NON-SKID ROADS

Evening Post, Volume CXX, Issue 38, 13 August 1935, Page 11

NON-SKID ROADS

AN ELUSIVE;IDEAL

WO PERMANENT SOLUTION

EXPENSE THE BAR

Though/ the difficulty of.' obtaining .a permanent non-skid surface for .rural bituminous roads was emphasised at the conference of the New Zealand Society of Civil Engineers at Auckland .by Mr? F. M. Hanson, of Wellington, in a lengthy and very technical psfper, he gave it as his opinion f that 'there was no justification for constructing any of the more expensive types of pavement on 95 per cent, of the main highways of New Zealand. A non-skid, non-glare, hot-road-oil surface sealing'mat of naif in inch in thickness would meet all requirements outside city areas. The life of the halfinch non-skid mat was determined by the life of. the heavy'•. road oils', but, costing 9d to Is per square yard, this , type of ' surfacing would carry 1000 vehicles" per day; with .25 per; cent; of moderate weight lorry traffic for ,'at least "seven or "eight years. The. permanently non-Slippery road had so far eluded-'both British and American engineers,- brie of the difficulties being that its expense would make it pro : hibitive : for general application. . Excerpts from Mr. Hanson's reply to comments made during the discussion of his' paper are interesting, as they showi the extent to which non-skid roads may reduce road accidents so far as ,it is in the power of the engineer to do' so.- ---.;-•• CHIPPED SURFACE SAFER. The first section of the WellingtonParemata highway was paved with "high type" bituminous concrete, said Mr. Hanson, while the second, section was chipped "one-coat sealing. Under wet or frosty conditions very reduced speeds and extreme care were required in- driving over the. bituminous.... concrete, while high speeds, just as' on a dry summer day, could be maintained oh ' the? chipped surface, and brakes - could be applied without.fear of skidding. Test's were carried out by the Main Highways Board's traffic inspector in a car fitted with efficient and properly-adjusted brakes. On the chipped sealing the brakes could be applied'to their full extent at speeds of 45 miles per hour or greater, and .... the car showed no tendency to 'deviate from its course and remained under perfect control, but on the bitumin- . ous concrete arid smooth two-coat sealing, even under.dry conditions, brakes cbuld not be fully applied at speeds greater than 20 miles.per hour; it was necessary to release the brakes to bring the car back under control and prevent overturning or 'reversal of direction. Wet conditions made practically ', no difference to the non-skid properties of chipped surfaces, but the danger ."of smooth' bituminous roads when wet was well known to t all motorists. ' •'".' : ' ' Engineers all over the world appreciated the necessity for non-skid roads. It was stated: that skidding was the cause of 50-000 motor-vehicle accidents in the United States every year, and, though climatic conditions differed in New Zealand, a surface which would protect'the motorist from such hazards was essential. An iron grid at Seattle had resulted in not one skid acciderit in twelve, months, and tires shov/ed no. extra wear, though for the pfecedlrig' year.' 182" skid' accidents arid six.1, fatalities had occurred. '.■ '.:,■■-■-. SAVING SKIDS! ' '--'■> "■ Quoting Mr. A.' Ty'ndall's paper on motor accidents, "he made it plain that there 'were many contributory causes of accidents. A slightly-intoxicated driver on a drizzly evening, his windscreen: being blurred,.might driye at an excessive speed round a sharp curve having'little or no super-elevatipn, and as "a result his'car might skid off the wet, slippery pavement. The mishap, said Mr. Hanson, would no doubt be ■ attributed to the intoxication of the driver, but 'there were seven different factors which might, have contributed, and'if any one of those causes had not been present, no accident would'haye occurred. The engineer could have , prevented the sliding of the car off the road by' providing a non-skid surface. Although it was stated that 70 per. cent, of accidents occurred from causes'other than slippeririess, it was undoubtedly itrue that if all roads were non-skid, ivehicles could; stop within much shorter distances, with the result that '.many. accidents which were not' reported as due.to skidding would .not occur. ■'.' '. '. . ROUGHNESS MOST IMPORTANT. ;" With'the' increase in traffic, which tended to polish road surfaces, and the increase in oil drippings from cars, the-skidding on high-class pavements, was bound to assume greater proportions. The definite non-skid demand was" emphasised by "Lieutenant-Colonel" Hughes, of Hampshire, in a paper in .December last, in which he wrote that ,with the growth of fast mechanical i traffic, and an increasing \ use of sur- ■ face materials which were in themI selves waterproof, a roughened surface 'became more important than the dust- ' laying and long-life properties of road i surfaces. "AH road engineers," wrote : Colonel Hughes, "are endeavouring at (the present time to. obtain surfacings .which, once they are laid, will remain ; throughout their life in a non-skid conj dition without surface dressing, but we are far from reaching-finality in that 'direction. ; When one considers that in iHariipshire 'alone £125,000 a year is • spent on surface dressing, the greater Spart of ■which is required :for the puripdse of providing a "non-skid surface, lit will be realised that the best use _i must be made of the materials, arid the " jiongest possible life' should be obtained." .- •' ■■' , '■ ' ' ' '■■•"■'■ f In. regard to : tire Avear on chipped | roads, said Mr. Hanson, there was no j evidence of any difference in the wear ! on the' tires of two lorries in use in tth'e Wellington district, one of which 'operated entirely on chipped sealing, .'and the other on a two-coat smooth sealing. Even if there were evidence | of' slightly ' greater wear, motorists j would prefer that to the smooth bitum■inous surfaces. '