Demers et al. v. Dufresne Engineering Co. Ltd. et al.

Demers et al. v. Dufresne Engineering Co. Ltd. et al.
Collection
Supreme Court Judgments
Date
1978-10-03
Report
[1979] 1 SCR 146
Judges
Ritchie, Roland Almon; Pigeon, Louis-Philippe; Dickson, Robert George Brian; Beetz, Jean; Pratte, Yves
On appeal from
Quebec
Subjects
Contract
Decision Content
Supreme Court of Canada
Demers et al. v. Dufresne Engineering Co. Ltd. et al., [1979] 1 S.C.R. 146
Date: 1978-10-03
Lucille B. Demers, Claude Demers and Jacques Desnoyers, co-executors of the Estate of the late Georges Demers (Defendants) Appellants;
and
Dufresne Engineering Company Limited and McNamara (Quebec) Limited (Plaintiffs) Respondents.
1977: November 9 and 10; 1978: October 3.
Present: Ritchie, Pigeon, Dickson, Beetz and Pratte JJ.
ON APPEAL FROM THE COURT OF APPEAL FOR QUEBEC
Contracts—Construction of bridge—Damage resulting from an error in the method of performance—Fault of the contractor—Liability of the engineer in charge of the work—Stipulation for the benefit of a third person—Civil Code, art. 1029.
In 1962, the Corporation du pont de Trois-Rivières (the owner) retained the services of the late Georges Demers (the engineer), whose executors are the appellants, to prepare the plans and specifications for and supervise the work on the bridge project. In 1965, the owner awarded respondents (the contractor) a contract for the construction of the bridge piers. In the course of the work, a caisson exploded under pressure of the compressed air and the contractor had to rebuild it at a cost of $1,400,000. This is the amount which the latter is claiming from the engineer. The Superior Court dismissed the action, while the Court of Appeal held the engineer one-third liable. Both parties are appealing against the decision.
The facts showed that the explosion of the caisson was due to a glaring error in the contractor’s method of performing the work. This method was not included in the plans but had been used by the contractor in the performance of an “alternate project”.
Held (Pigeon J. dissenting): The appeal should be dismissed and the cross-appeal allowed in part.
Per Ritchie, Dickson, Beetz and Pratte JJ.: Under a contract between the owner and the engineer, the latter had absolute authority as to the method of performing the work. The contract between the owner and the engineer contained a stipulation for the benefit of a third person under which the engineer was to provide the contractor with information, advice and instructions the latter needed in carrying out the work. By being given complete authority over the work, the engineer was expected to exercise his power of general control like a competent and diligent professional. The role of the engineer cannot be reduced to an essentially passive role and it cannot be concluded that he had an obligation toward the contractor only if the latter formally asked him for advice.
In the case at bar, the explosion of the caisson resulted from an erroneous method of performance which the engineer was aware of. If he had not been aware of it, he ought to have been since this was such an enormous error. By remaining silent, the engineer implicitly approved the work method chosen by the contractor. Moreover, he also implicitly approved the minor alteration suggested by his representative, which was obviously inadequate. By committing these two errors, the engineer effectively allowed the work to be performed incorrectly, and this caused the accident. By failing to carry out his contractual obligation, resulting from the stipulation for the benefit of a third person, the engineer became liable toward the contractor. However, the fault of the engineer does not have the effect of relieving the contractor of all liability. The fault of one is as great as the fault of the other and liability should be shared equally between the two parties.
Per Pigeon J., dissenting: There can be no liability of the engineer under arts. 1053 or 1688 C.C. because the accident was not caused by faulty design of the work but solely by a bad work method adopted by the contractor. The only possible source of liability toward the latter is therefore the stipulation for the benefit of third parties in the contract between the engineer and the owner. This stipulation did not oblige the engineer to go to the contactor and instruct him to avoid any error in his own area of responsibility: the method of carrying out the work. If the contractor chose not to ask him for advice, the engineer was not obliged to give any. The engineer’s representative on the work site went beyond what the engineer was obliged to do and committed no fault in giving correct information, even though he did not then see that his observations were followed by orders designed to remedy the inadequacy of the precautions that the contractor was taking. In respect of the professional services contemplated therein, the stipulation for the benefit of third parties obliged the engineer to “await orders” from the contractor not to issue any.
[Bélanger v. Montreal Water and Power Co. (1914), 50 S.C.R. 356; Vermont Construction Inc. v. Beatson, [1977] 1 S.C.R. 759, referred to; Bilodeau v. Bergeron et al., [1975] 2 S.C.R. 345; Davie Shipbuilding et al. v. Cargill Grain et al., [1978] 1 S.C.R. 570, distinguished.] APPEALS from a decision of the Court of Appeal of Quebec[1] reversing a judgment of the Superior Court. Appeal dismissed, cross-appeal allowed in part, Pigeon J. dissenting.
A.J. Campbell, Q.C., and John J. Pepper, Q.C., for the appellants.
Guy Gilbert, Q.C., and Pierre Magnan, for the respondents.
The judgment of Ritchie, Dickson, Beetz and Pratte JJ. was delivered by
PRATTE J.—I have read the reasons of my brother Pigeon J., but contrary to him I am of the view that the appeal should be dismissed and the cross-appeal allowed.
The facts are set out clearly by Pigeon J., and it is unnecessary for me to relate them again.
The main issue raised by this appeal is as to the extent of the obligations of the engineer Demers (the engineer) toward respondents (the contractor) under a stipulation for the benefit of a third party contained in the contract between the engineer and the Corporation du pont de Trois-Rivières (the owner); in brief, the question is whether there existed such a stipulation for the benefit of a third party and if so, what was its scope.
A stipulation for the benefit of a third person does not require that the parties use a set formula, any more than it results from the mere fact that a contract may benefit a third person; it exists when the parties intended to confer a right on the third person. There can be no stipulation for the benefit of another if the parties did not intend to stipulate for another, but only for themselves. The existence of a stipulation for the benefit of a third party thus depends essentially on the intent of the parties. In some cases this intent is manifested clearly; this is the case “where the parties formally stipulate that the debtor is obligating himself for the benefit of a third person” (Mazeaud, Leçons de droit civil, Tome 2, Vol. 1, No. 778, at p. 797). In other cases the stipulation is not expressly stated in the contract and the intent to stipulate for the benefit of another is only implicit; it flows from the interpretation given to the contract by the Court in the light of all the circumstances. In such a case the existence of the stipulation for the benefit of a third party is properly a matter of contract interpretation. Whether there existed the necessary intent to make a stipulation for the benefit of a third party must be determined in accordance with the ordinary rules governing the interpretation of contracts (Weill, Droit civil, les obligations, 1971, No. 532, at p. 561). In Bélanger v. Montreal Water and Power Co[2]. Anglin J., as he then was, said at p. 366:
But every contractual stipulation for the benefit of another (stipulation pour autrui) does not give to that other a right of action to enforce it. Such a right arises only where it was the intention of the parties to the contract to confer it—an intention the existence or non‑existence of which must be determined by the interpretation of the contract.
The scope of a stipulation for the benefit of another must of course be determined in the same manner: it is a matter of ascertaining the intent of the parties by resorting to the ordinary rules of construction.
As regards the case at bar, two preliminary observations should be made: first, although the engineer and the contractor were third parties with respect to each other in the sense that they were not, except for the stipulation for a third party, contractually bound to one another, they were nevertheless not strangers (Vermont Construction Inc. v. Beatson[3], per Pigeon J., at p. 768); both were bound to the owner by two separate contracts that obligated them to be constantly in contact with one another with a view to a common purpose: the construction of the planned work (Soinne, La responsabilité des architectes et entrepreneurs après la réception des travaux, Vol. 2, at p. 635). These two contracts should therefore be given the interpretation that is most likely to ensure the achievement of this goal. In the absence of clear indications to the contrary, it must be assumed that the parties intended to stipulate so as to facilitate rather than impede the carrying out of the purpose that was common to the two contracts. In ascertaining whether there was an intent to stipulate for the benefit of a third party it seems to me quite legitimate to take these factors into account; the contractor was not a third party like any other in relation to the engineer; the contractor and the engineer were united in the pursuit of a common goal.
If we now examine the contract between the owner and the engineer, it is clear that the latter had greater authority and responsibility than that of an ordinary “maître d’œuvre”. He was not only responsible for constructing and supervising the project, but he also had absolute authority as to the method of performing the work. The following specifications in the contract are worth noting:
[TRANSLATION]
1. Retention of the engineer’s services
(a) The corporation shall retain the services of the engineer, who undertakes to provide them, for carrying out the mandate and work of a professional engineer necessary for completion of the project, more fully described in the following clauses.
…
5. Supervision of the work
As soon as the corporation informs the engineer in writing that it has awarded one or more contracts respecting the construction, the latter shall assume full and complete supervision of the work on the project until it is completed; he shall be responsible for ensuring that this work is in accordance with the plans and specifications approved by the corporation.
…
11. Construction methods and schedules, etc., of the contractors and subcontractors
The engineer shall examine the construction methods and schedules proposed by the contractors and subcontractors; he shall be responsible for verifying and approving their construction drawings and their shop drawings.
…
14. Information, advice and instructions
He shall make himself, or his engineers and technicians, available at all times to the corporation, the contractors and the subcontractors in order to provide them with the information, advice and instructions they need in carrying out the work.
…
16. Co-ordination of the work
He shall be responsible for co-ordinating the work of the various contractors and subcontractors with a view to ensuring that the construction progresses smoothly and rapidly.
…
18. Quality of the materials, etc.
He shall be responsible for controlling the quality of all the materials and of the labour and ensuring that the construction is in accordance with accepted practice.
…
20. Recommendations, concerning work and materials; final revised plans
He shall make recommendations to the corporation, contractors or subcontractors, as the case may be, for accepting or rejecting the work and materials; when the work has been completed he shall provide the corporation, where necessary, with the revised plans and specifications for the project as carried out.
…
22. Presence in Trois-Rivières and on the site
Throughout the duration of the construction work the engineer shall maintain an office in Trois-Rivières or within a radius of five (5) miles of the limits of that city; he himself or his representatives shall be present on the site in order to more effectively ensure that his obligations under this contract are fulfilled, especially with respect to supervision of the work and of the material and machine testing on the site.
Concerning the contract between the owner and the contractor, several provisions in the specifications that were prepared by the engineer and that were part of this contract confirmed the contractor’s complete subordination to the engineer with respect to the manner of performing the work, an area normally reserved to the contractor:
[TRANSLATION]
3. PLANS AND SPECIFICATIONS
The work to be performed is set out in the specifications and indicated on the plans prepared by Geo. Demers, Consulting Engineer, Quebec City, and numbered as follows: The plans and specifications for the contract also include any additional plans or specifications that might be issued as an addendum to those herein described in order to alter, increase or decrease the construction method or the nature, quality or quantity of the construction work to be performed.
…
The tenderers may, if they wish, submit an alternate proposal for constructing the caissons, together with drawings and a detailed description, but it is understood and agreed that they must submit a price for the project set out in the present specifications and shown on the plans in order for their tender to be considered. After the contract has been awarded, if the alternate project is worthy of consideration the contractor shall submit to the engineer for approval detailed plans with complete calculations for this alternate project.
…
6. SCHEDULES AND CONSTRUCTION DRAWINGS
The contractor shall order the steel for the caissons within ten (10) days following the date on which the contract is signed. Before the work is begun, the contractor shall submit to the engineer, for approval, a work schedule and the construction drawings required for construction of the four (4) caissons and piers. The schedule and construction drawings shall be accompanied by a permit from the Department of Transport stating that the work can be carried out as planned without objection and in accordance with the river navigation regulations.
7. WORK METHOD
The contractor shall submit in writing to the engineer the work method he intends to use and indicate where he proposes to construct the caisson parts that are to be built away from the bridge site. The engineer alone shall be free to accept or reject this method. The contractor alone shall be responsible for any delay or increase in cost that may result from the rejection or the adoption of a particular work method for carrying out any part or the whole of the project.
8. ALTERATIONS
No alteration to the project or to the materials specified shall be accepted without written authorization from the engineer and the Corporation. In the event the contractor carries out such work altering the project or the materials specified without the authorization of the engineer and the Corporation, he shall demolish it, remove it and redo it, or replace it according to the plans and specifications, at his own expense, and shall not be entitled to any compensation of any kind whatsoever for having proceeded in this manner.
In addition, the original plans and specifications prepared by the engineer set out in detail the way in which the work was to be performed, from which the contractor could not deviate without the engineer’s permission.
In light of these various contractual provisions, can it be said that the engineer contracted obligations toward the contractor, and if so, what was their extent?
It is, in my view, indisputable that the contract between the owner and the engineer contained a stipulation for a third party that is expressly set out in clause 14 which reads as follows:
[TRANSLATION]
14. Information, advice and instructions
He [the engineer] shall make himself, or his engineers and technicians, available at all times to the corporation, [the owner], the contractors and the subcontractors in order to provide them with the information, advice and instructions they need in carrying out the work.
The scope of this provision must be determined having regard to the terms it contains, the hierarchical and professional situation of the parties as regards one another, and the common goal that was pursued.
This stipulation, it should be noted, obliged the engineer to provide the professional services the contractor needed, not only those asked for by the contractor. The obligation to provide professional services was not dependent upon the contractor’s discretion; the services were due if they were objectively necessary to ensure that the work was performed in a good and workmanlike manner. An objective rather than a subjective test must be used to determine whether the engineer’s professional opinion was required; the criterion is the need for guidance in order to ensure that the work be completed successfully. The intent was to make sure that the contractor would not perform the work incorrectly; the engineer was obligated to intervene whenever he knew or ought to have known that the contractor was not carrying out its work in a good and workmanlike manner. This obligation was all the more imperative where the contractor’s error was manifest. A contractor who adopts a clearly improper work method that will necessarily lead to disaster is demonstrating an incompetence which the hierarchical authority conferred upon the engineer is specifically designed to remedy; he is showing beyond any doubt that he needs guidance from a professional, namely the engineer.
This interpretation of clause 14 seems to me to be the preferable one since, not only is it consistent with the wording of the clause, but it is also perfectly in accord with the authority conferred upon the engineer. The latter was not only responsible for designing the project and supervising the work; he also had authority in an area that is ordinarily reserved to the contractor, namely the performance of the work, over which he had general control; the method of performance of the work was subject to the engineer’s approval.
If the engineer’s authority was this complete, it was obviously because it was felt that the complexity of the technical problems, even at the level of the carrying out of the work, required the professional ability of an engineer. This necessarily implied, in my view, that the parties wanted the contractor to benefit from the engineer’s expertise, since it was on account of this expertise that the latter was given such extensive authority. This also implied, consequently, that the contractor was entitled to rely on the engineer exercising his power of general control like a competent and diligent professional so as to ensure that the construction of the project would be carried out in a good and workmanlike manner.
It is not disputed that the engineer would have been liable toward the contractor if he had given it erroneous advice; I do not see how the situation can be any different where the engineer has approved a similarly erroneous work method. In both cases there is professional fault on the part of the engineer, and this fault, in view of the contractual provisions as well as the engineer’s hierarchical authority and professional status, is committed towards the person who asks him for the advice or approval; in both cases the fault results in faulty performance of the work by the contractor. It was precisely in order to avoid such an occurrence that the contractor was placed under the authority of the engineer. In giving his approval the engineer was accepting responsibility for the method proposed by the contractor; in so doing, he was giving professional advice, he was expressing the opinion that the proposed work method was sound. If he was wrong, he committed a fault towards the person to whom he gave this advice, that is, the contractor. The contrary view has the effect of depriving the engineer’s approval of any real significance and of sanctioning the latter’s irresponsibility. If the engineer’s erroneous approval does not make him liable toward the contractor, it will always be the latter which will in the end have to bear the consequences of the error, since the engineer who is sued by the owner as a result of an erroneous approval he has given, will always have the right to be indemnified by the contractor. Such a result is unacceptable to me. If the engineer has agreed to have the last word concerning the choice of the work method, it is normal that he should be liable to the person over whom he has authority if he allows the latter to proceed in an incorrect manner.
I therefore cannot accept the restrictive interpretation of clause 14 put forward by appellants, whereby the engineer had an obligation toward the contractor only if he gave it advice which the latter had formally requested. Such an interpretation does not seem to me to be consistent with the wording; it disregards the context; it does not take into account the complete subordination of the contractor to the engineer’s authority in the carrying out of the work; it reduces the engineer to an essentially passive role that is not in keeping with his professional status and that is not likely to ensure that the work planned is carried out, although this is the common goal of all the parties.
In support of their submissions, appellants have cited the decisions of this Court in Bilodeau v. Bergeron et al.[4] and Davie Shipbuilding et al. v. Cargill Grain et al.[5]. In Bilodeau the issue was whether a supervisor whose services had been retained by the general contractor to verify the quality of the concrete supplied by a subcontractor had assumed a contractual obligation toward the latter. This Court came to the conclusion that the obligation to supervise had been assumed only toward the general contractor and not toward the subcontractor; it was held that the wording of the agreement between the general contractor and the supervisor precluded a finding that there was a stipulation for the benefit of a third party in favour of the subcontractor, the supplier of concrete. The agreement between the general contractor and the supervisor did not in fact contain any provision similar to clause 16 which is found here in the contract between the owner and the engineer. Furthermore, the supervisor did not have general control over the work and was far from having an authority as broad as that of the engineer in the case at bar. Bilodeau therefore cannot be relied upon in support of appellants’ position.
As regards Cargill, I can see nothing in this decision that can assist in determining whether a contract contains a stipulation for the benefit of a third person, and what is the scope of the stipulation. Further, in my opinion, this decision confirms the view that a person who, because of his authority and expertise, is in the position to carry his point on those with whom he is dealing must assume responsibility for his actions.
I am therefore of the opinion that under this stipulation for the benefit of a third person the engineer had a contractual obligation toward the contractor not to approve, even implicitly, a method of carrying out the work that was clearly erroneous and that could only end in a tragedy.
The explosion of the caisson was due to a glaring error in the method of performing the work that was selected by the contractor; having failed to take the low resistance of concrete in tension into account, the latter did not provide for the use of vertical reinforcing steel. The engineer was aware of this incorrect method of doing the work; if he had not been aware of it, I would have had no hesitation in saying that he ought to have been since this was such an enormous error. By remaining silent, the engineer implicitly approved the work method chosen by the contractor. Moreover, he also implicitly approved the minor alteration which consisted in adding a small quantity of vertical reinforcing steel and which, even having regard to the preliminary calculations made by his representative, the engineer Forgues, was obviously inadequate. By committing these two errors the engineer effectively allowed the work to be performed incorrectly, and this caused the accident. The contractor’s error indicates how much he was in need of the engineer’s guidance in order to perform the work properly; this need for guidance gave rise to the engineer’s obligation to give it to the contractor, to see, in short, that the error be corrected. By failing to carry out this contractual obligation, the engineer became liable toward the contractor. In view of this finding it is not necessary for me to decide as to the engineer’s liability under arts. 1053 and 1688 C.C.
The fault of the engineer, however serious it may be, does not however have the effect of relieving the contractor of all liability. The latter made a first glaring error by failing to take into account the low resistance of concrete in tension; he made a second one, just as serious, by not paying sufficient attention to the remarks of the engineer’s representative, who told him of his concern regarding the caisson’s ability to resist the pressure of compressed air. Mayrand J.A. of the Court of Appeal was correct in saying that the contractor was guilty of [TRANSLATION] “gross negligence in questioning the validity of what Forgues had said and failing to study carefully the engineering problem that had been brought to [his] attention”.
I therefore find that the contractor is also at fault and must share with the engineer the responsibility for the accident which is the basis of the claim for damages.
I cannot accept that the engineer’s fault is less serious than that of the contractor or contributed any less to the damage caused by the explosion of the caisson. The engineer had the ultimate responsibility for choosing the work method; he did not discharge his obligations in this regard. His fault is as great as that of the contractor; the liability should therefore be shared equally between them.
Accordingly I am of the opinion that the appeal should be dismissed, the cross-appeal allowed, the decision of the Court of Appeal varied so as to increase the amount of judgment to the sum of $700,000 with interest at 5 per cent from summons and an additional indemnity of 3 per cent per annum from January 1st, 1972, with costs throughout against appellants.
PIGEON J. (dissenting)—Appellants are the executors of the late Georges Demers, an engineer. They are appealing a decision of the Court of Appeal of Quebec, [1975] C.A. 653, which held him one-third liable for the physical damage caused by the explosion of a caisson which respondents (“the contractor”) were in the process of building for one of the piers of a bridge over the St. Lawrence River at Trois-Rivières. At trial Bélanger J., then a member of the Superior Court, dismissed the action in which the contractor was claiming the sum of $1,400,000 it had to spend to rebuild the caisson, a fact which is not contested. The Court of Appeal differed from the trial judge on the legal consequences of the written documents invoked and the facts found by him. Leave to appeal was granted on the condition that the appellants challenge only these legal consequences. Respondents cross-appeal.
It was the Corporation du pont de Trois-Rivières which, with the authorization of the Lieutenant-Governor in Council, retained the services of the engineer by a contract dated November 3, 1962. By this contract the engineer undertook to prepare the plans and specifications for and supervise the work on the bridge project. It contains, inter alia, the following provisions:
[TRANSLATION]
11. Construction methods and schedules, etc., of the contractors and subcontractors
The engineer shall examine the construction methods and schedules proposed by the contractors and subcon- tractors; he shall be responsible for verifying and approving their construction drawings and their shop drawings.
14. Information, advice and instructions
He shall make himself, or his engineers and technicians, available at all times to the corporation, the contractors and the subcontractors in order to provide them with the information, advice and instructions they need in carrying out the work.
22. Presence in Trois-Rivières and on the site
Throughout the duration of the construction work the engineer shall maintain an office in Trois-Rivières or within a radius of five (5) miles of the limits of that city; he himself or his representatives shall be present on the site in order to more effectively ensure that his obligations under this contract are fulfilled, especially with respect to supervision of the work and of the material and machine testing on the site.
A fixed-price contract for the construction of the piers was awarded to the contractor on February 25, 1965 by the Corporation du pont de Trois-Rivières with the authorization of the Lieutenant-Governor in Council and following a call for tenders. The plans and specifications prepared by the engineer, which form part of this contract, include for each pier a steel‑shelled caisson which also serves as a cofferdam. They do not contemplate the use of compressed air for sinking. On this point the specifications state as follows:
[TRANSLATION] In order to control sinking, prevent the caisson from slipping when descending through layers of soil with a very low resistance and keep the caisson sinking vertically to the exact location without deviation, the closing of some cylindrical wells by means of covers and the injection of compressed air into the wells shall be provided for by the contractor. Only the wells in the corners marked with the letter “D” on the drawings may be used for this purpose. It is expected that the pressure in each corner shall be distributed equally in the two wells used or that the difference in pressure shall allow for the weight distribution in the caisson. Any use of other wells to contain compressed air shall be permitted by the engineer only if the resistance of the framework has been found satisfactory for the new pressure conditions.
The specifications also contain the following clauses:
[TRANSLATION] The tenderers may, if they wish, submit an alternate proposal for constructing the cais- sons, together with drawings and a detailed description, but it is understood and agreed that they must submit a price for the project set out in the present specifications and shown on the plans in order for their tender to be considered. After the contract has been awarded, if the alternate project is worthy of consideration the contractor shall submit to the engineer for approval detailed plans with complete calculations for this alternate project.
…
The contractor shall submit in writing to the engineer the work method he intends to use and indicate where he proposes to construct the caisson parts that are to be built away from the bridge site. The engineer alone shall be free to accept or reject this method. The contractor alone shall be responsible for any delay or increase in cost that may result from the rejection or the adoption of a particular work method for carrying out any part or the whole of the project.
With its tender the contractor sent the Corporation du pont de Trois-Rivières a letter dated December 9, 1964, which reads in part as follows:
We are enclosing with our tender on the specified method for the above projects a separate tender using an alternate method of arriving at the same end result.
We are enclosing several drawings showing the various phases that the caissons would go through using our alternate method, as well as a schedule for this alternate and a drawing showing method of anchorage of caissons which would apply to either method. Further details of this scheme are readily available, should we be the successful tenderer.
…
Generally, we would use structural steel only in the bottom 13′ - 15′ of the caisson and in the cofferdams. The remainder of the caisson would be formed concrete. If even the limited amount of steel in the bottom of the caisson should appear to be difficult to get in time to maintain the schedule, we could provide a dry dock and build the caissons entirely out of reinforced concrete without additional charge to the Corporation. Also, all concrete, except the trémie concrete in the working chamber of the caissons, would be poured in the dry by standard methods. We would utilize false bottoms in the caisson cells for added floatation and to seal the work chamber to allow for excavation under compressed-air to a depth of approximately 88´ below water level. We feel that this type of excavation is a much more predictable method of sinking the caisson through the soft upper levels of the river bottom. After this stage the false bottoms would be replaced in part with domes on the top of the cells and excavation would then continue by the open caisson method using a clamshell.
The drawings enclosed in this letter are mere diagrams showing the various sinking phases under the alternate method; hardly anything but the elevations at the various stages planned are shown, without any construction detail. These stages include the use of a work chamber under compressed air. Above a diagram marked [TRANSLATION] “End of compressed-air method” one reads:
[TRANSLATION]
19. Erection of section XIII and put water in the three wells and 8′0″ of the excavation.
20. Erection of section XIV and remove the false bottoms.
The contract price was for the reduced amount which the tender submitted for the alternate method, the latter was therefore accepted.
The caisson in question was in the shape of a prism having a rectangular base 132 feet by 52 feet. In order to make it possible to excavate the river bed down to sufficiently solid soil, there were on the inside 24 cylindrical wells or cells 13 feet in diameter in three rows of eight. The bottom and the shell of the caisson were made of steel plate and the inside was filled with concrete around the cells, each being at the centre of a 16-foot square, and the walls behind the outside shell all around being approximately two feet thick. As indicated in its letter of December 9, the contractor had eliminated the steel plate cylinders which the engineer had specified for each cell from the bottom. It had instead used slipforms to pour mass concrete in successive layers inside the caisson in the shape required for the 24 cylindrical cells, to 56 feet in height. It was only then that it put in place, over the cells, steel cylinders approximately forty feet high for the purpose of completing the sinking of the caisson.
In order to excavate under compressed air under the caisson the cells obviously had to be sealed. Steel domes were therefore bolted under each of the 24 thirteen foot round holes, when the caisson was built. So that the excavation could be carried out in a compressed air work chamber the side walls projected 7 feet below the bottom, forming around the perimeter of the caisson what was called the cutting edge.
In order to make the transition from the compressed air excavation phase to the open excavation phase the domes had to be removed from the bottom of the cells. If the work chamber had been flooded it would have been necessary to have this work done under water. To avoid this difficulty the contractor decided to remove the domes before, rather than after, flooding the work chamber. For this it was necessary to equalize the air pressure on either side of the domes. This pressure was about 33 pounds per square inch, that is, over 300 tons per dome. The steel cylinders above the concrete therefore also had to be topped with domes in order to keep the compressed air inside each cell until after the last bottom dome had been removed. It was while these domes were gradually being removed that the caisson exploded on September 7, 1965: five bottom domes had been removed and one or two other cells were under pressure. Twelve workmen died in the disaster.
Regarding the cause of the accident, the trial judge flatly rejected defendant’s theory on the ground that it did not provide an adequate explanation. He found that the explosion of the caisson was caused in the manner explained by the contractor’s expert witnesses as to whom he wrote:
[TRANSLATION] The expert witnesses Hunziker, Newell and Lamarre are substantially in agreement in the conclusions they draw from their structural analysis of the caisson regarding its limited capacity to resist the internal stresses caused by the compressed air. In their opinion, in the engineering design calculations for the caisson consideration was not given to the upward pressure of the compressed air under the cell domes, to the pressure of the said compressed air on all the cell walls at 33.35 pounds per square inch or to its penetration into the joints between the different mass concrete pours, thereby adding uplift. Since the upper steel sections of the cells and their anchors were strong enough to resist the pressure, the upward thrust in a given cell went down as far as the bottom of the steel cylinders and transferred itself to the mass concrete in which the steel was anchored. This tractive force together with the uplift created in the concrete by the infiltration of compressed air created a cleavage plane at the point of least resistance.
The formal finding of the trial judge on this point is as follows:
[TRANSLATION] The Court is convinced that the cause of the accident is a structural defect or, in other words, the fact that the caisson was used for an operation it was not able to support. As designed, it could not be used for changing through cell pressurization from sinking by means of a pressurized work chamber to open air sinking.
Regarding liability, he first made the following observation:
[TRANSLATION] We are not concerned here with defendant’s liability toward the owner of the undertaking or toward third parties; the question must be decided by considering the legal relationships which may have existed between the contractor and the defendant. What the contractor is in fact claiming is the damage it suffered during the performance of its obligation to deliver the final product. It is the contractor itself which suffered the loss when the caisson exploded; it is not even a question of damages which the owner may have suffered and the contractor reimbursed. The contractor suffered the loss under its contract, and in rebuilding the caisson the contractor was fulfilling its own contractual obligation to deliver the caisson agreed upon.
Further on he said:
[TRANSLATION] The usual division of functions between the engineer and the contractor was in general provided for in the general and special specifications and in the contracts with the owner; however, this division applied only if the work was performed wholly in accordance with defendant’s plans and specifications. For the work in connection with the alternate method, a radical change in the responsibilities of each had been provided for: it was the contractor which in the case of the alternate method it had developed was to “submit to the engineer for approval detailed plans with complete calculations for this alternate project” …
It has not been proved to the Court’s satisfaction that detailed plans and complete engineering calculations were ever