[University]
Sunshine Skyway Bridge Disaster of 1980 – An Engineering Failure
Highway bridges on navigable waterways are at risk from vessel collision. Since they are primarily built to let vessels pass through, design considerations should include the probability of a major collision of its structural members from a passing vessel. There are several factors why vessels may come in contact with a bridge’s structural member. The deviation of a vessel from its path may be caused either by human error, mechanical error or may result because of adverse environmental conditions. Indeed, the collision of M/V Summit Venture with the pier of the Sunshine Skyway Bridge was due to poor vision because of a “blinding spring squall”. It is quite perplexing how the engineers and architects of the original Sunshine Skyway Bridge failed to anticipate such possible scenarios. Prior to 1980, the United States has no specific structural codes regarding vessel collision with any structural elements of a bridge. Although there have been prior incidents of collapse due to collision of vessels on other bridges not only in the U.S. but around the world, the lack of action and foresight on the part of the U.S. engineering authorities can be considered as one of the main reason why the Sunshine Skyway Bridge collapsed on impact with M/V Summit Venture, a phosphate freighter vessel. Since 1960’s, several incidents of ship-bridge collisions in the U.S. have been recorded that has resulted to several fatalities such as in Lake Ponchartain in 1964, Sidney Lanier in 1972 and Pass Manchac in 1976. These incidents should have prompted serious studies regarding the structural integrity of bridges within the U.S. yet authorities failed to do so. In Germany, for example, studies on ship-bridge collisions have been conducted as early as 1970 with the works of Woisin. Japan has also made a similar study with the works of Fuji and Shiobara in 1978 (Manuel et. al., 2006). However, in the U.S., it was not until the Sunshine Skyway Bridge disaster occurred that the American Association of State Highway and Transportation Officials (AASHTO), a U.S. agency that sets the standards for structures, conducted a serious consideration of structural codes to increase a bridge’s structural integrity and prevent collapse in the event of a vessel collision. Aside from the apparent laxity of U.S. engineering authorities, the bridge contractor’s ethical values and integrity is also in question. Andy Nowak, a civil engineering professor in the University of Michigan commented that though it is human to commit errors, it should not be devastating as to become hazardous. Though it is debatable whether the bridge’s contractor committed design errors since, technically speaking, no structural codes regarding how the bridge should be built have been officially issued yet by the time the bridge was being designed. Even so, the eminent possibility of a vessel collision should have been considered. According to Novak, this type of error is intentional wherein the designer already knew that something is wrong with the design yet he pushes through with it.
Lessons Learned
Several lessons can be learned regarding the Sunshine Skyway Bridge incident. First, it showed that failure of government agencies that regulate the engineering profession to conduct a thorough examination of its codes would result in disasters. There was an apparent neglect and lack of foresight on the part of AASHTO in investigating prior incidents of ship-bridge collisions. On the other hand, in the absence of regulations, responsible engineering must take into account human safety. Not only should economic and aesthetic considerations must be employed in bridge designs, most importantly, the factor of safety should be of primary concern. There are times when human error, mechanical error and environmental hazards could not be avoided. However, with the right amount of preparation and prudence, errors can be mitigated and should not result to fatalities.
Could the incident have been avoided?
There are several scenarios that can be conjured that would render Sunshine Skyway Bridge Disaster of 1980 avoidable. The accident could have been avoided with the installation of precautionary measures. One is to increase the structural integrity of the bridge’s pier by taking into account possible vessel collision. This can be done either by exceeding the specifications in the planning stage or reinforcing the existing structure thereby increasing its factor of safety. Another preventive measure that could be employed is to construct protective structures such as artificial islands and guide structures. Aside from preventive measures that should have been employed to protect the bridge, additional fixtures could have addressed visibility issues that would have prevented M/V Summit Venture from deviating on its path. Sufficient lighting underneath the bridge, for example, would have allowed the ship’s captain to see the pier at a safe distance, giving him enough time to steer the ship away from the pier. Even so, accidents do happen and even in the most carefully planned scenarios, errors could not be avoided. Despite human efforts to increase a structure’s safety, there is no assurance that the structure would be 100% safe. For a fact, structures could only be built to withstand a certain magnitude of earthquake that is why most structural engineers avoid using the term ‘earthquake proof’, instead they use ‘earthquake resistant’. And what about tsunamis or super typhoons? Are they not possible threats to a structure’s integrity that could lead to collapse of the structure specifically the Sunshine Skyway Bridge? For the same reason, most builders stick to the existing codes for the sake of practicality and economy. However, what happened in 1980 can still be considered as within the scope of human control. Naturally, someone would have to take the blame. And in this case, it goes out first to the authorities for their lack of prudence, and of course, to the builders for their lack of values.
References
Gucma, L. (2009, June). METHODS OF SHIP-BRIDGE COLLISION SAFETY EVALUATION . Retrieved June 2014, from http://gnedenko-forum.org/: http://gnedenko-forum.org/Journal/2009/022009/RATA_2_2009-05.pdf
Henderson, W.R. (2005, May). Modeling and Analysis of Bridges Subjected to Vessel Impact. Retrieved June 2014, from fsel.engr.utexas.edu: https://fsel.engr.utexas.edu/publications/docs/Henderson,%20Wyatt.pdf
Hostetler, M. (1990, June). The Bridge Between Safety and Error. Retrieved June 2014, from http://deepblue.lib.umich.edu/: http://deepblue.lib.umich.edu/bitstream/handle/2027.42/61120/2202.pdf?sequence=1
Manuel, L., Kallivokas, L, Williamson, E., Bomba, M., Berlin, K., Cryer, A. & Henderson, W. (2006, November). A Probabilistic Analysis of the Frequency of Bridge Collapses due to Vessel Impact . Retrieved June 2014, from http://www.utexas.edu/: http://www.utexas.edu/research/ctr/pdf_reports/0_4650_1.pdf
St. Petersburg Times. (1999). A blinding squall, then death. Retrieved June 2014, from http://www2.sptimes.com/: http://www2.sptimes.com/Weather/SW.2.html
Svensson, H. (2009). Protection of bridge piers against ship collision. Retrieved June 2014, from http://www.inti.gob.ar/: http://www.inti.gob.ar/cirsoc/pdf/puentes_hormigon/sdr561.pdf
