ROADING THE PLAINS.

Hauraki Plains Gazette, Volume XXXIV, Issue 4514, 12 January 1923, Page 1

ROADING THE PLAINS.

AN EXPERT’S REPORT. ESTIMATED COST. At the request of the Turua Town Boad the following report was prepared and read by Mr C. Skitrpp, C.E., representative of the Union Asphalt Co., at a public meeting of ratepayers at Turua on Wednesday evening last: “As requested I herewith submit my report upon the question of laying down bituminous roads in your district, but before going into the matter pf the methods employed, the materials used, and the approximate cost of the proposed work I will say a few words about .the material know as bituminous asphalt, of which there are two distinct classes, the natural asphalt obtained from bituminous lakes, including Trinidad,, which produces what is known as Trinidad asphalt. The other bituminous asphalt i& what is known as residual asphalt, and is obtained by distillation. After all the valuable oils and spirits have been extracted from the crude oile obtained from the Californian oil wells the residue is refined to so high a degree that 99.7 per cent, of pure bitumen is obtained. This is what i& known as Union asphalt, and is the purest bituminous asphalt on the market, being absolutely free from paraffin. Paraffin is a waxy .material with no cementing or adhersive properties ; hence its presence in a paving material is a serious source of weakness. The use pf the word bituminous in regard to paving material is very misleading, as there are .several classes of bitumen on the market quite suitable for the work for, which they are intended, but ,are unsuitable for road construction. I have come across two instances lately in which local bodies quite innocently ordered bitumen, and upon its arrival found it unsuitable for road' work. Quite a large number of people are under the impression that union asphalt is a superior tar preparation. This, is a pardonable error, as both materials are black and liquid w.hen being laid, but in composition tjiey differ greatly, union asphalt being purely a mineral product, free from vegetable oils, which evaporate when exposed to the atmosphere. Even Taranaki local body members who are now using union asphalt on their roads often refer to them as tan-sealed roads. This is, of course, misleading to other local bodies who intend laying down modern roads with the best materials available, which is cetraialy not tar or any of its preparations. I do not wish to imply that Lar will not make good roads, for the Taranaki roads have proved beyond a doubt that tarsealed roads are less costly in maintenance than are ordinary waterbound macadam roads, but the experience of the past ten years has prove ! to most of the Taranaki engineers that the maintenance on union asphalt roads is about one-third of the tarred roads.

“I shall now deal with my own experiments, and those of various atliei engineers who have been doing experimental work for .the past ten years in the hope of improving the roads under their supervision. I shall first, deal with the experiments of Mr Alf. Hansen, engineer to the Waimate West County, and late of Eltham Borough. He is one pf the oldest pioneers in tar road construction, and is, I believe, one of tlhe best authorities on tarred roads in the Dominion, and his tarred roads in Waimate West are certainly a credit to him, but owing to the comparatively heavy maintenance cost on these roads he last year sprayed a portion of tarred road (near Hahaia) with union asphalt, and he is so satisfied wtih the result that he is continuing the same class of work this year. Mr Fitzgerald, engineer to the Eltlham County, also carried but some experiments in surface sealing tarred roads with union asphalt in order to reduce the maintenance cost, and his council has now ordered 22400' gallons of union asphalt to carry bn the work this season. Mr Sturrock, engineer to the Hawera Borough, who is one of our foremost engineers and an old pioneer in tarred roads, is confident that the lasting quality of union asphalt is three times that of tar, and he has order a large quantity of union asphalt for the purpose of surface sealing tarred streets, this year. Mr Merrideth, engineer to the Taranaki County, is this year layingdown 40,000 gallons of union asphalt on bis roads, having altogether abandoned the use of tar. Mr CorkilJ, the chairman of the Inglewood County, last year laid down fifty chains of union asphalt roadway, and is continuing the same class of work this year, having also abandoned the use of ,tar. Mr Forbes, the foreman of Stratford Borough, is this year surface scaling his tarred street with union asphalt. Mr Spence, engineer to the Stratford County, is also doing some experimental work in surface sealing with union asphalt. Mr King, engineer to Che Patea County, has also carried out several experiments, with the result that he is this year laying a considerable quantity of union asphalt on his county roads. “All these cases go to prove .that the Taranaki engineers' are moving along with the times, benefiting by their own experiments and making use of the material which in their opinion gives the best results, “I shall now deal with my own experiments, which cover a period of nearly ton years. In 1913, when engineer to the New Plymouth Borough Council, I laid down two portions of Brougham Street for experimental purposes. One portion was laid down with union asphale, the other portioii with tarred macadam. Both portions

were laid under the penetration system, and both carried ithe.same class of traffic. The asphalted portion received no attention in the way of maintenance for nine years, at the end of which period ft was still in good order. The tarred portion was surface sealed every two years, and at the end of nine years was in a worse condition than .the asphalted portion. In 1915 I laid down union asphalt on the main road passing through Ellerslie. The maintenance to date has been nil, and the street is still in good order, while a portion of tarred road laid in 1919 is absolutely worn out. Both portions carry the same class of traffic. In 1916 I laid down Victoria Street, Cambridge, in union asphalt, and up to date there has been no expenditure for maintenance. This case is rather interesting from a maintenance point of view. The street, which is a wide one, had previously been laid down in tarred macadam and was costing £4OO per annum for maintenance. The cost laying it in union asphalt was £l2OO, which represents the money expended on the tarred road in three years ; as it is six years since it was laid and it cost nothing for amintenance in that time the borough council is £l2OO in pocket and has a good road in place of a bad one. In 1916 I also laid dowi High Street, Dannevirke, in union asphalt. The maintenance to da,te has been nil. Other roads and streets upon which I laid union asphalt in 1916 and upon which there has, been no expenditure since, are Te Awamutu rain road from railway gate towards the town, Takapuna Lake Road, and Waiuku main street. “The Tamaki West Road Board, after watching the Ellerslie Town Board’s experiments for the past seven years, has just let a contract for five miles of union asphalt roads. The Taranaki County, after laying tarred roads for ,a period of ten years, has this year ordered 105,800 gallons of union asphalt, chiefly for the purpose of surface sealing tarred roads. These facts, which can easily be proved, should cause local bodies to make inquiries before going into large loan proposals which may land them into heavy maintenance costs. “I have been over the roads, which you propose including in your reading scheme and consider, that the penetration method would suit your case, being cheap and efficient. This method consists of scarifying the surface of .your present metal, forming to an even camber and covering witn new metal, which is then rolled until the surface is solid and free from inequalities.

“The union asphalt is then heated to a temperature of 350 degrees F. and sprayed into the. surface of the road' under pressure, using one gallon to the square yard. “The surface of the road is then covered evenly with metal ships at the rate of one cubic yard to fifty square yards of road surface, and .then rolled in. “The traffic is then allowed free use of the road for. a period of three to six months, when the surface of the road is swept, clean and surface sealed with a light dressing of union

i asphalt and coarse sand. If your j roads arc done in this manner there ’ should be no maintenance cost for six to ten years, according to the amount of traffic placed upon .them. The interest paid upon your reading loan will not greatly exceed maintenance cost on your present water bound macadam roads. The experience of the Eltham County in regard to the Eltham-Opunake road will make the.point cle.ar to you. Before the road was .tar-sealed the maintenance cost was £3OO per mile per annum. By surface sealing with tar this was reduced to £l'so per mile per annum. By surface sealing with union asphalt this maintenance will be further reduced to at least £75 per mile per annum. “On estimating the cost of you” I proposed road work I shall deal with each road separately, as .they require slightly different treatment in the way of formation. The estimated costs ; are as follows : I Hauraki Road, —From Willow Drain ! to post office, 80 chains long by 12 feet wide: Scarifying and forming, 80 ’chains at 50s, £2OO ; metal 4in thick, 782yds as 20s, £782; metal chips, two dressings, 250yds at 20s, £250; union asphalt, t'wo dressings, 44 tons at £lO 10s, £462 ; rolling, 80 chains at 255, £lOO ; labour, spraying, including horse hire, £BB ; firewood, £22 ; foreman of works, supervision, £35. Total, £1939. Hauraki Road.—Post office tp north' boundary, 52 chains by 10 feet.: Scari- ' fying and forming 52 chains at 40s, £lO4 ; metal 4in thick, 4'23yds at 20s, £423; metal chips, two dressings,

124yds at 20s, £124 ; union asphalt, two dressings, 24 tons at £lO 10s, £252 ; rolling 52 chains at 255, £65 ; labour, including horse hire for spraying, £4B ; firewood, £l2 ; foreman of works, supervision, £25. Total, £1053. Raratuna Street.—Hauraki Road to Oparia Road, 27 chains by 9 feet: Scarifying and forming 27 chains at 20s, £27 ; metal 3in thick, 149 cubic yards at 20s, £149 ; metal chips, two dressings at 20s, 60 cubic yards at 20s, £6O; union asphalt, two dressings, 12 tons at £lO 10s, £126; rolling 27 chains at 20s, £27 ; labour, spraying, including horse ihire, £24 ; firewood, £6 ; foreman of works, supervision, £lO. Total, £429. Oparia Road—Giber’s to Johnston’s, 18 chains by 9 feat: Scarifying 18 chains at 20s, £lB ; metal 3in thick, 100yds at 20s, £100; metal chips, two dressings, 40 chains at 20’s, £4O; union asphalt, twp dressings, 8 tons at £lO 10s, £B5; rolling 18 chains at 20s, £lB ; labour, spraying, including horse hire, £l6; firewoo-i, £4; foreman of works, supervision, £7 10s. Total, £285 10s. Piakb Road. —Post office to Hicks’ corner, 67 chains by 12 feet: Scarifying and forming 67 chains at 30s, £lOO 10s ; metal 6in thick, 983 cubic yards at 20s, £983 ; metal chips, two dressings, 197 cubic yards at 20s, £197 ; union asphalt, two dressings, 37 tons at £lO 10s,. £3BB 10s ; rolling 67 chains at 20s, £67 ; labour, spraying. including horse hire, £74 ; firewood. £lB 10s ; foreman of works, supervision, £35. Total, £1863 10s. Grand total, £5570.