Description Second Narrow Bridge Collapse - Essay Example

Introduction The construction industry faces myriad of challenges when executing their building obligations. According to McGuire (44) mistakes that are committed by the contractors causes losses of varied proportions. Construction workers together with the engineers face many hazards in the work place. Deaths, injuries, project delays and losses of money have formed part of the bitter memories of collapsed building and other accidents in the work place. Stalker and Andrew (157-158) confirmed that the second narrow bridge accident that claimed lives of nineteen people and caused losses when it collapsed is still the worst industrial accident in British Columbia. The cause of accidents in the construction of bridges has been attributed mainly to the error committed during the project design. The errors are caused by negligence in the side of the contractors. The fatalities in the construction industry are caused by failure to comply with the industry’s safety and health guidelines. It is important to adhere to safety and health directives and guidelines to avert future disasters such as the second narrow bridge accident. Description second (2nd) narrow bridge collapse Wienand and Zunde (147-158) confirmed that the second narrow bridge was made of steel metals, timber and reinforced concrete. According to Akesson (124), the construction of new highway bridge in British Columbia began in November 1957. The second narrow bridge had six lanes and was a continuous truss bridge (in all 1992 meter long) with the main 335-navigation span. It was also a cantilever construction having two anchor spans, (142 m each). The second narrow bridge had lanes specifically for the pedestrians and bicycles. It was the second bridge constructed at the Second (east) Narrows of Burrard Inlet in Vancouver, British Columbia, Canada. It was named the Second Narrows Bridge as it connects Vancouver to the north shore of Burrard Inlet, which includes the District of North Vancouver, the City of North Vancouver, and West Vancouver. It was constructed adjacent to the older Second Narrows Bridge, which is currently an exclusively rail bridge. The bridge was a steel truss cantilever bridge, designed by Swan Wooster Engineering Co. Ltd. On June 17, 1958, the north anchor span through failure of the temporary truss, collapsed without warning and caused death of the sixteen workers and two engineers. Description of failure and resulting consequences Akesson (125) said that on the fateful afternoon of June 17, 1958, the crane was stretched to join the two chords of the arch that was under construction from the north side of the new bridge. Just before the accident, many ironworkers were preparing to leave the construction site after a hard day’s work 40 meters above Burrard inlet. As the workers bolted up together the spans on the northern side of the burrard inlet to join the other span on the southern end to connect North Vancouver to South Vancouver, the second narrow bridge collapsed suddenly without warning. The collapse occurred despite the fact that the bridge was supported on both sides. It was discovered that the northern anchor span collapsed due to failure of the temporary truss which had been erected to support the bridge. When the northern anchor collapsed, the adjacent span over the burrard inlet lose its support as the pier was pulled away causing the unpredicted collapsed. Consequently, second narrow bridge came tumbling down into the water. The workers who were busy putting in the bolts and inserting huge nuts on the bolts inside together with the huge heavy beams felled into the water. During the collapse, there was a heavy bang similar to that from high power gun as the bolts and splices banged off. Seventy-nine workers fell abruptly 30 meters (100 ft) into the water. Eighteen workers, among them two engineers perished on the fateful day. Furthermore, the collapse caused extensive damage to the second narrow bridge and thousand of debris plunged into the waters. The accident was inscribed into the memories of people who witnessed the whole episode. The fall of the ironworkers, two engineers and the painter was a nightmare because they crashed into the debris from the collapsed bridge. Consequences The collapse of the second narrow bridge caused so many losses. First, nineteen people lost their lives and several were injured when they fall together with the debris into the water. Fifteen ironworkers lost their lives, three engineers, a painter, and a commercial diver. The commercial diver died when he drowned days after the accident as he tried to retrieve the body of a dead man. There were several people who were injured. The scene was marred with people with the broken arms, bruised bodies and massive internal body injuries. It was like watching a scene of horror. The people who witnessed the accident were deeply disturbed psychologically. After the accident, women become widows and children lost their fathers. Furthermore, the affected people lost means of livelihood after those whom they depended upon for food and other basic necessities died in the accident. The people who survived the ordeal sustained permanent injuries and are not able to use they expertise as before. The accident was the largest number of worker fatalities in one industrial incident in the history of British Columbia.  The government and contractors lost money as a result of the damage caused by the collapse. The completion of the second narrow bridge was also delayed. The company that was given the tender to construct the second narrow bridge suffered credibility crisis because of the collapse of the bridge under construction. Finally, the department foreseeing the construction industry made the construction rules more stringent to prevent further occurrence. Likely causes of failure After the accident, British Columbia government appointed a committee to investigate the causes of the accident. The committee was made up of five leading engineers selected to investigate and give a report on the likely causes of failure. Investigations and testing of materials was done at the University of British Columbia and Vancouver laboratories. According to Great Britain advisory committee on false work, the second narrow bridge collapsed due to two main reasons. The error in design and negligence on the part of the engineers caused the collapse of the bridge. The laboratory tests showed that the building materials used met the minimum requirements. Consequently, the causes narrowed on the engineering design calculations. A young and inexperienced engineer was given a task to calculate the grillage and in the process made the calculation error. According to institution of civil engineering (34-36) two key mistakes that the young engineer did were basing the calculation on the cross sectional area of the whole beam instead of on the areas holding the load. The second mistake that the young engineer did was the wrong calculations on the web stiffeners. Therefore, the two errors misled grillage designer to judge the beam’s strength to be twice as much as its real ability. As a result, the contractor engineers used one-inch thickness of the beam flanges instead of the required 0.65-inch web thickness. The above results indicated that stiffeners were not necessary. However, Jones (96) confirms that stiffeners were supposed provide extra support and resistance to the buckled beam webs and metal plates welded to it. The temporary columns with faulty designs caused malfunctioning of the four upper grillage beams causing the collapse of the bridge. The collapse was thus blamed on the poor design of the grillage beam that was suppose to the load in its vertical plane to prevent the stress from tearing the beam vertically at the pint of the concentrated load. The young and inexperienced engineer who made the calculations error was to blame. Unfortunately, the engineer succumbed to the injuries. The blame also extended to other contractor engineers who failed to provide adequate supervision and guidance to the young engineer. The other likely cause of failure was negligence. According to the results of the investigations, it became evident that the contractor does not have sufficient quality assurance testing. This is because the engineers could not discover the error on time. There seems to have been some laxity during the construction process because a report from Dominion Bridge Company indicated that the error has been discovered earlier before collapse but no corrective action was taken. How failure could have been prevented The second narrow bridge accident which is the worst industry accident in the history of British Columbia could have been prevented if the contractor engineers would have followed the professional code of ethics and safety and health regulations of the construction industry. According to Silano and Parsons (798), engineers have the duty to anticipate possible failures and prevent it from occurring. This could have been done by reexamining the work that was done by the young and inexperienced engineer. The experienced engineers should not have left the young engineer with the full discretion to make such a mathematical decision. In addition, the experienced engineers should have rectified the mistake earlier. Blockley (593) conquers and adds that the engineers have the competence and expertise to design and modify the structures in order to surpass the minimum requirements that have been universally set. The experienced engineers have proven track record of success because they have learned from passes mistakes and success. The second way that the collapse could have been avoided is by developing a proven system that helps to identify errors that are made. There is a popular belief that man is to error. Therefore, it is possible for experienced engineers to err in making their judgments as the young and inexperienced engineers. According to Ching and Winkel (48-50) contractors should develop a system of testing and evaluating key decisions that are made by engineers concerning the construction projects. This should be done before the constructions begin. Through the above approach, the mistakes would be minimised and accidents reduce. Furthermore, Lacasse et al (436), confirms that the construction process does not end with the specification; the contractors should ensure that all the specifications are followed keenly. The engineers should develop monitoring mechanisms that help to track changes from the planned specifications so that errors could be discovered and remedial actions taken. According to Ryall (56) effective communication should be integrated into the construction process. This is because poor communications among the employees in the company may lead to errors. Finally, Raina (49-50) adds that the construction company should employ competent engineers to foresee general construction efforts. The experienced engineers should be encouraged to mentor the young and inexperience engineers. The company should ensure that all employee pass through the safety and health training before commencing the projects of the company. Conclusion Hale et al (53-54) confirmed that decision came up in 1955 to construct a six-lane high-level highway bridge, its approximate cost was between$12 million to $15 million, and had construction period of three years. Its length was 1,292 meters and was to be the longest cantilever bridge in Western Canada, and the eighth longest in the world. Andrews (281-290), confirms that in June 1958, groups of workers were busy constructing the sixth span of the bridge. However, the bridge collapsed suddenly into the water when the spans front end sagged downwards and drove the partially completed span into Burrard inlet. The falling metalwork pulled the permanent pier it was resting on out of line and caused the adjacent approach truss to collapse. Several workers were thrown into the water as others were dragged down into the wreckage. The consequences were severe because nineteen people perished on the spot. Those who survived the accidents broke their arms and legs, hurt their backs and suffered extreme internal injuries. According to White et al (57), the cause of collapse was a mathematical grillage error made by a young and inexperienced engineer that led to wrong assumptions afterwards. Negligence on the part of the contractor engineers was also cited because the error was realized earlier but was not rectified. According to Chuck (798), engineers should be keener and are supposed to anticipate possible design failures and prevent it. The second narrow bridge was renamed Steelworkers Memorial Bridge during its opening in 1960. Work cited Akesson, Bjorn. Understanding Bridge collapses.USA, US: CRC Press, 2008. American Society of Civil Engineers. Structural Division. Journal of the Structural Division.USA, US: University of Michigan, 1960 Andrews, C. G. Canadian Professional Engineering and Geoscience: Practice and Ethics.4th edition, USA, US: Cengage Learning, 2008. Blockley, David. Bridges: the Science and Art of the World are Most Inspiring Structures. Oxford, UK: Oxford University Press, 2010. Ching, Frank and Steven Winkel. Building codes illustrated: a guide to understanding the 2006 International building code. 2nd edition, USA, US: John Wiley and Sons, 2007. Chuck, Davis. The Vancouver book. Canada, J. J. Douglas, 1976. Great Britain. Advisory Committee on False work. Final report of the Advisory Committee on False work. Britain, UK: H.M.S.O., 1976. Hale, Louise Linda and Frances Woodward andVancouver historical society. Vancouver centennial bibliography: a project of the Vancouver Historical Society, Volume 2. Canada, Vancouver Historical Society, 1986. Institution of Civil Engineers (Great Britain). Proceedings of the Institution of Civil Engineers: Design and construction. Britain, UK: Institution of Civil Engineers, 1976. Jones, Robert. Buckling of Bars, Plates, and Shells. Virginia, Bull Ridge Corporation, 2006. Lacasse, Michael and Dana Vanier. Durability of Building Materials and Components 8: Service life and durability of materials and components. Canada, NRC Research Press, 1999. Silano, Louisa and Parsons Brinkerhoff. Bridge inspection and rehabilitation: a practical guide. USA, US: Wiley-IEEE, 1993. McGuire, William. Steel structures, Part 4. USA, US: Prentice-Hall, 1968. Nicol, Eric. Vancouver. Canada, Doubleday Canada, 1978. Raina, K. V. Concrete bridges: inspection, repair, strengthening, testing and load capacity evaluation.USA, US: McGraw-Hill Profession, 1996. Ryall, J.M. Bridge management. Oxford, UK: Butterworth-Heinemann, 2001. Stalker, Aileen and Andrew Nolan. Sea Kayak Paddling Through History: Vancouver & Victoria. Canada, Heritage Group Distribution, 2005. University of Michigan. Engineering news-record. USA, US: McGraw-Hill, 1958. White, Kenneth and John Minor and Kenneth Derucher. Civil and Environmental Engineering.USA, US: CRC Press, 1992. Wienand, Norman and Joan Zunde. Materials, specification and detailing: foundations of building design. Oxford, UK: Oxford Routledge, 2008. Read More