CORRESPONDING SOCIETIES. 317 



dusty in dry weather, and preferably a level, straight road; but if the road must 

 have curves or gradients, large radius curves and easy gradients. 



4. Heavy and fast motor-vehicles require a similar surface, provided it gives 

 sufficient adhesion on inclines; also easy curves and gradients and great strength 

 to withstand the heavy wheel-pressures. 



5. Very heavy slow motor-vehicles and traction-engines require very great 

 road strength, otherwise the deformation of the road in bad weather may be 

 so great that not only is the road seriously damaged, but the vehicle itself is 

 'stalled,' the action of the wheels in some cases being so great that on bad 

 roads the vehicle digs a species of pit through the action of the wheels rotating 

 in one place in their endeavour to force the vehicle along. This class of traffic 

 also requires bridges which are abnormally strong. 



Looked at from the point of view of the country at large, two interests are 

 very seriously involved. The first is that of the general commercial, manufac- 

 turing, and agricultural community, and of the carriers who desire cheap and 

 quick transport of goods; the second is that of the general community living 

 near the roads whose houses and land may be depreciated in value by the 

 dust and noise of traffic, and who, moreover, are taxed for the maintenance 

 of the roads of which the cost of upkeep rises as the quantity of motor traffic 

 increases. 



Many methods of adapting the roads to motor traffic have been tried— some 

 in the nature of palliatives and some in the nature of radical changes — and a 

 great number of experiments and observations have been made to determine the 

 effects of these various methods on resistance to traction, wear of road surfaces, 

 and the effect of dust-proofing or dust-laying materials, both as regards the road 

 itself and the effect of these materials on the surrounding land. 



Despite this, a very large amount remains to be done, and I suggest 

 that it is desirable to obtain further information on the following points : — 



1. The determination of what may be called the economical compromise 

 gradient for various districts, that is, the gradient which is the best compromise 

 between a perfectly level road requiring considerable alteration of road surface, 

 very expensive to carry out, and a road following the natural contours of the 

 ground, and consequently often forming very steep gradients expensive in horse- 

 flesh or motor power. 



2. The tractive force necessary on various gradients with various types of 

 road surface and conditions of weather. 



3. The advantage of various types of surfaces in resisting destruction by the 

 wheels of motors, in giving adhesion, and in preventing side-slip, combined with 

 tests of the quality of foothold that they provide for horses. 



4. The maximum cross-gradient that roads of various types may have without 

 becoming unsuitable for motor traffic. A perfectly flat road would be best for 

 motor traffic, but such a road devoid of cross-fall would not drain in wet 

 weather, and would probably get in bad condition, even if waterproofed by tar 

 or asphaltic dressings. 



5. The effect of various dust-laying materials on the trees and herbage adjoin- 

 ing the road and on the feet of horses using the road. 



6. The desirability of strengthening or rebuilding the older road bridges 

 which are now not available for very heavy traffic, in order that they may all 

 be capable of carrying heavy tractors of a fixed standard axle-weight. 



I also suggest that it is desirable to investigate the advantages of forming 

 motor-traffic roads which would connect all towns and large villages and should 

 intersect the country, so that no place might be more than a few miles from 

 one of these roads, except in districts where obviously traffic would not justify 

 this expenditure. 



Motor-traffic roads should be graded, aligned, and super-elevated at curves 

 with as much skill as is applied to the location and construction of a railway, 

 and it is desirable to inquire whether it would be possible to adapt the ordinary 

 roads to form these motor-traffic roads. 



So long ago as November 7, 1883, Mr. Alfred Holt, M.Inst.C.E., the well- 

 known Liverpool shipowner, was explaining and advocating his Lancashire 

 plateway scheme before the Liverpool Engineering Society. This plateway was 

 1910. Y 



