ROADING QUESTION.

Taranaki Daily News, Volume LVII, Issue 263, 16 April 1915, Page 4

ROADING QUESTION.

REPORT ON TREATING ROAD SUBFACES WITH TAB PREPARATIONS. The following interesting report was submitted to the last meeting of th* Patea County Council by its engineer:—) The main roads may be divided " 3 two classes, that which tarries mainly outsido traffic, consisting of motor vehicles for the most part, and travelling stock, and the portion which carries local traffic such as milk waggons, carts, traps, etc., in addition. In this report, figures and estimates given only apply to the latter portion (that carrying the heaviest traltic) which comprises the greater portion of the roads. ORDINARY WATER-BOL'XD .MACADAM,

At tlie present time re-metalling costs us, allowing 10 cubic yards of metd und screenings to the chain, ab»uf£ll per chain, or 2a 3d per square yard. The life of this inetal, under present traffic conditions, would he about eight years. The cost of maintenance during that time would ho about £4 Is, mad* up as follows: Ordinary surface work, such as raking up stones, backing up inetal and patching, 21s; claying one* annually, 325; scarifying, raking into shape and rolling once during the'period, including 1V» cubic yards of inetal per chain added to weak places, 235. This works out at a total cost of £l4 Is for the period of eight years, wlie% the road would require re-metalling. TREATING SURFACES WITH TA* 'I'RKI'AUATION AND SHINGLE. ' Tlie road must first bo re-metalleit and thoroughly rolled, and afterward# allowed to be further consolidated. by trallic for a short time. The cost oi this would he about £9 per chain, : as less metal would bo required, nothing having to be allowed for wear, thr metal simply acting as a foundation. Three months after the first coat a second coat should he applied. This should then last foT two years, when another coat would be required, and so on. If the fresh coat is applied every two years the road should stand without any wear on the metal. The cost of the work would be as follows, covering a period of eight years: Re-metalling,.€ 9; first coat, .C 3-, four additional coats, £Bf ordinary Maintenance (say), £1 10s; interest on extra plant required, Is; total cost for period of eight years, £2l lis.

SUE FACING THE ROAD WITH TABI RED CHIPS, GENERALLY KNOWN .AS GLADWKLL SYSTEM. The best example of this work I havi seen in New Zealand is in the borough of Palmcrston~ North. Tho method adopted there is ns follows: —The road is first re-metalled an for tar surfacing, great care being exercised to obtain an even surface with correct camber. The surface is then very lightly scarified, and tarred chips, sullicient to give a consolidated thickness of au inch added. Ttle surface is then rolled with a light hand roller, and allowed to stand for two or three dais, the traffic being kept oil'. It is then well rolled with a steam roller. :\vd opened for tr.vllic _ After the lapse of a few week.", a coat, of tar and snnd is applied. In preparing the tarred metal chips, the chips, which range up to about half an inch in size, am first ho;ited, and then mixed >vir.lt bciilimr inr. They are then allowed to mature for fvo-n. six to twelve months before being put on the road. The engineer informed me that ha found the maintenance only about 25 per cent, of what it was for ordinary water-bound macadam, and that it would last if well maintained for a very long period. In Pnlmerston this work costs about Is 1(M per square yard, not including cost of preparing the road. With the extra price for metal chips, tar and carting, locally the work would probably cost about 2s fid per square yard.

COMPARISON OF THE DIFFERENT SYSTEMS OVER A PERIOD OF NIXE YEARS.

I am taking o. period of nine years, because at the end of that time, for the expenditure shown, the two former systems would leave the. road in about the same condition.

AVnt er linnnd Macadam—Re-metalling twice and maintenance, £24 ss.

Treating surface with tar preparation —Re-metalling once and cost of treatment over period of nine years £2l. Glad well System - -Re-metalling, treating surface with tarred chips, and maintaining for nine years, £25. In regard to this latter system, i' e road would he in a better condition at the end of this than in either of the two former systems, as some of tarred chips would remain. Tn drawing up this report T have Tathor under-estimated the cost of our present system. Should our present method of metalling prove to last over eight years the comparison still applies, 'as the*traffic being lighter than estimated. the maintenance of the other sys j tenia would be likewise reduced.