ROAD-MAKING

Dominion, Volume 7, Issue 2184, 24 June 1914, Page 5

ROAD-MAKING

4— ' EXPERIMENTS 1 LONDON MR. F. W. FURKERT INTER. VIEWED SYSTEMS OLD & NEW SUPPORT GIVEN TO WOODPAY INC, As the representative of New Zealand at the International Congress of Road Engineers he.id in Lcadoß last year, Mr. £. \V. Fiirkcrt, 'fasjreirting Eiigincer of the Public Works Department, iiad exceptional opportunities of observing the street and road-making systems of tho United Kingdom. and in the oMestablished countries on the Cont-iiient,. and of ascertaining tlio last word to date on a subject that is, and must ever be, in a youflg country like New Zealand, of the very great-fist i-in.port-anco and interest. "Whe-n ajlscd by ii. reporter to give some information wfiieh might be of interest licre,' Mr. Furktsrt agreed to do so. Experiment® in London. "In 1911," said Mr. Farkert, "a large number of experimental lengths ef soad were laid down at Sidcup, in &nt, and in the Boroughs of VVa)]dsw«rtii and Fulliam, in the comity of London. These, sections were laid, by many , di&rent persons, companies, aiid corporations, cach convinced "that- Jjis or their pare* went would prove the best. The object: which the board ill control of roads Had in view was to secure ft se/vice test wider uniform conditions of 3, number of; trial lengths of roadway laid dowUi under the general direction arid Stfpervi-; sion of tiie AdvisoTy Engineering Qotn* inittee of the Board, so tlia't a rccorcl o.f comparative results- -.could be obtained ina 'better v and more reliable rfian-jier than is generally obtainable in the eaae of' road surfaces laid dovvii in t&e ordiua-ry' 'course of road mainien-aiico in different parts of the country, "The scheme for laying, down the trial, sections Was framed so as te ensure that they should bs constructed and maintained in precisely the smio manner as road surface work laid down liador normal service conditions, except that the Road Board proviilcd tiio money, and all work of construction and maintenance is subjoot to tha ge-iicial supervision of the Advisory Engineering Committee of the Hoard. Almost- a mile was laid at Sidcup, a locality chosen bccause.it approached neamt to .what might be termed average conditions. Judged by New ZealaM standards, that, would.be classed as fairly heavy tftifficconditions, a tally taken in 1910 giving over 2500. tons' prr day, equalling 4SO tons per yard of width. About 900 yards were laid in Wandsworth on the road through ICing.uon Vaie. There the traffic statistics give an avefage- of SJOO tons per day, eqnalliisg 522 tons per yard width. About t.fee sa.tt)e length was laid down in tlje Fttlhsm, where the traffic was lighter, with nearly 60 per cent, of heavy bars# wagons, giving 2171 tons per day, or 281 tons per yard width of road.

"Though the time, is wot yet. rips," continued Mr. Furkeil "far a iisai pro a nounccment as to -the most ecoiwmieal surface consistent with satisfaction, the general indications lip to date af€ be' mg carefully watclied, siul cnginfteis from every civilised country represented at the International Mand Congress visitcd-the' experimental sections a.nd Btudied their condition.

"The Advisory _ Knsinming Committee supplied' an infefim every section, gifits - first -ee'st, extent, character iiiiid materials, cost of repairs, conditio® in winter and saamer, rate of wear, life (if worn ant), and total cost,, including repairs p3f super yard per annum diiritrs fife. This information will be kept ijp to date aftct reported in similar form to each succeeding, conference until'all Wic competing sections shall have been worn out, .when .'definite hifeftsttan tffll bo available as to the annual cost flf a road ,in each materia.!; annual cost i»1 eluding first cost, plus in-west dhided by length of life, .and ivitli all expenses for repairs and.new materia! used annually added.

Materials Used and General Results. "A definite statement as id any one system itscd in the oyjiffiroertta.! Motions bring superior, omid ftnt,'' said Mr. Furkort, "at this stage b<? given. There' was, however, sifffickflt data and evidence available to justify a • general opinion being expressed* Watervbotrnd Macadam, composed of Cornish granite,, with granite chips and flust for binding, only lasted 15 months and tot 20. 4d. and 2s. 6d. per yard per annum. The following list ef materials o»_ trial ■at Sidcup may be of interest:—Watcrbound Macadam, single and dotibte avid pitch-grouted Macadam, Durax ar■moured paving, feand wi-ft plascom, surfacing with Comastsk, tar Macadam, tar Slag Macadam, Tarmac,, roadoletim asphalt (thisw:.is bo tcood said Sir. Furkert in pas.slDg), Bseotwc; Tarvia Macadam, Itoadainaflt, iLititomac, Pitchmac, ftat-tjisU asphalt, asphalt Macadam, and Trinidad asphalt Macadam. Up to the present, those sections laid with various ferns of natural asphalt (Val de Travus, Limner, and Trinidad), seem the best, and have cost almost nothing for repairs. In Wandsworth, tar slag jfaoatlfrm, Taf» mac,, bituminous Macntlm:, and pitch' mac' (Brodie's system) were used, and all these sections eo far .look very well. At Fulham the sections were laid with ' various classes of rock bound with bituminous matrix containing varying pro portions ■ of bitunwi and' tar cdmptt, and with slag and clinker 'similarly bound. .All 1 these sactio'ns are in good order, find so far bate cost almost -nothing for repairs, Thosu frith the larger proportions of tar scrim least satisfactory." . IWood-blocli Streets. Asked if his observations had led hir.i to any conclusions en ilio subject of wood-bjocking. as a material, of road formation in general, nnd its worth' as compared with asphalt in particular, Mr. Furkert replied; "1 wa&'majcli. struck with the feeling obtaining amottgst «&• ginoers at the congress fiat soft Wood treated with preservatives' was prtifei" able to hardwood fo.r blocking toaia. Somo of thn hardwood block pavements have given rise ■ to unfavourable' comment hy reason of their tendency to become 'cobbly.' This has not been found the caso in the colonies, because, ' probably,, otti ■ practice favours close-jointing, thereby supporting the edges; whilst English and Continental practice, especially a few years ago, favoured .laying tto blocks with a'ti appreciable space between them, aftop wards grouting, either 'with cement at somo bituminous compound. Under this method there ivas a 'toaefeiie.y for the edges of the blocks tg get worn, and so form a corrugation.'' Wood for Concentrated Traffic!. With regard to the vesed question of' wood blocks versus asphalt <xr hi.tuminous pavement, Mr. i'urkert said that though for niodeiaiolv heavy ti-affic it was dilticult to $ii;y that blocks were better than natural asphalt, or vice versa, when we come to 10.-illy heavy and concentrated frame, espfici.llly where wheels are ctrjipeilssi to follow Approximately th.e »aii:e track, the blocks show up stigeriar owing to the tendency of the asphalt fa work up into ridges. Asphalt also, has n tendency to become wavy under vtitg heavy motor traffic. Blocking has neither of these faults. For really intense. traffic, added Mr. Furkert iii this cojinection, nothing but sto®s settts, such as are used on the crossings Sa Wei-

i lii-iftorn where there is great coMMstton jof trajliir, will st»nd. ' . I New Systonis of Paulng. j Ocmtinm-ng on the genwa.l subjoct of . Mt-p-rn iwg, .sir, f-'uriiei t said that a iiciy system of paving had been i-ntro-UttcM in KnjrJkuid, KiMiWn as the Litkojalt block paving. This consisted of blocks pjc-pawl from natural rock aspb«iU, tHo similar to tlic oon.t '« tjuacn. Street, Auckland, and Mattray c- 101 , Dim :din, but of a htuul.y sizy for laying without skill-eel labour. Wrests bk't'Ks. about- two inches thick, are laid on this flat, jMst as bricks would lj£i laid, and then g.rojtwl to fill any m-icvciinesses in the-' joints. They were very exact, and made an extremely closf! joint, llie great advaiitago lay ■in the absence, of t-He need for heating apparatus or sjiecially-trained iabour. Another mfetbod wtw the W'ostrumrtn asphalt -system. This ivas, simrth'. a system in wliich tile bituminous binder was. dissolved in a volatile liquid. The rock aggregate, preferably of a slightly jjsro-ns nature, tvas mixed with the liquid, coldj in - -an ordinary concreto mixw, and applied ta tho road-, in the usual way a«f mßed. I-ii A few days . the. volatile matter had sufficiently evaporated to leave the road fit four use, and after further consolidation under a little- traffic it- made a perfect snr- ■ iaco, soft enough in the cofest weatlior I'.i allow a good grig., hut not soft enough to corrugate in hat waather. The oldoat sections of this form of road suri'rii'o observed by Mr. Furkert had beei- down for ever two years, and wore Wistmguishahfo from tne present sea-son's work.. There had been no cost for repairs., Approximately a hundred thousand square yards- had been laid in Anttferp, and that city last year laid, ill ■ the most heavily' trafficked streets, two sectioii-s»-one id Weslrtunito ana ■ one in Xouchato! aspiialt—and on the comparative behaviours, viewed in con- . nection with price, will be decided the ■ method of re-paving a number of the !■ principal streets.. Mil. Rtiaii Engineers Commended. "The statement lately made thai, our New JJfiaianel road engineers are hehin.d the times," said Mr. li'arkert, iti cftn- ; clu-dtafi the iiiterviovv. "is.'not borne out by my observations, which covered the streets of scorcs of cities and thousands of miles of roads ill. ill parts, of ■ the British Isles, France, Jlclgium, Holland, CSetittnnj-, Switzerland, Italy, Norway, Egypt, United States of America', Canada, and other countries. The exceptionally fine- road-s of Ewgia.nd and France am, due hot so mucli to any Magic ptiwef coittaiired tn the Kip-to-ilateness «l their engineers, but to tbi; laundations laid bv liundtofis, and in somo eases even tliotliia.iids of years of cmisolidatioii nnder •' tTaffic, with, in plate's, feet of metal; and to the immense. sums spent in mainteuance. Ailother potent factor is the character of the labonr available- for inainienaiiefi. In a- Souiig country like New Zealand, with its ■ opportunities for, change and advancement, we do Hot have the same wen year-' after year engaged on' the . <;trae sectioii of road, eonseqaently the now men have to be employed Some time- be-I'o.r-ff- they can ks- taught the best methods for a particular district: oi' lenß'tii of road, Nest- year fresh men have probably to be trained. lit alder countries, 'once a roid-nionder alii ays a road-mender,' the work even passing from iatln'i to son. lii France, espcciaily. great a-ttentien is paid to tire ti'ftiiviiigk of foremen, who '' are generally titne-ex.pired non-commis-sioned cfii('-"Ts from tiie engineer eorp?, tferr military training being <rf gtent va-iio ill teetiicating the pr.irtke -of exact attention to the details of ictst'ruc'tifms. In most European couutries the engineers in charge of roads iqti-sfc ha praciica} in en, liaw studied the siibjeet tliorou(rlilylfor''ii 'nuili' ; ■ '.her of years at recogniseel centres n# learnina:, awl have oblained ,an on-giiic-?r's diploma."