MAKING ROADS.

Taranaki Daily News, 3 November 1915, Page 6

MAKING ROADS.

THE VALUE OF TAR TREATMENT. COUNTY ENGINEER'S REPORT. An interesting report on tar treatment of roads was presented to the Taranaki County Council yesterday by the county engineer (Mr. R. W. Fisher). The report stated:~'Tn company with your chairman I visited the Eltham, Hawera and Waimate West counties on October 22 for the purpose of inspecting the result of tar treatment on the various roads. At Eltham we were met by Mr. Basham, county engineer, who accompanied us to the central depot, where the material is prepared and the method explained. In this county Tlestar' has I been most extensively used with good results. Two methods of application have been resorted to. One method adopted is pouring the 'Restar' on the surface of the road after first carefully sweeping the road to remove all dust, and afterwards pouring the "Restar'' on after heating to a certain temperature. The road then receives a coat of shingle. The second method is to scarify the road, and after adding a light coating of new metal lightly roll the road with a steam roller and apply the "Restar" by pouring it on hot until the preparation has run into the interstices of the metal. This in turn receives a further light rolling, after which a top-dressing of hot tar is applied, followed by a light coating of shingle, and the road is then ready for traffic. The latter method, although more expensive in primary cost, gives the best results, and is the one that is being generally adopted for the roads in that county. Mr. Basham took us over the Hunter road, which was laid about four years since in accordance with the last method described, but in this case tar from the gasworks, dehydrated to eliminate the light oils and ammoniacal liquor, which exist in all crude tars, was applied. The road, in spite of no expenditure in maintenance for the past four years, showed a surface equal to and better in many cases than the more expensive proprietary bituminous mixtures. "The Hawera-Countv Council have not as yet adopted tarring to any great extent. The Council, however, have on order a nlant which will cost them £I2OO, and which is expected to arrive from England in the course of a month or two. The county engineer (Mr. Moggridge) gave us all the information in his power, and explained the methods he had adopted. 'Soltar 1 has been used on portions of these roads, and inspection does not show any material difference between that preparation and 'Restar,' but I understand that the quality of the various consignments of 'Soltar' vary, and some are not good. The ordinary gas-tar dehydrated is to be adopted generally in this county. "At Manaia we were met by Mr, MePhillips, chairman of the Waimate West County Council. This county is just embarking on an extensive scheme of tarred roads. A length of the main road between Manaia and Hawera has been put down with ordinary gas tar obtained from the Wellington gsworks. and has worn out very badly on the sides. This is attributed to an 'error of judgment' in preparing the tar. and this contention is supported by the fact that a portion of the road which has been laid with tar from precisely the same consignment as that used in the defective length has made an excellent job, eoual to any we were shown. The method adopted here is that of tar-sealing. The question of cost is difficult to arrive at in any of the three counties visited, as it differed considerably in each district, and this is only natural, as cost is affected by local conditions, such as distance of carting material, etc., and it is only by means of a practical trial that this can be ascertained.

"I am glad to have had the opportunity of making this inspection, as it confirms my opinion, based on personal experience, that equally good results can be obtained by using tar from the gasworks. I might mention that in 1908 I superintended the construction of a road in one of the principal thoroughfares in the city of Bombay. India, which was laid with distilled tar from the gasworks. The street in question carirefl traffic in 24 hours equal to the South road in a month, the nature of the traffic being exceedingly heavy, and consisting to a great extent of bullock waggons conveying heavy bales of cotton from the Bombay cotton mills, and it is gratifying to learn from a member of the staff of the Daily News, who has recently returned from that city, that during eighteen months he travelled this street daily, and never remembered any money being spent in maintenance. I recommend that the portions of the roads to be treated shall be first scarified, and where necessary new metal added, to the extent of, say, 9 cubic yards per chain, and after this has been rolled lightly boiling tar, properly prepared, to be procured from the gasworks, poured in. This should be rolled to consolidate it, and a top-dressing of tar applied and lightly swept over with ordinary brooms, I after which it should receive a coating of fine shingle, which in its turn should receive a light rolling. I advocate this method of pouring the tar into the unblinded metal as against tar-spraying in that by adopting this principle the material will be bound in at the edges, whereas in the spraying method the edges are the first to give out, as it is here that the greatest wear takes place, and in most of the roads where tarsealing has been resorted to my contention is exemplified. "As an approximate estimate, I give B'/od per square yard, equivalent to. say, £3 18s per chain, or £312 per mile. I wish to point out to you that unless the road surface is properly prepared to receive the tar by scarifying and bringing it to au even surface, the inequalities which exist in the ordinary metal roads are not minimised, and the jolts and pools of standing water will still make their presence felt. As regards maintenance T would point out that whatever system of tar treatment is adopted there is the annual maintenance charge to be faced, which in the case of ordinary tar I estimate at £1 per chain. As regards this county, there is a considerable mileage of roads which I consider should be wider metalled before it is ready for treatment. In conclusion, we have to thank Mr. Basham (county engineer, El.tham), Mr. Moggridge (county engineer, Hawera), Mr, MePhillips (county chairman, Manaia), and Mr. Lopdell (county engineer, Stratford,*, formerly of Waimate West) for the courtesy extended to us.''

The Council adopted the report, and decided to lay down a length of road at Omata Hill, in ordinary tar, from the gasworks, as recommended by the engineer,