THE ROAD QUESTION.

Press, Volume XLIX, Issue 14667, 16 May 1913, Page 4

THE ROAD QUESTION.

TO THB* EDITOR OJf 'TUB MtESS." Sir, —Some strong adverse comments are being made with regard to the methods that have been adopted in the new road formation that is taking place in Manchester street, between the Clock Tower and tho ra ; l\vay station. As this work is being dono in direct violation of tho latest canons of road formation, one cannot wonder at these expressions of opinion. In support of these contentions, and in view of the fact that the subject of road formation i 3 ono of cqnsiderablo interest to tho Christchurch, public at this juncture, when a comprehensive road scheme ia under review, I propose, with your permission, to quote at some length the latest views of an export upon this very important matter. Mr W. H. Maxwell, n gentleman whoso authority is unquestionable, in an article in the last October number of "Caseier's Magazine," gives some valuable 'Information and suggestions on tho subject of road-formation and upkeep.

Ho .—"During the motor boom of recent years, tar macadam been referred to in tho Press nnd ekewhere as a new and improved form of road construction! This is in do sen<=e correct, Tar macadam has been rc-ularlv made and used for roadways ami footways in Tunbridge, «"?;?"•; xnanv other towns for tho last thirtj years, or more, and its -faults axi.l vi-tues hare, therefore, boon tested uy lon- experience. In tho minds of some, tar macadam is to bo tho imivcrsamedicine for all bad roads, but any such opinion is tho result of defective knowledge and experience. This inn terial, when properly prepared, and <'. a suitable aggregate, is a very £ 00 ' thing w"cn laid \mder proper conditions, and in a suitable position, but. :l must not be looked upon as a panacea for all corts anc * conditions of roadTar macadam makes a very excellent rcadwav, when well laid on a good, strong" foundation, in districts- where tho traffic passing over it is not too heavy, but here, again, the work v expensive. "It must be remembered that tar macadam is of a plastic nature, and that even when laid, it is greatly affected by tho tcmperaJuy*. On a hot day, though it may hare been laid many mouths, the heat of tho sun, to feomo extent, liquifies the tar, with which the material is mijed. that tho surface becomes slightly plastic and yielding. "Another featuro is that the laying and rena'rs of tar macadam cannot satisfactorily bo done during wor, weather, or during cold winter months. If tlio work is carried out during feuch times, there is a great risk of too much tar being put with tho material, and this will cause- much trouble- later on in hot weather.

"Before applying (ar to a road surface, the latter should bo put into a thoroughly good state of repair, ami r.llowcd to set and beconio trull consolidated. "Jfc is essential for good work that tho road surface should he 'bone-dry' for a depth of about 2in, as tho tar will be much less likely to work up ana disintegrate under tho traffic during hot weather.

"Of all infiterials available from timeto timo for tho treatment of roads, tho uso of good coal tar, after cuitnblo preparation, has best withstood the test of t ; mc, and has, consequently, to a very largo extent, superseded mostother methods of Mirfaco dressing."

Mr Maxwell, as will be scon from tho foregoing quotations, is strongly in favour of the uso of tar for road formation, but lie does not let his predilections in that direction pet tho better of his judgment. Ho exorcises a wiso discretion in tho uso of tar, and avoids the wasteful methods of those who bury this voluablo commodity where it is worse- than useless. Among other valuablo information ho gives his idea as to how tho best general purpose road should be formed: "To withstand heavy traffic of all kinds, both mechanical and horse, to give good foothold and freedom from slipperiness in all weathers, to bo serviceable and reparable in all seasons, and taking into account reasonableness of prieo, thoro is nothing better for the general run of roadways than a goo-l granite-metalled rondway surface bound with clippings of tho same material, laid upon a good, strong foundation, and subsequently, when thoroughly settled, hot tar painted on tho surface and finally sprinkled with granito grit of gto Jin gauge." On tho subject of dustless roads Mr Maxwell, after saying that these exist only in tho mliids of theorists goes on to say that in tho actual work of construction and maintenance tho engineer can do a groat deal towards reducing tho evil to a minimum by attention to such matters as the following:—l. Tho uso of the hardest and most durable metalling. 2. Tho eiliciont draining of roads, which am usually wet or damp, by n;flod sub-soil drainage. 3- Tho consolidation of the best metalling by the aid of a limited supply of suitable "binding , ' such as granite siftings, or a bituminous binder such as fir.o grade macadam. 4. In some cases where suitable conditions obtain, and tho traffic is not too heavy, by constructing tho wearing surfaco with about 4Jin of tar-macadam laid upon a solid and reliable foundation. 5' By annually tar-painting and sprinkling with granite screenings existing macadam surfaces in cases whore they aro in a good state of repair. 6. By keoping the 'road surfaces well maintained to a good, contour, smooth and even surface, and well drained. 7. By making and keeping the wearing surface of the roadway as impervious to moisture as possible. To revert now to the work that has been, and is still going on in Manchester street. All the above conditions are cither ignored or violated. The only foundation tho' road had has been torn up and carted away. Tho new material, which is altogether unsuitable for a bottom layer, is being dumced upon a soft, and during part of its nrogress, slushy. loam bed. This tar-macadam is being laid in tho -wrong season of the year, and during the worst conditions of s\ich a season; and then there is tho fact that costly material is being buried whero its presence will be rather injurious than otherwise.* Tho result of all this must bo that, after a short time, owing to the presence of this plastic material without foundation. Manchester street will again assume that undnlnting or corrugated appearance for which it has so long been notorious. Of courso these defects may grad-.t-nllv bo rectified, and tho road surface brought to a somewhat satisfactory condition ; but that can only bo after a long period of consolidation, and a enstly process of patching and topdressing with small tar-mscadam- A great deal of the expense involved in this slow progress towards a permanently satisfactory condition would be

moSL hj th ° " d °P tion of rational nietnods now.—Yours etc May 3th. MACADAM.