Effective Snow Clearance T RE icy spell of weather which has
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visited the western hemisphere again this year has brought further investigations, voluntary and compulsory, of the proper use of the snow plough, and of its design and adaptation. It is an appliance of the greatest value in rural areas, where traffic, although vital; is not sufficiently heavy to keep roads clear Moreover, it saves time and labour where drifted snow, as in deep 'cuttings, must be removed, or kept
at bay. .
The use of the plough is the commonest mechanical method of partial snow-clearance. Sometimes this is, perforce, done by angles and bull-dozers, The blunt blade angles of these implements cause considerable compression of.snow ahead of the blade, hardening the snow and limiting the depth which can be cleared at a single pass. The weight of the vehicles hardens the surface of the snow, making further clearance almost impossible and . frequently
unnecessary 1
If a plough of very acute blade angle be employed, the compression of snow is lessened considerably; such a plough would enable a heavy wheeled vehicle, equipped with chains on the driving wheels, to clear apath for itself in quite -appreciable depths of snow. The tip of such a plough is necessarily well ahead of the vehicle, and needs to be supported by a ski.
The front wheels, unless driven, will also need skis in deep light snow, in order that the vehicle shall be able to traverse a good depth of residual snow (Fig. 1). These skis should not be larger than from 1 to-2 sq.' ft. each, in order co compress the snow hard enough for the rear wheels to grip, and should be set as shown in Fig. 2. This will assist steering and form a fairly firm rut for the rear wheels which will heir to prevent sideslip.
Lane Widening Difficult
The width of lane to be cleared is a point which has to be considered, as, once a lane of some depth is cleared, widening it is not easy for two reasons; first, the ridge thrown up by ploughing and, second, the smooth surface of the residual snow once a few vehicles have passed! A plough wide enough to clear a two-vehicle lane would greatly handicap the plough-carrier,
One suggestion is the use of an asymmetric plough throw
ing a ridge to the left only (Fig. 3). • In general, it will probably be preferred to clear a single lane and widen it locally by hand, angle-dozer or other method. On roads wide enough to allow a centre ridge, two
separate lanes are the obvious solution. An adjustable plough, suitable for clezring a double lane, but capable of being ;narrowed to a single-lane width, is no doubt the best solution of the problem, as it would enable a vehicle to
sweep a double lane whenever conditions allow, and still retain the greater penetrating power of the single-lane plough where required
A road covered with deep light snow can often be rendered passable by driving a heavy vehicle over it. This could either bc a tracked vehicle, or a wheeled vehicle with good road grip such as a farm tractor with spade lugs or hard cleats on the driving wheels, and skis on the front wheels. This method would give firm ruts, but this can be avoided by making the vehicle push a large roller (preferably grooved or sheep-foot), resulting in a firm roadway with only shallow grooves or ruts. Where practicable, it would be -better to drive the tractor backwaids, to avoid the risk of the vehicle -lifting the front wheels and capsizing. If the pushed roller should prove unmanageable, it could be towed instead, with fairly good results, If skis for the front wheels be not available, the tractor will have to he driven bnkwards.
The breaking up of ice can often be done by harrows. The harrows should have vertical tines to avoid trouble with obstacles, and will need to be weighted considerably To protect drain grilles, cobbles, tram rails, etc. the harrow should be drawn by ropes only just strong enough to pull the harrow Over minor obstacles. The strength will have to be found experimentally; sashcord in multiple purchase should prove convenient both for ,experimenting and use, being not too hard to knot after rupture • .
The harrow must obviously be followed by a plough or sweeper to, remove the broken ice, and there is no reason why the sweeping vehicle should not itself carry the harrow, pulling it from an outrigger projecting forward.
The density of snow is given as 5 to It lb. per cubic ft. (Kemp's, 1946). In a depth of 3 ft., the lowest layer may well be compressed to 20 lb. per cubic ft.
It is suggested that a plough as shown in Figs. I and 3 be made of Hit mild steel, or 5/32-in, to h-in. duralumin plate, reinforced around the base and rear edges, by angle, and the thrust applied to a V-shaped member of say 3-in. deep channel, or I-beam placed about 12 Ms from the Iowa edge.