Collapse Of The Quebec Bridge 1907: Causes, Incident, And Effects

Discuss about the Collapse of the Quebec Bridge 1907.

The needs of Quebec for the transportation resulted in the proposal of building bridge in St. Lawrence River. It is considered that the Quebec Bridge was one of the longest cantilever structures that was attempted to build in that period of time. At the time of the final design of the bridge, it was 548.6 m long. The project of the building the bridge was troubled from the initial stages due to the financial resources. This caused hindrance in the construction and the design of the bridge. The construction of the bridge started in 1900. The collapse of the bridge suddenly took place in August 1907. In the accidents 75 workers were killed and only 11 workers survived. A panel was assembled for the investigation of the disaster. It was found in the report of the panel that the major cause of the failure of the collapse of the bridge was the inappropriate design of latticing upon the compression chords. The collapse of the bridge began by Chord A9L’s buckling failure upon anchor arm which was near pier, instantly afterwards Chord A9R. The consulting engineer for the project of Quebec Bridge was Theodore Cooper and he was blamed for the collapse of the bridge. He permitted for the high allowable stress; As a result, he failed to recalculate the dead load on the bridge when span of the bridge was lengthened (Pearson & Delatte, 2006).

Main channel for the purpose of the trade for Quebec was St. Lawrence River at the time of summer. At the time of winter, the river filled with ice and due to this the people were not able to trade. The need of the people of Quebec to become competitive was the reason behind the building of the bridge upon the river. The length of the initial design of the bridge was 487.7 m. In May 1900, the length of the bridge was increased to 548.6 m by the consulting engineer Theodore Cooper. It was mentioned by Cooper that this will help in eliminating the risk of the construction of piers in deep water, reduce the time of construction of piers and reduce the effect of ice. The engineering reasons were genuine for the change in the plan for the construction of the bridge. The construction started on 2^nd October 1990. The Quebec Bridge Company had sufficient funds to start erecting the substructure. The supervisors and the workers found deflections on the chords of the bridge when the bridge was erected. At the time when the workers put efforts to rivet the joints in between the chords, the line up of the predrilled holes was not possible. Apart from this, the deflections in the bridge were also noticed in compression members. By the time, the deflection in the compression members increased. In mid June, the deflections were noticed and reported to Cooper by the site inspector. The cambering of the compression members had been done to line up the joints and rivet together. Although, some joints failed to close. It was presumed by the inspector and the Cooper that the small deflections in the bridge took place because of some unidentified pre-existing condition and they were not worried. Later, other deflections were also found during the inspection in the chords in August. Again the deflections were reported to Cooper. He messaged to chief engineers of Phoenix Company asking about the bend in the 7L and 8L chords. It was replied by chief engineer that he did not know. Chief design engineer of Phoenix Company was sure that bend was put at shop in the chord ribs. Later, it was admitted by him that he never questioned the chords. On site inspector justified that he was sure that the bend in the chord occurred when the chords were under stress and he was not there at the time when the chords were positioned. Another bend in the chords 8L and 9L was reported to Cooper (Modjeski, Borden, & Monsarrat, 1919). The lower chords of truss were deflecting on either side of pier. An unusual patter was emerging in the bridge. Compression member with the heavy loads were steadily bulking. The latticing in the compression members were building and the higher stresses were placed upon latticing and upon the rivets attached to lattices.

Action taken to handle situation

Site engineers offered the theories to Cooper but he was dissatisfied by the theories. Hence he developed a theory on his own.  Cooper instructed McLure and as ked for reporting back. McLure found no such evidence of an incident. Some engineers were not concerned about the problem and some insisted to the fact that the bend in the chords were due to pre-existing conditions. The manufacturers guaranteed that the chords were perfect at the time of delivery of them from the shop (Holgate, Derry, & Galbraith, 1908). An incident also occurred in the construction season as the chord was dropped and bent at the time of handling. It was repaired and put in the structure. At that time the repair was satisfactory and later it was became the cause of collapse.

Cooper was old and never visited the site for the review after the initiation of the construction. He was only consulting on the basis of the information we was receiving from the site inspector. Later the deflection increased in the chords. The construction work was stopped by foremen at that time for the review of the matter. The chief engineer of Quebec Bridge Company again resumed the work and it was stated by chief engineer that the load on the chord members were less than the maximum load. McLure and Cooper were not aware about the restart of the construction. A meeting was held to decide the action (Petroski, 1995).

At the day of meeting, 10 km away, a thunderous roar of collapse was noticed in Quebec. The whole of the south half of bridge fell in the river in 15 seconds. At that time 86 workers were there and out of them only 11 workers survived. The bottom compression chord was not able to stand due to bent and increased weight of bridge. The load transmitted to the opposite chord. Only buckled part was survived. 33 ironworkers were killed and 2 were injured. 

In order to handle the situation at the time of the deflections in the chord, the multilayer ribs were stiffened by diagonal latticing so that it could act as one. At the time of the testing, the lattice system failed because of shearing of rivets after the buckling of chord. The deflections in the chord was the concern of the foremen hence, they stopped the construction work at that time and decided to keep the work on hold to resolve the matter. But the construction work was resumed and the meeting was called in order to make decision to take the right action (Tarkov, 1986). Although no such effective was noticed at that time and the increased differences in the chord resulted in the collapse.  

Effect

In this incident of collapse of the bridge, 75 workers were killed and only 11 workers survived. Out of the total workers 33 ironworkers were killed and 2 were injured. Many laws of ethics were also broken. The collapse resulted in the loss of lives of 75 workers.  This incident of collapse put pressure to test and study the compression members. The testing resulted in key advancement in the area of engineering. The bridge specifications were enhanced after this incident of collapse (Lockett, 2018). The two of the organizations were emerged in the field of engineering and provided with the support to fund the research as it was difficult for the or the fabrication companies to conduct by their own. 

As per the report by Royal Commission, the main cause of the collapse was buckling of the compression chords A9R and A9L.  The failure of lower chord in anchor arm near main pier was the reason of the collapse of Quebec Bridge. The defect in the design was the reason for the failure of the chords. Apart from this, the failure was also on part of Railway Company and Quebec Bridge Company as they appointed the bridge engineer as the chief engineer. This resulted in ineffective and loose supervision (Middleton, 2001). Mainly the errors were in the design. Along with this, Cooper had not visited to the site after the initiation of the construction work.  On the other hand, the assumed dead loads and the actual dead loads were different and there was a fundamental error in calculation for bridge. After the increase in the span the stresses were not recalculated. The negligence of the professional procedures, short of the financial resources and time constraints can be considered as the cause of the collapse (Roddis, 1993). The failure in all these areas resulted in the collapse of the bridge into the water

The plan for building the Quebec Bridge was developed in order to provide the ease to the people of Quebec for carry out the activities related to trade. It was difficult for the people to trade at the time of winter due to the ice. The stakeholders of the bridge project were Quebec Company, Phoenix Company, Cooper, Szlapka and the other engineers, government and the public. Cooper was appointed as the consulting engineer for ten bridge project. On-site engineers offered theories to Cooper but he was not satisfied with their theories hence Cooper developed his own theory. He developed the design for the Quebec Bridge. Initially the span length of the bridge was 487.7 m but later the designed for the bridge was redeveloped and the final span length of the bridge was 548.6 m. Cooper stated that, it will help in reduce the time of the construction of the piers and will also help in reducing the uncertainty in the construction of piers in the deep water and will also help in reducing the effect of the ice. The erecting of the bridge began and in the initial stage of the construction work of bridge, the deflections were noticed by the workers and the supervisor. When the workers put their efforts to fix the joints in between the chords, they were unable to line up the predrilled holes. The deflections were also found in the other compression members which were loaded with heavy weight. Later the deflections in the chords increased. There was defect in the design of the bridge and later, other deflection came up in the other chords of the bridge. It was communicated by the site engineer to Cooper but it was assumed by him that these deflections are small and it was neglected. Later it was stated by Site engineer of Cooper that the deflections were there in the chords when it was handled. The chords with heavy loads were bulking. It was stated by chief engineer of Phoenix Company that there was bend in chord ribs at shop and it was repaired and used in the bridge.  The foreman on the construction site later stopped the construction work of bridge. The work was resumed by chief engineer of Quebec Company and Cooper and McLure was not aware about this fact. At the time of the meeting, the bridge collapse. The reason for the collapse was lack of time, financial resource, the negligence to the deflections in the chord of the bridge, errors in the design of bridge, lack of cooperation and supervision and breaking the laws or not following the professional procedures. The collapse of the bridge resulted in the death of 75 workers and only 11 workers survived.  It is important for the engineers to develop effective and efficient design and should not neglect the problems that occur during the construction work. It is the responsibility of the involved companies and the engineers to review the construction work and follow all the professional procedures in proper manner. It is also important to make sure that that the right actions are taken for the reducing or eliminating the problems

Holgate, H., Derry, J. G., & Galbraith, J. (1908). Royal Commission on Quebec Bridge Inquiry Rep. Quebec Bridge Inquiry Report S. E. Dawnson.

Lockett, W. G. (2018). The Lesson of the Quebec Bridge. Scientia Canadensis, 11(2), 63–89.

Middleton, W. D. (2001). Bridge at Quebec. Ind.: Indiana University Press.

Modjeski, R., Borden, H. P., & Monsarrat, C. N. (1919). The Quebec Bridge over the St. Lawrence River. Rep. of the Government Board of Engineers. Canada: Canada Department of Railways and Canals.

Pearson, C., & Delatte, N. (2006). Collapse of the Quebec Bridge, 1907. Journal of Performance of Constructed Facilities, 20(1), 84-91.

Petroski, H. (1995). Engineers of dreams: Great bridge builders and the spanning of America. New York: Knopf.

Roddis, W. M. (1993). “Structural failures and engineering ethics.”. Journal of Structural Engineering, 119(5), 1539–1555.

Tarkov, J. A. (1986). “A disaster in the making.”. American Heritage of Invention and Technology,, 1(3), 10–17.