DESTRUCTION OF A RAILWAY BRIDGE.

Oamaru Mail, Volume I, Issue 98, 14 August 1876, Page 2

DESTRUCTION OF A RAILWAY BRIDGE.

The " Grey River Argus " gives the following particulars of the collapse of the suspension bridge on the Greymouth and Brunnerton line on the 29th ult. :—" The bridge was all but completed, in fact it .only required the flooring and rails to be laid. Everything about it appeared to be in perfect order. The superintendent of the work, Mr. R. J. Johnson, had succeeded in securing a perfectly even tension on the wires ; the heavy timber lattice work had been well and truly put together, and, to all appearances, and according to the design of the engineer, the bridge bade fair to last for half a century or more. And yet at four o'clock yesterday morning the anchor plates on the south side of the bridge snapped, causing, of course, all the suspension wires connected with them to carry away, and the whole structure collapsed and fell into the river. When first the noise was heard, some of the residents at Brunnerton thought that the Brunner Mine had caved in, some thought that a great landslip had taken place, but none thought for a moment that the bridge had given way. The destruction is complete, except that the wire can be recovered, but all the wood work, constructed as it was of the best black birch, is knocked into matchwood. Great beams are torn asunder, iron bolts and braces doubled up, and nothing has escaped except the piers at each end, which have sustained 110 damage, excejrt that the saddle plates, over which the wires passed, have tumbled off, but they can be easily replaced. As already stated, the cause of this catastrophe was the breaking of the anchor plates on the south side. To make the occurrence intelligible to our readers, we may explain that the cable, or collection of wires from which the roadway of the bridge was suspended, were attached to a block of cast iron imbedded in the rock, and placed in such a position that unless the iron gave way the suspending wires must remain firm. These iron plates were 4ft. 3in. long, 4in. in thickness, and 12in. wide, and had in the centre a raised rib or backbone, as one may say, sin. by 3in., along the length of the plate. In tins plate there were thirteen holes, through each of which an iron rod was placed, having a nut screwed at the back of the plate, and a hook in front, to which a portion of the wires was affixed. The whole strain, of course, was upon this iron plate, which was of cast iron, and it proved too much for one of them, which broke off nearly in the middle, and the extra and sudden shock to the other one produced the same disaster. The plates were cast at the Greymouth Foundry, but it is fair to say that the fracture in each case shows that the castings were good and of good metal, and, as yet, Ave do not think that any blame will be placed upon them. The accident appears to have arisen from a miscalculation as to the strain which the anchor plates were capable of sustaining. And it may be said that they should have been of forged, instead of cast, iron—anyway, a great mistake has been made, and the only gleam of comfort there is about the whole business is, that the accident happened when it did. Had it occurred in the daytime, when about twenty men would have been at work upon the bridge, and perhaps a number of pedestrians, a fearful loss of human life would have been inevitable. Thank Heaven no life has been lost, but the disaster is, in every sense, a serious one. We may estimate that at least five thousrnd pounds worth of work has been destroyed, and that many months must elapse before the bridge can be re-erected. This means a very serious check to the coal trade, which, but a day ago, appeared to be on the eve of vigorous development.