That Tantalizing Ton-mile
Page 44
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FOR once in a while I think I have been too hasty in dealing with an inquiry. A correspondent wrote and asked me to recommend a method of doing something which I have always advised readers not to do. Curiously enough, in putting his request, he referred to an article which I wrote rather more than a couple of years ago and asked that I should provide him with figures similar to those in the article. Actually, the article was written in such a manner as strongly to deprecate any attempt to arrive at a figure for ton-mileage in similar eases, so that it seemed obvious to me that this inquirer had simply seen the figures in a table which accompanied the article and had not read n carefully.
He -raised again the old bugbear of ton-mileage, which has occurred frequently of late, and that fact should have been enough to warn me not to treat this inquirer in so cavalier a fashion.
Only the other day, the transport manager of a C licensee, who was already making up his accounts according to a method of costing which I recommended and was installed year or Iwo ago, came to me again and asked me to add another column for ton-mileage, as he had been asked by his director to give such figures. I told him that the figures were practically impossible to obtain and that when obtained they were of no use, hut he said he had been instructed to produce them.
Useless intornoation His work was to transport machinery all o■rer the country, sometimes full loads, sometimes half loads; at times the vehicles were empty, and at others a Vehicle would run 150 miles with one small machine and come back empty. It was obvious to me, at any rate, that no figure for ton-mileage would be of practical use in a case like that. However, I gave him some help.
Now another operator comes along with a letter of inquiry on the same subject. He says: "I have been asked by my company to furnish the running costs of our transport fleet on a ton-mileage basis, and having retained " The Commercial Motor" of March 24, 1944, in which this costing system relating to a 15-ton machine is described, presume you could supply a costing system applicable to our needs.
"We operate 40-cwt. and 50-cwt. vehicles on delivery work within a radius of 60 miles from the production centre, entailing from 70 to 100 deliveries per day, with the uplifting of empties requiring vehicle capacity similar to the delivered articles.
" One driver and van boy are engaged on each vehicle and approximately one-fifth of the journeys are of two days' duration, thus requiring the driver and attendant to be billeted away from home, "Your guidance and advice would be appreciated on the method to be adopted in calculating the costs on a tonmileage basis."
I replied: "If you will re-read the article which appeared on March 24, 1944, you will find it was designed to make it plain that it is practically impossible to assess ton-mileage rates on vehicles which have a varying load, as yours have. The meaning of the expression " ion-rnile " is load carried at any time in tons, multiplied by the distance that load is carried. In your case the load the vehicle is carrying is constantly varying and you would hava to work the figure out almost mile by mile for every journey for every vehicle, in order to get an accurate result. That process, as pointed out in the article., is so near to impossible that it may be taken to be so.
" Perhaps „you will be good enough to read the article again, and then think over your problem and write to me a second time, when 1 will endeavour to give you some real practical help."
A Faulty Appreciation , Here, again, this is the case of a director asking the transport manager to provide figures in ton-miles. The director obviously does not know the difficulties involved and the transport manager is in a quandary.
Like my other friend, he has to do something in the matter, and I ought, perhaps, to have been a little more helpful. At the same time, it would be impossible to deal with the inquiry in a letter, and I am taking the alternative of writing this article to help him and the many other operators who are in the same quandary. I am convinced that a good deal of this harping on the ton-mileage as a basis of cost arises from test figures for vehicles which give the ton-mileage per gallon. This procedure is probably the best method of comparing the fuelconsumption efficiencies of chassis, but, in such cases, there is no difficulty in calculating the ton-mileage, because the vehicle is fully loaded all the time and the calculation of that ton-mileage is a simple arithmetical calculation. It is when, as in commercial practice, the load varies over each journey, that the calculation becomes complicated, so much so as to be impracticable.
As a matter of fact, the article to which this inquirer refers actually commenced with a reference to some tests made by "The Commercial Motor" with an Albion 15-lonner and the extract from the test figures reads as follows: "Under easy conditions, 240 grosslon-m.p.g„ 164 pay-load ton-rn.p.g,; under hard conditions, 177 gross-ton-mpg., 120 pay-load ton-m.p.g."
One must first understand the difference between grosston-m.p.g. and pay-load ton-m.p.g. To make this clear, I should mention that another figure in the test data elves 10.92 m.p.g. with this vehicle fully loaded under the env conditions. The gross load was 22 tons, and 22 mult:c:ied. by 10.92 gives about 240 gross-ton-m.p.g. The pay-load of 35 tons multiplied by 10.92 gives 164 pay-load ton-m.p.g. The inquirer who inspired that earlier article had a targe