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Preparing for the Worst
Page 95
Page 96
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WHILE the London to Birmingham motorway was still under construction, the Ministry of Transport were developing special vehicles-and an organization to keep the new road safe for traffic in all weathers. A plan which has been worked out with the surveyors of the four main counties through which the motorway passes concerns bulk gritting vehicles operating at speeds hitherto unknown for this work in Britain, and aims for complete gritting of both carriageways of the 50-mile road in 30 minutes.
The Atkinson, Scammell and Douglas chassis to be used for this work were described in The Commercial Motor on November 13, 1959. The 12 bulk gritters to be used initially are being produced to the order of the Ministry, and they will be stationed along the motorway for operation by the maintenance staffs of the four local authorities. To accommodate the vehicles, maintenance compounds are provided in each of five service areas approximately 12 miles apart along the MI.
The four county authorities concerned are Northamptonshire, Buckinghamshire, Bedfordshire and Hertfordshire. Two maintenance compounds fall in the section of motorway covered by Northants, and one comes under the control of each of the other counties. Disposition of equipment is, at the outset, to be three gritters at the two maintenance compounds at each end of the motorway, and two at each of the three remainine corn pounds.
The eight-wheeled gritting vehicles are designed to carry 14 tons of material, whilst the six-wheelers, which are being produced by Douglas Equipment, Ltd., are of semi-lightweight .construction incorporating plastics bodywork in place of steel. They will carry nearly the same payload as the larger vehicles.
14-ton Capacity Although the Ministry have provided large gritters for use on trunk roads throughout the country for some time, they have not -sponsored vehicles of this size before. A capacity of 14 tons is required to enable the vehicles to spread grit From one maintenance compound to another without the need to reload, as it is lot practicable to recharge vehicles on the road and unladen mileage must be cut to the minimum.
Operating in the centre lane of the 36-ft.-wide carriageways, the vehicles will spread grit or salt at the rate of about I ton per mile and at an average density of 2 oz. to the sq. yd. over the road surface.
This is a fairly light density of spread. but it will prove quicker and safer to cover the same stretch twice, if necessary, than to grit heavily and fail to complete a 12-mile section. The maximum speed at which the gritters will be able to operate is thought to be about 30 m.p.h., as above this speed windflow around the vehicle prevents proper sideways dispersal of the grit.
However, under certain conditions it will be possible to operate at up to 40 m.p.h. This compares with the accepted normal gritting speed for lighter vehicles used in this country of 10-15 m.p.h. The large vehicles will be used only for the main motorway. Gritting of slip roads, approach roads and service areas will be carried out by Atkinson 2-ton trailer gritters.
Areas of responsibility have been deliberately kept flexible in the plan by which the four authorities cover the motorway. Each authority's section of road does not necessarily end at the county boundary so far as gritting is concerned. Maintenance compounds will be treated as staging posts, and one authority's vehicle will be able to use other areas as turnround and refill points if necessary.
The maintenance compounds provide garaging facilities for the vehicles, and outside storage space and hoppers for high-speed loading of gritting material. Ordinary road-maintenance equipment will be kept in the compounds also, and the county staff will be responsible for all the operations carried out from the depot.
Outside storage space for 2,000 tons of gritting material is being provided, whilst twin 45-ft.-high hoppers will hold 120 tans of grit and salt for immediate use. The hoppers are constructed in concrete and loaded through a chute feeding an auto
made elevator. They are part-lined on the inside with glazed tiles to prevent 'clogging, and are discharged through gravity chutes. By this means a 14-ton vehicle will be loaded in a minute by the driver.
Some of the drivers for the new vehicles will be specially recruited, whilst the others will be taken from the existing roadmaintenance staffs of the county councils. All will be specially trained by the• Ministry both in driving a 24-ion-gross gritter at 30-40 m.p.h. and in gritting and snow-clearing techniques (the vehicles may be fitted also with snowploughs).
During the training programme, the . gritting apparatus on the vehicles will be individually calibrated to suit the•tYpe of grit to he used by the local authorities with whom they will serve. It is expected ihat 50-60 men will be trained in the first place. They Will include reserve drivers as, in really difficult weather, operations will have to be sustained for long periods. Overnight accommodation is provided in the maintenance compounds.
Reversible Plough
Each vehicle will have a standard mounting plate attached to the front of the chassis to take a reversible angleblade plough. The chassis members arc extended, boxed and flitch-plated at the Front for this purpose. The plough runs on large casters tO keep i+ just elear of the road surface, and incorporates features developed by the Road Research Laboratory.
It is hoped that it will be possible to plough 6-in.-deep snow at up to 30 m.p.h., whilst at 20 m.p.h. and upward the ploughed snow will be thrown 12 ft., making it possible to shift snow direct from the centre lane on to the road verge.
With the conventional design, there is a gap between the plough and the road but a rubber lower edge is being developed for these ploughs to give a squeegee effect for complete snow clearance. V-shaped blades for heavy ploughing will also be available, and Douglas four-wheel-drive chassis fitted with Rolba or. AEB1 fotary-tyrre snow blowers will deal with drifts.
However, they may be needed only in exceptionally severe conditions as the whole essence of the plan worked out by the Ministry and the surveyors is that all the measures taken should be preventive rather than remedial. It is not intended to wait for ice to form or snow to fall before taking action.
Commencement of operations will be governed by close association with the Meteorological Office, by reports from patrols on the road and, above all, by local knowledge. Thus, on receipt of a frost warning, the gritters will be out to offset its effects by putting down salt to prevent the formation of ice.
If the simple angled snowploughs are to be effective, they must start work early, and certainly before the deposit is more than 6 in. deep. In emergencies, inter communication between road patrols, gritting -Vehicles and the service areas will be by the police telephones which are situated at one-mile intervals along the motorway. With this facility 'available, it is not considered necessary to go to the expense and 'complication of installing radio-control equipment.
Picking Up Grit
, The third operation, which will be complementary, to gritting and ploughing, is picking up the grit sPread, which, at the .high speeds commonplace on the motorway,. could, well be dangerous, causing damage to vehicles and particularly to windscreens.
As no vehicles are manufactured in this country specifically for collecting grit on this kale, two ,collectors are being imported from Switzerland and Germany. The Swiss machine is a Streicher and the German a Faun. I3oth operate on the same principle, being towed by a tipping lorry, into' which they discharge their-sweepings. Several lorries will be required to operate with them as they can pick up 12-16 tons of grit per hour at a sweeping speed 'of 21-4 m.p.h. ,
Although such a low 'speed might seem dangerous on the motorway, being almost equivalent to a stopped and there. fore forbidden vehicle, it should be remembered that grit tends to collect in the gutter and the collectors will work only in the near-side lane.
They will be clearly, marked and less frequently used than other vehicles, being required only in breaks between cold spells. and, more intensively, in the spring for,a general dean-up. That they are essential is shown by experience on the German Autobahn, where it has been found that up to 60 tons of grit per mile has to be collected in the spring.
The vehicles which will carry out the gritting and ploughing operations incorporate a number of special refinements. On the 8 x 6 vehicles, twin 7-ton gritting bodies are mounted in tandem feeding towards thz centre on to a pair of vaned spinners. These are side by side just in front of the forward wheels of the rear bogie. The bodies are of conventional pattern, having V-form upper sides which become vertical at the bottom to make a trough in which runs a slow-moving endless belt. The belt is driven by chain and reduction gearing from a power takeoff at the rear of the transfer box of the main transmission.
As belt speed and the flow of grit must be matched to road speed, an airoperated auxiliary gearbox alters the power-take-off ratio so as to conform with the gear engaged in the transfer box. The two spinners are required to rotate at a constant rate irrespective of road speed to give a uniform width of spread.
They are turned by gear-type hydraulic motors powered from a pump driven by the vehicle engine. A pressure-relief valve is fitted in the system, and the requisite pressure to rotate the spinners at the set speed is maintained at all normal engine speeds. These features were devised by Atkinson's Agricultural Appliances, Ltd., who are building the bodies and equipment for all the vehicles. Similar 'gritting gear is used for the Douglas 6 x 6 chassis, but in this case a single 12-ton body made from plastics is to be employed. • '
. As the spinners are mounted within the wheelbase, the gritter will prepare a path for its own rear wheels and, to a certain extent, throw grit tinder the front wheels. This advantage is slightly offset by the fact that with mid-mounted spinners it is not so obvious to following or overtaking traffic that gritting is in progress. To warn other traffic of this, "Gritting" is written on the rear of the body in 1-ft.-high letters of reflector material. When the vehicle is not working, the sign is obscured. Lamps are positioned at -each side of the vehicle to illuminate the spray of grit after dark.
• To allow vehicles to overtake without getting "shot-blasted," flaps are provided beside each spinner to deflectits output and keep the grit within the track of the vehicle. The flaps are air-operated and controlled from the driver's cab. Reflector arrows at the lower rear quarters of the body point to the grit sprays.
With so many auxiliaries to be controlled, a special layout had to be devised for the interior of the forward-control cabs which, incidentally, will have reverse-slope windscreens to prevent build-up of snow and ice. The theory behind the cab-instrument layout is that the less important controls• should be removed from the driver's immediate line of sight to avoid unnecessary distraction.
Instrument Clusters • _ Thus, the radiator temperature gauge, oil-pressure gauge, air-pressure gauge and 'ammeter are positioned in a panel above the windscreen.
The speedometer, clock and fuel gauge are all-important instruments, as -timed schedules' will be observed and a stop on the motorway because of fuel shortage could be serious. They are mounted in a panel directly in the driver's line orsight.
Frequently used controls such as the flap switch, warning light switch and a headlamp flasher (to augmentthe horn), are immediately• under the driVer's right hand. •