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I WHAT WILL BE THE ROAD CONSTRUCTION…

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I WHAT WILL BE THE ROAD CONSTRUCTION OF THE FUTUR'.E ? SIGNS are not, wanting, say Engineering, that the macadam- ised road is poomed as unsuitable to rapid traffic, owing to the in- convenience of dust. rrhe use of the heavy steam-roller robbed the macadamised road of its peculiar value, and made us familiar with the water-bound road. No one who can remember the discom- fort of consolidating a freshly- made road, in which itihe flints stood up in the most uncompro- mising fashion, and had to be forced into place by the wheels' of the passing vehicles, would rega rd the method of formation as ideal. The steam-roller did the wor.k expeditiously and produced rapid- ly a fine smooth road in appear- ance but it concealed evils against which McAdam obsti- mately fought. To get a finished appearance it was necessary to fill in the interstices with some form of packing, and a mud formed of loose earth soaked in water-that was anathema to McAdamâwas found a fatally easy method of overcoming what I was undoubtedly a weak poi nt in I the original plan. The cause of the excessive dust raised by motors on wateir-bound roacls is a matter of some uncertainty, or rather the proportion attributable to the [suction action under the tyres and that due to the driving wheels remains undecided. Pos- sibly the true destructive agent is a shearing force, developed be- tween the wheel and the -road, causing the wheel to act as a grindstone on the surface, in- creasing in efficiency with the speed of the car. A point of equal or greater importance is how to prevent the dust becom- ing a nuisance. Authorities do not look with favour on any so- called palliatives or surface treat- ments. What then, we are temp- ted to ask, will be the nature of the road of the f ature ? We know something of the conditions it will have to fulfil. It surface must be strong enough to resist the pressure of traffic without disintegration, and reduce friction to a minimum it must neither allow the formation of puddles holes, nor exude mud in wet weather and dust in dry. The camber will be reduced as far as possible, permitting the traffic to be uniformly distributed over the roadway; the surface must pre- vent skidding, and be suitable to both hoof traction and- wheel traction. Luxury will, no doubt, demand other qualities, such as silence, resilience, and an aesthe- tic appearance, while financial considerations will compel per- manency in character and econo- my in maintenance. Judging from recent experiment, it is not, adds Engineering, at all impos- sible but that these requirements will be fully met, and possibly some others of hardly less importance, by the adoption of a truly bound surface. The crust of the road will be held together by some pitchy or bituminous material, possessing such a de- gree of cohesion that water can- not penetrate. Bitumen is likely to answer better than pitch or tar, but bitumen needs careful selection. This material can be applied in various ways on diffe- rent foundations.

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