BRIDGING THE MIKONUI RIVER

Hokitika Guardian, 3 October 1917, Page 2

BRIDGING THE MIKONUI RIVER

THE PROPOSALS

| Tho following was tlio offer from Messrs Stuart and Chapman representing the sawmijling enterprise at Ross, to the "Westland j County Council, read at Monday’s • meeting, in respect to adapting or converting the company’s proposed txam- : bridge over the Mikonui river into a bridge suitable to carry vehicle and ' stock traffic:— j “When previously going into tho matter with your Council, wo ( had not anticipated that tho acceptance of our offer would bo subject to your getting a special grant from tho Government to cover additional cost, in fact we were rather led to understand the only obstacle was that the Council had not pow or to expend public money on a privately owned Bridge, hence our last offer to sell tho completed bridge to you for £1,600. Although not stated in our letter it had been verbally stated to you by Mr. Chapman that terms could have been arranged for the above sum. “Wo think that had your Council looked into the matter from a business point of view they would not have attached much importance to the necessity of obtaining assistance from the Government. Tho annual payment of £123 7s. 3d. for twenty years would pay off the amount including interest at 6 per cent per annum.

“Wo could arrango to give some Kuril terms if such were necessary. We would point out that the rates of one rate payer alone, (Butler Bros. Ltd), for 16 years and four months would thus provide i -the Council with a traffic bridge over tho Mikonui, “In connection with design of bridge having 33 feet spans) not; meeting l with the Engineer-in-Chief’s Approval, we would prospectfullv point out that the Hokitika Bailway bridge has only 20ft spans over the main stream, and that tlie Mikonui bears no comparison with the Hokitika river in the matter of bring ing down drift timber. The Mikonui is notaby free ( fronr 'drifting timber of any dangerous size largely owing to tho fact that it has a rock-bound gorge immediately above the bridge site, and also owing to the fact that its banks below the gorge are not liable to erosion. “With respect to an objection pointed out by Mr. Dickson that a girder from the same source as ours had snapped in two through falling 2 or three feet, wo would like to joint out that the girder m question was a 16 x 16in. and was of a totally different rolling, imported at a different period, and possibly from a. different mill to out 19in. x Tins. It seems unreasonable to suppose that because some particular girder was in Grey-, mouth, under severe conditions, all other girders have thereby been proved to be unreliable.

THE PROPOSED STRUCTURE. The tramway bridge designed for the crossing of the Mikonui river by the sawmill company, consists of 14 twenty-feet spans, and twelve thirtythree feet spans, a total length of 676 feet. Two piles are proposed for each pier of the tramway bridge, but if converted into a road bridge, each pier would bo of three piles. The thirtythree feet spans would consist of two iron girders and two stringers, and tho twenty feet spans of four stringers. The width between the guard rails would he nine feet six, with tho tramnav iron rails in the centre over the two centre stringers. The handrailing would be canted outwards, giving a width of seven feet at the top. Piling, caps, corbels, stringers and wal ings to be of hardwood, the fencing nnd wheel guards to he of silver pine; and the decking and sheathing to be heart of rimu.

OVERSEER MILLNER’S REPORT. * ADOPTING TRAMWAY BRIDGE. I “I have the honor to submit the following approximate estimate of the * cost of the necessary addition to Messrs Butlor and Stuart’s proposed railwaw bridgo to allow vehicle traffic to use it in safety. ' I have provided tor one extra pile only in each pier, no proj vision is made for the cutwater pile, i which I presume will be included in ' tile railway bridge as it will not he safe | to construct piers with only two piles, j it would be impossible to lino them unless the cutwater pile is driven. The iron girders 33 feet in length and 19 inches in height upon which tho sleepers are to bo laid, prevent any diagonal wind bracing being provided for, to stiffen the outer hardwood stringers, the bracing is necessary, but cannot be placed in position owing to the depth of the girder which iB placed upon the cap, whereas the hardwood stringers will require placing upon corl>els, which will raise the bottoms of the stringers five inches above the bottoms of the girders. A correct estimate of the work is impossible until the site of the bridge and approaches is determined on and the correct levels given at each pier also length and height of each ap- j proach. Tho estimate /supplied here- j with provides for hardwood piles, two stringers in each span, corbels, capß, I waling and diagonal bracing. All decking pier lining and handrailing and standards are heart of rimu, the estimated quantity of timber for pier lining is low. On the whole the estimate may bo accepted to show that the addition to tho bridge will cost at least £1,043, exclusive of the cost of constructing the approaches.