MODERN ROADMAKING.

New Zealand Herald, Volume LVI, Issue 17295, 20 October 1919, Page 4

MODERN ROADMAKING.

Sir, —I ehouLd like to draw attention to ths sound sense of the letter of 14th inst., from "Road Engineer." We are, or we hope we are, on the eve of the putting down of an extended srstem of fir? - class roads throughout the Auckland province. A highway of especial interest and significance is that from here to Kaitaia and Waipapakatrri. Now tho Kauri Gum Industries Amendment Act of 1912 was passed (on the initiative of the present Commissioner of Crown Land? Northland, Mr. E. F. Grevilie), to enab'e the leasing of gum lands for taking out gnm " and other valuable products." The excellence of the legislation consisted in provisions for working the land to the best advantage, instead of the current system of pot-holing, and* of leaving the. land levelled with a soil surface. But thf> T>oinfc of the matter and its relation to our roads lies in the words in quotation maris, viz.. "other valuable product-?." This gum soil contains a. high percentage of tar. This tar again has. of its" verv nature, a high content of the essential oils of kauri gnm, the valuable properties of which are well known. vVe come, therefore, to a source of supply for roadmaking, and of a product which should receive the serious attention of road en-' gineers. Whatever may be the merits of tar versus concrete, as referred to in correspondence. the tar spoken of is coal-tar, and it is highly probable that kauri peat tar will be immensely superior to it in every respect—durability, resiliency, and, an important matter at all times, cheapness. I trust that this *ar will be produced in great quantitv from the peat swamps that lie between Ranganu Bay and Houhora, and in time ba j)nt down upon the Kaitaia arterial road after recognition of its merits. These swamps are Crown lands, and a great development will take place thereon during the coming summer. As Mr. Massey said in Parliament, these northern lands are "on the eve of a term of prosperity such as has never been experienced." J. Masjohibank; STEELE.

Sir,— I think "Road Engineer" is-'-no doubt unintentionally not quite accurate when he state* in the concluding paragraph of his letter that an English company threw out the longitudinal sleeper owing to its lack of resiliency, if, as jl presume, he refers to the GreatWestern Railway Company, which from Brunei's time up to the time of the conversion of the old 7ft guage to the standard 4ft B£in gauge, used the Barlow rail laid down on longitudinal sleepeis continuouslya matter of 40 years or so. Surely the disastrous results enunciated by your correspondent would have been rectified ere that, on what is admitted one of the finest railways in the world. A smoother I running permanent way has never been | laid with a corresponding absence of wear 1 and tear, and the system was only changed on the G.W.R. to the transverse sleeper one. when the double bull-headed rail was adopted from an economic point of view, with respect, to the load, and not the rolling-stock. Regarding the question of modern road-making, there is only one businesslike method to adopt—to find out what is the right class of road surfacing to layfrom a financial and engineering point of view—and that is test stretches laid under similar conditions of various materials and methods, in the sime district, and their cost wear, and life accurately tabulated. Stone, climate, foundations, physical and financial conditions, and la-st but not least, the nersoKal equation are so chameli-on-iike in their changes and varieties, that no one standard of construction should be rigidly laid down, and to this extent the theoretical axioms may well be found to be deficient unless largely diluted with practical ones.

L. G. P. Srvvrot