James Walker's evidence to the Coroner's Jury
Suffolk Chronicle 24 May 1845 p.4.
James Walker, Esq., being sworn, said was a civil engineer; that he was a member of the Institution Civil Engineers, and had been president thereof for the last ten years. At the request of the Secretary ot Slate for the Home Department, he had come to examine the cause ot the failure the suspension budge. To acquaint the Jury with the nature of the communications he had received, he handed two letters the Coroner, who sent them. Mr. Walker deemed it fit, before the reading the second letter, to state, that had written to the Home Other, stating his readiness to undertake the duty, and was ready to do so and come immediately, because he had given up all attendance on railway business.
Mr. Walker then proceeded to detail the early history of the bridge, which we have before presented to our readers, and from which it differed in no matter of the least importance. The bridge been designed by Mr. Scoles, the architect, thee drawings were given to Mr. Green, a surveyor, at Yarmouth, at the time well known in the district. It appeared that the work was offered for competition, and the late Mr. Godfrey Goddard was the contractor for execution of the bridge. There were altogether four suspending bars two on each side forming the chain; the bars were connected by bolts passing through the openings, or eyes, formed in the ends. These bars were two inches and a half wide, by seven-eighths of an inch thick. From them, rods of an inch square were suspended, to carry a roadway which was 11 feet nine inches, and divided by an iron grab into the carriageway, g foot 9 inches, and a footway each side, 4 feet in width. The span or length of the bridge between the towers was 92 feet. The deflection of the chains, 7 feet 4 inches. In 1842 the Yarmouth and Norwich Railway Act was passed, which obtained, as he understood, after much litigation, by which the bridge was constituted the only communication between the railway and the town. Mr. Cory continuing to receive the tolls and promised to widen the bridge. It appeared that on this occasion Mr. Scoles had been consulted, and recommended the carriageway being widened sufficiently for two carriages; the footway was being framed on each side upon planks, supported iron branches. The foundation appeared have been well built and the piers stood well.
It was stated to him that the crowd collected on the 2nd of May was on the south side of the bridge. and had consisted chiefly of children in the front rank, with adults behind, to see some exhibition that day on the water. They were supposed to be four or five in depth and they had been calculated at from 300 too 500. He had heard from the Coroner that had seen double the number,or more, on the bridge; - but then they had been spread over both sides so that the two chains were equally loaded. It had also been stated by a witness that a smart crack was heard, which led him look up. when he saw that one the bars had been broken, the two parts fairly separated, and that five minutes afterwards the fatal event took place. The cracking was, no doubt, occasioned by the snapping of the bar which first gave way. There being then only one of that pair of bars left to support the whole weight; this bar also gave way. when the platform, being entirely unsupported, fell into the water. The fracture in the bar that first gave way was about 8 inches from the upper end; and the other, about the same distance from the lower end of the bar. (To illustrate what he meant, he produced a model.) It appeared that in forming the bars, the circular end had been first made by themselves, and then a straight bar of the proper length introduced in each of the pieces, having what was called a SCARF. There was difficulty in getting work of kind perfectly connected, and it was at these points that both the bars in the present case broke. On minutely examining the bar that first failed, it was evident for some length of time, or perhaps from the original forming of it, the weld was imperfect; not more than one-third of the meeting surface being united, the other two-thirds shewing a rusty surface. The weld in the other link was good; but on looking at the bar, he found it an inch longer, which was no doubt, caused by it stretching before it broke. He had had the quality of the iron tested in a variety of ways and found the straight part or middle of the bar to be much better than the two ends. Mr. W. then produced several specimens describing the manner in which had experimented upon them. As far as he could judge the pieces produced, the straight bars, were good iron. The quality of the ends was not according to the specifications, nor were they in his opinion proper for the purpose. Had any efficient means testing been applied, the inferiority of this part the iron must hare been detected. Mr. W. then produced a specimen of the part which he had alluded. The description of iron specified was so true it could hardly had. He would now make a few remarks on the sustaining power the bridge compared with the load upon that day. Taking the load at that time to all the south chain, he found calculation that the two rods being two and half inch by seven-eighths of inch each, were capable of supporting a temporary load of 56 tons without injury of course presuming the material to be estimated for. He found the strain upon the chains, taking 400 people at seven stones weight each, with a due proportion of the weight the bridge - because the chains would have to carry their own weight and that of the platform in addition to the load - taking them altogether the strain at the time of the accident seems have been about 44 tons, therefore, but for the defect in the quality the iron and of the workmanship, the strength exceeded the load. He did not consider that there was excess enough in the bridge, because a legal allowance ought to be made for imperfections. If they supposed one the bars to be bad, as was unfortunately the case here, they would then have the strength less than the strain. The bridge appeared to him to have been not too strong as originally formed, and the addition made to its width for two carriages to pass, and two footways, as had been in the present case, proved injurious.
In reference to the sufficiency of the bridge to carry the greatest weight that could be put upon it, be found its strength a little above the weight, but not sufficient to be practically efficient; but it was not proper to say that the occasion of a close mass of people packed upon the bridge could scarcely occur, though it ought to be provided for. Mr. W. intimated the probability that the weight which had on former occasions been accumulated on the bridge, had injured it, and might have accelerated the fatal accident.
From the remarks which he had made he was led now to present them with the conclusions at which he arrived, which he delivered as follows: -
"1st. I consider the immediate cause of the accident to have been a defect in the join or welding of the bar that first gave way.
"2nd. That the quality of the iron and workmanship, so far as I have been able to examine, were defective, and would not have been permitted if the work had been properly examined at the time of using.
"3rd. The widening seems to have been made without sufficient reference to the original strength of the bridge and the weight it had to support, and aggravated the evil.
"4th. In the original construction of the bridge the contingency of a great load being laid on one side does not appear to have been contemplated. If it had I think the links on that side would have consisted of more than two bars, any one of which was unequal to the load the bridge was likely to carry."
He had only to add that in the investigation he had received every possible assistance from Mr. Cory, who had produced all the documents in his possession. They had enabled him to come to his conclusions in less time than he would otherwise have been able to have done. He might add that the whole of the weight of the bridge had been taken with the great accuracy, and the addition made to the width, as far as its own weight went, was comparatively small, and important with regard to mass, including the suspending chains. Before, the addition was made the weight was 17 tons 14cwt. 1qrs. 25lbs.; with the additional weight the whole was 20 tons 8cwt. 0qrs. 9lbs., so that the addition was only 2 tons 13 cwt.