THE BIGGER THE LOA THE MORE THE BENEFIT
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By Our Midlands Representative
SOME 10 days before the motorway was opened 1 rode in the cab of a laden six-wheeler on a routine night run front Birmingham to London on the A5 route. The object of the exercise was to obtain data and impressions for a comparison with a trip in a heavy vehicle on the motorway route as soon as possible after the opening. This run was completed on November 3, starting at 4 a.m.
Before the motorway was opened many operators thought that little would be saved by a heavy vehicle using Ml, rather than travelling on A5 at speeds abnve the legal maximum. They believed much traffic would transfer from A5 to M1 and that the higher average speeds then attainable during the day on the old route would largely offset the advantages of the motorway. Many concerns were expected to continue to use AS on both day and night runs.
Greatest advantage of the motorway would, it was envisaged, be the predictability of traffic conditions. This might be a decisive factor when departure times could not be planned to coincide with the lightest traffic.
Governed Speed
Many maximum-load eight-wheelers are limited by the governor to about 30 m.p.h. Few of the faster multi-wheelers can achieve much more than 40 m.p.h., but this gives an easy cruising speed of 36-37 m.p.h., which, operators said, experienced drivers would not exceed continuously on the motorway.
On a normal week-day without fog or ice, traffic congestion during the day over the entire AS route originally added at least 14 hours to the overall running time, compared with a night run, but the loss of time was difficult to forecast, A t night, congestion did not, as a rule, account for more than, say, 10 minutes of the running time if deliveries were made in the early hours of the morning.
One of the prime causes of delay is the need for a lorry to travel at a
reduced speed behind a slower vehicle on a gradient, because there is not space in which to overtake. A balk at the bottom of a hill can also have a devastating effect on average speed. Such delays are often a matter of luck and may be fairly frequent on a. particular run, despite relatively light traffic. They will not occur on the motorway.
To obtain a first-hand impression of conditions on the AS route before November 2, during a typical night run, I accompanied the driver of an Atkinson maximum-load six-wheeler operated by Shenstone Transport, Ltd., from the company's Birmingham depot to Royal Victoria docks, London. Following the company's practice, the schedule was based on a maximum speed of 30 m.p.h.
Powered by a Gardner 6LW oil engine, the six-wheeler was equipped with a fivespeed gearbox having an overdrive top gear giving a maximum speed of around 42 m.p.h., and of about 31 m.p.h in direct drive. The ease with which changes could be made from overdrive to direct drive, and the negligible loss of road speed, were of outstanding value when climbing slight gradients.
A start was made at about 11.30 p.m., and the 120-mile trip to the docks was completed in a little under five hours. There were no enforced stops as a result of congestion, and delays that could be debited to obstruction by other vehicles were caused by speed limitation on gradients when following fully laden multi-wheelers. The Atkinson was carrying 10 tons "oelectrical equipment destined fo America, or 2 tons less than its rate( payload. The height of the load wa. some 3 ft. above cab level. The drive said the overall average consumption rah of the vehicle was about 12 m.p.g.
A vehicle of this type could normal!) cruise comfortably at 36-37 m.p.h., anc could average 30-31 m.p.h. . on a nigh run. Driven at its maximum speed when. ever possible, it might average 33 m.p.h This would apply also to maximum-loac eight-wheelers with more powerfu engines.
Night Preferred
Like other drivers with whom I have travelled on night runs, the driver of the Atkinson greatly preferred night to long. distance day work. The absence el pedestrians, dogs, livestock, cyclists, slow. moving delivery vehicles, cars in scaret of parking places and other vulnerable traffic greatly reduced the strain ol driving, he said.
Because I wanted to make the second run as soon as possible after the motor. way was opened, I could not be selective as to the vehicle in which I travelled. In the event it was a fully laden Atkinson maximum-load eight-wheeler operated by Storage and Haulage, Ltd., an associated concern of Shenstone Transport, Ltd. This vehicle was also powered by a Gardner 6LW oil engine, but it, maximum speed was governed to about 31-32 m.p.h.
Its slow speed appeared in prospect to detract from the interest of the run. My disappointment was, however, quickly dispelled when we were travelling on the motorway. After a few miles, it was obvious that a low-speed heavy vehicle had everything to gain and nothing to -lose by running on the motorway.
During the run of 65 miles from the Dunchurch spur to the roundabout at the end of the M10 spur, the driver changed five times from the direct top gear of the four-speed gearbox to third
tar, and at no time were the brakes used. Running time was 2 hours 15 minutes,
■ hich gave an average of 28.9 m.p.h. 'raffle was comparatively light and there tere no delays. In the main, the speed f vehicles that passed us (in both direcons) appeared to be about 42-45 m.p.h. Ve overtook one vehicle, a bulk-load ight-wheeler.
Because of its low governed speed, the wry had a reserve of power for hilllimbing that enabled lesser gradients to e climbed with a negligible reduction in 3 ad speed. The steepest section on the luthward journey has an average radient of 1 in 34 for about 200 yd., nd this reduced the speed in third gear ) 17-18 m.p.h On other up-gradients se speed did not drop below 20 m.p.h., rid I estimate that third gear was used Jr less than three miles out of 65.
The driver had driven vehicles of all ypes on the A5 route during the 20 years
e had been employed by the Shenstone ompany and the run was his first xperience of the motorway, To have riven a similar distance at night on the 1.5 route would, he thought, have ivolved at least 200 gear changes and 'any brake applications, In his view he motorway provided a direct saving of 0-30 minutes, as well as greatly improvig driving conditions and reducing lental strain. " rvfotorway every time "' ?as his preference.
The reserve of hill-climbing power ierived from the low back-axle ratio proided A flexibility at lower speeds that muld have been obtainable at higher peeds if a multi-speed gearbox with suithie ratios had been fitted. The length rf the gradients is such that an increase 1 climbing speed would give an appreiable gain in average speed. Correct gear aatching would also contribute to fuel conorny.
It is pertinent that the overdrive ratio
f the Midland " Red " C5 motorways oach (The Commercial Motor, Novern
her 6) is matched to the final-drive ratio and direct drive to give the best performance.
As the second run' showed, heavier vehicles offer the greatest scope for increased economy by improving the performance. It also indicated the need to employ a road-speed governor, as well as the normal type, if the vehicle is equipped with an engine of higher power for motorway operation.
Mr. J. E. Weatherhogg, managing director of the two haulage companies, has estimated that the motorway will provide an average saving in overall operating time of 10-15 per cent. He endorsed the claim that the predictability of running on the motorway is one of its outstanding merits. He forecast an average saving in journey time for day runs of an hour each way, which, in
the case of some types of traffic, would enable the driver to return to base the same day.
Whereas day runs .of about 110 miles to London formerly occupied upwards of five hours, and particularly heavy congestion on the A5 route added substantially to the running time, the motorway should enable the normal schedule for 40 m.p.h. vehicles to be based on an average of four hours.
It is customary for Shenstone drivers to collect a load in the Birmingham area in time for a night delivery to traders in London, after which the vehicle is driven to the West Ferry Road depot of the company. A local driver collects the back-load and, after resting, the Birmingham driver returns, to his depot with the same vehicle.
If a return run is made on the same day it will not be possible to double the effective output of work because of loading complications, but an increase of half should be possible if the load can be easily handled.
Of the 45 vehicles in the combined fleet, eight to 10 lorries leave the Birmingham district daily for tramping runs to the London area. Atkinson lorries represent the largest number of the same make of heavy vehicle engaged in long-distance work, Traffic is organized in close co-operation with other member concerns of the Transport Development Group, Ltd.
On the debit side of the.motorway, Mr. Weatherhogg expects an increase in the wear of mechanical components and tyres. Higher sustained speeds will, he thinks, necessitate greater engine outputs and transmission ratios accurately matched to gradient requirements, to enable average speed to be increased without raising the total number of engine revolutions. An improvement An braking efficiency is also considered essential, particularly in relation to fade characteristics.
In agreement with the general view, Mr. Weatherhogg regards 50 m.p.h. as the peak economic speed of heavy vehicles on the motorway. This, he believes, should be the statutory maximum for " heavies." Lighter vehicles should, however, be permitted to run at higher speeds.
He is particularly anxious about highspeed coasting downhill by heavy vehicles. During the inaugural run, the Midland " Red " C5 coaches coasted at speeds approaching 80 m.p.h., but they were equipped with unusually efficient disc brakes and with good anti-fade characteristics.
Mr. Weatherhogg is not alone in his apprehension. It is shared by Mr. W. P. James, West Midland Licensing Authority. When, on the Midland." Red" run, I discussed goods-vehicle braking problems with him, he asked, "When are the makers going to improve their braking systems?
A re Mr. Weatherhogg and Mr. James being unduly anxious? Manufacturers and operators might like to reply.
Undoubtedly many operators are concerned about brakes, and other vehicle components the suitability of which for motorway running at sustained high speeds is open to question. Export-type vehicles may be the answer.