ROAD MAKING.

Timaru Herald, Volume XC, Issue 13299, 30 May 1907, Page 6

ROAD MAKING.

ROAD METAL-HAND V. MACHINE

The Waimate County engineer yesterday reported to the County Council on the question of comparative cost of machinecracked and hand-broken road metal in thesa parts-, giving the result?; of inquiries made in adjoining counties using crushers where suitable materials are available. In the Levels County the cost of rock crushed to a 5-inch gauge varies between Is 3d and Is 9d per cubic yard, and in Waitaki County similar -work is performed for Is 3d. The varying character of the stone about Timaru explains the difference in the cost of the Levels work. Ill's crusher in •each instance is th.- Au~tin machine, capable of turning out between 50 and 60 cube yards of stone in 8 houis. 'ihe plants are used solelv for crushing quarried stone, and are not employed for gravel pit or river-bed . shingle, for which they are not suitable. Ihe rock spalls for crushing cost 2s 6d per cube yard in the Levels and 2s 3d to 2s 6d in Waitaki County. Hand - breaking of stone in this county is performed at much the* same, price'' as in those adjoining, the average rate being lOd per cubic yard. A large proportion of our local breaking, however, is done for Sd per yard, the average of lOd being the mean of the highest and lowest prices given by contractors for such work. If ihe jaws of the machine are set to a line gauge the stone is crushed to powder or so injured as to seriously affect its wear and durability. The stone is further flaky, which is' disadvantageous for compacting. The cost of these crushers is £360. The wear and tear is very considerable, and may be set down at not Its;; than £25 per annum, or 7 ]3er cent, of the first cost of the machine. It is found also that there is a want of uniformity in the size of the crusher work, and to obtain the best possible results the surface of the metal should be hand-broken after it is spread on the road. To make a stonecrushing plant pay ifc is necessaiy to give it nearly constant work, and have it so located as to reduce to the minimum the expense of handling both the unbroken and the broken stone. The materials available for the majority of the roads in this county are either pit gravel or riverbed shingle, the quarries being mostly' in the back countiy, where a comparatively small portion only of metalling would be done from them,- and a stone-cru&her plant would therefore, as past experience indicated, be out of employment most of iis time.

The prices quoted for hand-breaking stone {average lOd), Mr Bremner explain:-, refer to the cost of breaking big p.bblcs. among .shingle after being spread on road;-:, not to knapping quarried spalls. Mr Bremner also reported on tli3 cost of '*' scarifying" roads by plough and by scarifier. In the Borough of Timaru breaking up by plough cost per square yard, and by scarifier -|d per yard. The scarifier cost '£lßo, and must be attached to a traction engine. Some discussion took place on the reports. The engineer said he could not recommend the Council to acquire a scarifier. Mr Rhodes thought that scarifying would make new metal bind with the old much bitter, and prevent the grinding of the new. He would like to see an experiment made. The engineer thought that would not answer unless a good thick coat of metal was put on.

Mr Walker advocated a more liberal use of "blinding." One road shingled years ago had not "bound" yet. The engineer explained that was a ca.<-e of long haulage, when screened shingle was generally used to save haulage of waste. Some •screened shingle had been blinded with clay, and that had proved unsatisfactory. The difficulty was to get shingle with the proper amount of sand in it. The only way was to screen and then load up as much as was necessary. Mr Walker and the engineer had a discussion as to the best- -size of broken stone, the former preferring large, the latter small sizes.

On thti motion of Messrs J.yall and Rhodes it was resolved to authorise the engineer to try and borrow from the. Timaru Borough Council their road scarifier for a few davs.