NISHIMATSU CONSTRUCTION CO. LTD. v. R.

1996, NO. MA 1441

IN THE SUPREME COURT OF HONG KONG

APPELLATE JURISDICTION

MAGISTRACY APPEAL

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J U D G M E N T

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1. The Appellant was convicted on the 21st October 1996 of an offence contrary to Regulation 38A(b) of the Construction Sites (Safety) Regulations in that the Appellant "did fail to ensure that a place on the site which a person at any time worked so far as reasonably practicable, was made and kept safe for the person working there".

2. The prosecution was brought following an accident which took place on 1st September 1995. The accident occurred when retaining wall formwork collapsed during the pouring of the concrete for that retaining wall. At time of the accident a worker employed by the Appellant who was working inside the formwork died as a result of the failure of the formwork.

3. The formwork was constructed using timber boarding which was secured in place with steel tie bars. The steel tie bars were placed between the faces of the formwork and were to prevent the formwork moving outwards under the weight of the concrete as it was poured into the form.

4. The Appellant had caused a detailed design to be undertaken for this particular formwork so as to make sure that it would be safe. The designer gave evidence (PW-7) and gave as his evidence that he had designed this formwork using as the securing method threaded steel ties with washers, wing nuts and steel cones.

5. When the work reached the point of the construction of this formwork to build this retaining wall one of the employees of the Appellant decided to alter the authorised design by substituting for the threaded steel ties and their associated fixings a system of round bars with ties. It is common ground that the round bars have a lower tensile strength than the threaded bars and that the manner of fixing the round bars is more prone to loosen.

6. The workers used a greater number of the less strong ties fixing them closer together so as to compensate for the lesser tensile strength for each tie.

7. There was no evidence before the magistrate as to why the accident occurred. It seems to be likely that one or more of the form ties broke resulting in the formwork collapsing. This caused the working platform attached to the formwork to move which the magistrate found to be unsafe, and also led to the death of the worker working within the formwork. There is no explanation as to why the tie or ties may have broken, allowing the formwork to shift in this way.

8. The obligation under the Ordinance is to ensure the place of work "so far as reasonably practicable, was made and kept safe for the person working there". There is no doubt that the original design for the steel ties on the formwork was a safe method. It had been properly calculated with steel threaded bars of known minimum strength although it can be seen from test results in evidence that the strength of both round bars and threaded bars varied considerably but that all bar tested of both types had the required minimum strength. The design strength of the formwork using the threaded bars was in the order of 2.2 times using a standard rate of concrete pour at 2 metres per hour. The design strength of the formwork using the round bars was given by PW-7, who was accepted by the magistrate as an expert, as being in the order of 1.9 under the same conditions as the use of the threaded bars.

9. It is accepted by all parties that the substitution of the round bars for the threaded bars was unauthorised and had not been the result of proper design and analysis. It is accepted that the cause of the collapse is not known. It was accepted that if the use of the round bars was not safe then the appellant was guilty of the offence and that the onus was on the appellant to show the substitution of round bars for the threaded bars was safe. The decision for the magistrate was whether the formwork actually in place at the time of the accident was "so far as is reasonably practicable ..made and kept safe for the person working there." The decision was not whether a safer system existed or even whether a system less safe had without authority been substituted for a safer system but whether at the time alleged the "place on the site" was"as far as reasonably practicable" "made and kept safe for the person working there."

10. As to whether the system in place was safe as required by the regulation did require analysis of the strength of the original system as well as that of the substitute system but the issue was not whether one was safer than the other. Nor was the fact that an accident occurred necessarily proof that the system was unsafe. It is clear from the findings of the magistrate that other factors could have contributed to the accident other than the type of ties on the formwork. For example the safety factor of 2.2 for the threaded rods depended on a pour rate of 2 metres per hour. The expert accepted by the magistrate testified that as the concrete at the bottom set it helped support the concrete poured in above it. Thus if a pour rate of more than 2 metres per hour were used the safety margin in respect of both systems would drop as it would if the concrete at the bottom of the formwork failed to set when anticipated and the pour continued. I do not speculate as to the cause of the accident merely illustrate the proposition that an unsafe workplace cannot necessarily be inferred from the fact that an accident occurred.

11. The magistrate accepted from PW-1 that the use of the round bars by PW-4 and the manner in which he used them "should be safe according to my calculations." PW-7 said and it was accepted by the magistrate that he calculated the safety factor of the round bars at a pour rate of 1.8 metres per hour to be 1.8 times " and the round bar (formties) shouln't break. It is quite safe to use the round bar formties." And further :

"If the pouring rate is 1.5 metres per hour using the said spacing and dimensions as described the safety factor of the round bar formties is 1.9 times and the round bar formties shouldn't break. It is quite safe to use the (round) bar (formties) in that manner under normal conditions."

12. He went on to say that the weather, the water content of the concrete, and the workmanship of the workers were factors which he considered might make the conditions other than normal. Having referred to those other than normal conditions he qualified that evidence by saying :

That is why I use a figure larger than 2 times but those figures 1.8 times and 1.9 time are so close to 2 times so I can only say they are quite safe."

13. These words were a clear qualification of his evidence that the round bars were safe under normal conditions. The magistrate interpreted this evidence as meaning that the system was not safe except under normal conditions he finds:

"It is quite clear that P.W.7 was of the opinion that it was quite safe to use the round bar formties on that formwork in the manner used by P.W.4 only under normal conditions but he was uncertain whether it was safe if abnormal conditions prevailed."

14. That was a misconception of the evidence of the witness taken as a whole. His evidence was that it was quite safe to use the round bar system under normal conditions and that taking into consideration unexpected factors his designs used a safety factor of more than 2 times but that the figures of 1.8 and 1.9 times are so close to 2 times that he could say they were quite safe.

15. The view of the evidence taken by the magistrate led him into further error in the test he used to determine whether the place of work was safe. He finds:

The accident occurred because P.W.4 caused round bar formties to be substituted for the approved threaded formtie system regarding the construction of the formwork of Section E1 in such a manner that some of the round bar formties broke under the pressure of the concrete poured into the formwork. Before the accident occurred it was reasonably foreseeable that an accident of this kind might happen.

The prosecution has proven that in spite of the fact that it was common practice to use round bar formties to build formwork there is another method to build formwork using threaded formties which would be safer than the method of building the formwork of Section E1 using round bar formties and that other method would not necessarily be unreasonably difficult and impracticable."

16. It is apparent that the magistrate has adopted the test of whether there was a safer system than that in use at the time of the accident rather than whether the system in use at the time of the accident was "so far as reasonably practicable".. "made and kept safe for the person working there." Since the wrong test has been applied the appeal against conviction is allowed.