alarm, but the reasons between the slip are interesting. The changing schedule shows that NASA is still struggling to recover from the tragic loss of the Columbia in many ways.
The shuttle mission is delayed because new design fuel tanks will not be manufactured in time to support the original schedule. In 2003, Columbia and her crew were lost when external foam fell off the fuel tank during ascent and struck the wing of the orbiter creating a plate size hole. Initially, NASA managed the foam issue by modifying existing fuel tanks. The last of these pre-existing fuel tanks will fly with Discovery when the shuttle launches for a space station assembly mission May 31. The fuel tanks for future launches are being built with design modification to prevent foam loss. This manufacturing process is taking four to five weeks longer than originally planned. No information is available in media reports explaining why the manufacturing schedule is longer than expected.
The mission to the Hubble telescope is also the only shuttle mission planned that will not go to the international space station. This fact is relevant because it means that two shuttles have to be prepared for launch, not just one. Two shuttles means double the work needed to get the new fuel tanks ready for launch. A second shuttle will be prepared in the event a rescue mission is needed. Trips to the space station are less risky because the astronauts could seek shelter in the space station if the orbiter was damaged, providing a much longer window for potential rescue.
The attached PDF file contains an intermediate level root cause analysis of the delay of the Hubble shuttle mission. It was built using the facts that were available in media reports. As more details are known, the Cause Map can be expanded.
By Kim Smiley
An Associated Press article, published on April 25, highlighted a common, often ignored problem of customers getting a different amount of gas then what they paid for. Gas pumps contain a check valve that allows gas to start flowing at the same time the price meter starts. As the check valves age, they can begin to hesitate and wait a period of time before gas flow begins. This results in the consumer being overcharged because the price meter is turning before gas is flowing. Worn check valves usually only cost consumers pennies per fill-up, but there have been instances of overcharges of 30 to 40 cents a gallon. This issue doesn’t cost the consumer large amounts of money, but it adds frustration to a public already aggravated by record high gas prices.
To be fair, it should be mentioned that worn check valves sometimes help the consumer as well. When a check valve hesitates at the end of a fill up, the price meter is stopped and a small amount of gas will continue to flow. Also, to clarify, this isn’t a case of gas stations purposely gorging consumers. It’s a situation where a common piece of machinery is wearing out and not functionally properly.
To help prevent these types of errors, gas pumps are regularly inspected to ensure that consumers are charged for the correct amount of gas. Regulations allow gas pumps to pass inspection if they overcharge by no more than 6 cents for every five gallons delivered. Most states require gas pumps to be inspected every year to ensure accurate measurement of gas delivered. Many counties try to inspect more frequently, but have difficultly because of staffing shortages and financial pressure.
The attached PDF file contains an intermediate level root cause analysis of the worn check valves in gas pumps. It was built using the facts that were available in media reports. As more details are known, the Cause Map can be expanded.