ROAD CONSTRUCTION

Dominion, Volume 13, Issue 200, 19 May 1920, Page 8

ROAD CONSTRUCTION

CITY ENGINEER'S OBSER-

" VATIONS

GREAT STATE HIGHWAYS

?', course .of a -.voluminous report to the City Council, the City Engineer (Mr. W. H. Morton) gives a mass of vnlu- ■\ able information on matters of concern ■ to municipalities, gleaned during his re- . cent visit to Canada) tho 'United States, ■ United Kingdom, and the Continent. Chief „among- the problems, every local feody is faced with is road construction ; in relation 'to - modern'-: forms' of traffic. :' Mr. Morton deals with this subject in- • follows:— . ■ ."I had. not been long in America when I was forced:to the conclusion that,one of the principal maitte'rs for consideration ■ and investigation was the method of - road construction, more particularly in tho-cities. - In practically tho wholo of the cities of Smorica wood 'blocks, gran■'ite setts, and bricks are'to be found in' '. use for street -paving, but for general •city work tho use of bituminous asphalt i predominates 'm business thoroughfares, ■ and-in the best residential streets. At the approaches to wharves and railway .' stations'which are subject to heavy and • 6low-niovmg traffic granite setts or wood ;■ Blocks are mostly used for street 'pave-

: : ments. ■'. ' ' '. ', "The. wood pavements are generally oi |; blocks laid on a principle somewhat sitni- ; ''lar to the wood pavements of this city, 'but the timber used 'Is that known-in f. Australasians Oregon pine, but through•out America as Douglas fir. In America, however, the wood pavements:did not ) aopear to be very satisfactory, innumer-able-instances of irregularities and 'de'■pressions being. found. ■ Without doubt .'• tnTpavement whfcli finds most favour for :/ streotwork is sh(\t asphalt and bifamin- '■ ous concrete, which latter is varied some- • what in' different places, and 'variously ' known as bitulithic, Topeka mix, and \ Warrenite.- When referring to this maI : terial afterwards the ■ tcrnr bituminouf .'■' concrete will bo used as such' more clearly :. indicates the nature of the material. i. "One of. the principalthoroughfnres oi New York, Fifth Avenue, is paved with r sheet asphalt, and; notwithstanding the 'heavy and fast-moving traffic (including ■: "motor-buses in great numbers), this ma'.'terial appeared to great advantage, being ,- miier,sanitary, and not slippery. It was i--distinctly noticeable how.few horses were • engaged in cartage of any; description, '.'. more particularly in the Western States. I'was informed on good authority that in California there 19 one motor vehicle ', to' every seven of the population, and it .does not take one long to believe that I the statement -is absolutely correct. I Horses were scarcely ever to be spen, ex- ; .■ cepting-only in the vicinity of dockyards, r The result .is that, so far as rnadsur- '■■. faces are concerned, horse traffic 'has • Keen" eliminated from consideration. This i:'.. simplifies to a very great extent the dir- |; ficiiUlw" to bo overcome as compared if- with those met with in a city where the ': traffic is in a transition stage, and where ! ; consideration has >to be given to fast- '!■■. moving motor vehicles, which cause coni siderable damage to . water-bound ' mai"' cadam-road surfaces, and,where at the i, same.time there must be a surface which > .will not be so'slippery 'as to prevent : horses getting si grip of it. ' . !y. State Highways. ■ '""The ' State highways constructed by |> the counties in the various States are ! In many instances of a wonderful char- • actor. -For instance, in Portland, Orc- ;'■•'■■ son, I -was driven over the Columbia ' River Highway. This extends for fifty • miles from the town of Portland to the ■'■ Columbia River, and then along the .. banks'of this magnificent river for many miles.' This highway, however, seemed !:•' to be used principally for pleasure pnr- , poses, there being at the time of my visit scarcely any traffic other than or- ; dirart-touring automobiles'. -The pnv- : ing is_of_ Warrenite or bituminous con- ;.' cfete,' about 24 feet in width, and with a surf ace.; particularly even and satisfac- |' torv for motor traffic. The money spent , ; - upon; its 1 construction was considerable !-' (ab0ut.,£275,000).,. There are very many ; expensive. structures of concrete in.re- ; tainirig walls and bridges, designed to i the; -road to be carried past ',-. ravines and*over streams, and which are ;'. extremely interesting. '•--•■-■---Concrete Roads. j': >-"In many .parts of California as Well • as ia Wayne County near Detroit and '■■ elsewhere, great use has been made of .'■ concrete for road construction. The con- : crete-'invariably is not reinforced. After ;■ travelling over hundreds,of miles of such ; roads, the conclusion .was forced upon 'one":that thev.were eminently suitable :. 'for'motor traffic provided that the foun- . datioif on which -they were constructed 'jrasfabsolutely firm and rigid. In only one place, outside of Los.Angeles, was mv attention drawn to* defective : piece of road made of this material, and the -defect was clearly due to the nnsatisfoc- ■ tory nature of the sub-foundation. The width; of','the concrete roadways varied ; from ,;12 feel to 20 feet. It was not considered;necessary.'to increase 'the width . .-beyond-20ft., since a third line of : ~v.ehiales;.could not be accommodated unless the width were made at least 28ft.. and from--observations . made there could be "no'doubt that, for highways, "room for two vehicle:? to pass comfortably- is all that is necessary, and 20ft. . easily, meets this requirement. The material 'in;the concrete■ roads requires to be of. .the ..best description. A rich mixture is' used, and great, care is taken to prevent any voids occurring. - One coat ' Kork.js.ji.ow generally accepted as being most satisfactory. The depth varies according to local conditions, and may on 'the average be put down as 7\ inches, ■although- in some instances ' a depth of eight- or nine inches ■ has been provided. TJh'e surface' is generally ■finished' off witk'V long-handled roller's rolling from one side of the road to the other, and by. means of a belt drawn across the _ surfaea.. AlMiough provision for expansion is. made on nearlyfall such • many crack's are viable. These "are'' invariably duo to temperature stresses. No notice is taken of th;m, and, they are .remedied by pouring in ' bitumen when, at their greatest width in order io prevent deterioration of tho' concrete at the edges. " Granite Sett Pavements. ' "Granits sett pavements are to be found , on the approaches to all wharves, Tail- / way, and goods stations, and, so far as .' lasting qualities are concerned,'give a better result than any other class of material. They are, however, not so sanitary and do not form an ideal surface for present-day traffic. Brick Pavements.' "Brick pavements weTe in many cities uneven in character and unsatisfactory. These were, however, originally laid over a concrete foundation on a sand cushion. A more recent practice has been, to lay the bricks directly on tho concrete bedding and grouting them in with cement mortar, in such a way that they become part of a homogeneous mass, comprising both brick and concrete. This method, which I naw particularly in Seattle, appeared to'be highly satisfactory. The roads had not been subjected to great tests; but there appeared to be no doubt that they would satisfactorily withstand motor-car traffic of all descriptions. The bricks were of a special character, burnt very hard, and specially mado for this olass of work. ; Wood Pavements. "The wood pavements are similar in almost every respect to those laid in •Oils and other countries. No special mention, therefore, requires far"'be made except to-say'that in my opinion the use of soft wood whethei creosoted or untreated for street-paving. purposes is '•nofci as satisfactory as the use of hard woods, when subject to heavy traffic and if properly laid. ' They are subject to the same difficulties which ariso from ! expansion and contraction, and which constitute cne of the greatest troubles in : dealing with pavemsnts of .this 1 descrip;tibn.. ■-■ Water-bound Macadamised Roads. "''■"'ln soarcely any of the American cities visited were any water-bound macadamised roads, to be observed, which were- better than similar roads constructed in cities of Now Zealand. As a matter of fact where the roads surfaces and not been paved with .permanent material, such as street asphalt, bitii T minous concrete, woodblooks,' bricks, or

granite setts the roads were in very bad conditio!" indeed, most of them having an earth surface. Where such was the ca36 kerbing, guttering, and footways wero i-i an equally bad condition, ninny of tho streets having for a footway simply a few planks fastened together and laid in much the same way ns the duckwalks used in Hie trenches during the recent war. On making inquiries as io how sueli a stub of affairs existed,wherein sonio streets were paved with tho most expensive and permanent material.', ami others were left in a deplorable condition, it >vas at once ascertained, that the method of financing pormanont . pavement construction vns the sole reason.