How to Calculate Ton-mile Costs
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• An Enormous Amount of. Clerical Labour is Required in Assessing Ton mile Figures with Accuracy, but Even Then Their Value to an Operator is Practically Nothing
/ . N my previous article I tried to demonstrate the useless
ness of the ton-mile in any estimate of the cost of haulage . operations by referring to a number of practical examples. I showed that in only one case was there any need to consider the ton-mile. This week I shall indicate not only how much it lacks value but also how difficult
it is to calculate: .
The meaning of " tonrmile " is load carried at any time multiplied by the distance involved. A load of 10 tons carried 200 miles is thus described as 2,000 ton-miles. Five tons carried 400 miles is also 2,000 ton-miles.
In the:first instance, assuming that the load is carried in -a 10-ton lorry which costs 18d. per mile to run, the total.egst of the job-is 3,600d., and the cost per ton 360d. The cost -per ton-mile is 1.8d., found by dividing the total .cost by.the,nuMber of ton-miles. In the second case, assuming that a 5-tonnef is _employed and that running costs amount to ls, per .mile, the cost of a 400-mile journey is 400s.The cost per ion-mile is 400s. divided by 2,000, which • is .2.4d: .
, . All that is simple, but on the face of it the assuMOori is. that these two vehicles have travelled the distances fullY laden,. as was the ease jn. the example I dealt with hist week, A vehicle carried cylinders of compressed gas to customers and, returned with empties which weighed as much as the outgoing loads.. That, of course, is exceptional. _ Let us suppose. that the vehicle, a 10-tonner, whilst actually travelling 200 miles, carries a full load on an outward
journey of 100 miles and returns empty. In these circumstances, the ton-mileage would be not 2,000 but only 1,000. The total cosi of the trip would be 2,000 times 18d., 3,6000., and the cost per Ion-mile 3.6d.
• I should make it clear that the factor with which I am at present concerned is payload ton-mileage. There are other ways of regarding the ton-mile; one of them is valuable as a ,Oneans for comparing the performances of different types of vehicle, taking fuel consumption into consideration.
In these instances, however, the gross ton-mile used is not the payload ton-mile. It is the distance run multiplied by the 'gross weight of the vehicle, that is, the weight of the chassis, the load and the driver.
There was an example of the use of this factor Ofi page 139 of The Commercial Motor dated September 3, Figures were given relating to-the Guy Goliath six-wheeler carrying a payload of 13 tons I cwt. 1 qr. Fuel consumption figures were given as 9.3 m.p.g. at an average speed of 22.6 m.p.h. over a 100-mile route and under normal conditions.
The gross weight of the vehicle was 19 tons 17 cwt. 2 qr. T.he ton-mileage was thus 100 times the gross weight, or 1,937.5. FueFconstimption was at the rate of 177.5 gross ton m.p.g.; and .-this is a figure which can be used wheR
comparing • the • performances of other . vehicles. . —
Another figure, perhaps even niece useful to. the technical student, is -the Wile-load-mileage factor. This takes into consideration the speed at which the vehicle was travelling When the other records were nizrde. The fuel-consuniPtion rate of-any vehicle is, of course, affected by. the. speed,. and irt the case of the Guy, the factor was quoted at 4,010.
Let us turn to a typical example of everyday haulage, as put to me in a letter from a correspondent. We will take an operator who works mainly for one customer and runs a fleet of lorries all over the country, sometimes they run journeys full, sometimes half empty. It is obvious that it would be extremely difficult to work out the costs on a ton-mileage basis for a fleet so engaged. and I was able to convince my inquirer that this was so.
Another reader wrote to me and said that he operated 2-ton and 2k-ton vehicles on delivery work within a 60mile radius of a factory. From 70-100 deliveries were involved each day, with
the carriage of empties requiring vehicle capacity similar to that of the outgoing consignments. A driver and a boy were engaged on each vehicle, and about 20 per cent, of the journeys were of two days' duration, thus requiring the driver and companion to be billeted away from home.
He wanted guidance as to a method to be adopted in calculating the cost per ton-mile. I replied that it was practically impossible to assess ton-mileage rates for vehicles which carried varying loads. I advised him that it would be necessary for him to work out the figures mile by mile for every journey to get a result which would, in any case, be only approximately correct.
I realized that this was an instance where a director had asked his transport manager to provide figures for tonmileage purposes—a frequent occurrence. The director obviously did not know the difficulties involved, and the transport manager, knowing the facts, was greatly embarrassed. He had to do something and hoped that I would be able to help him out of a jam.
am convinced that much of this harping on the ton-mile arises from the test figures for vehicles which give the ton-mileage per gallon, as I have already quoted. Here is another example. An inquirer operated a large fleet of 15-tonners, about 60 of them, I believe.
Details of Journey He gave me details of a typical journey. A 15-tonner set out from A for B, unladen. At B, it picked up a 15-ton load for C, where it dropped 10 tons and proceeded to D, where the remainder of the load was taken off. A further 12-tons were picked up in D and ran to London, dropping 10 tons at one point, and running a further 10 miles with the balance of 2. tons.
The lorry returned empty over those 10 miles and picked up another 15 tons, 12 tons for E and 3 tons for F. it ran empty from F to G, and picked up 8 tons from G to H, returning empty from H to the starting point, A.
This information is .summarized in Table I, where the operating cost is shown to be Is. 8d. per mile. The first column describes the journey, the second the load' and the third the mileage from point to point. By multiplying the figures in the third column by those in the second, the ton-mileage for each particular stretch of the journey is obtained. The result is set down ini-the fourth column.
Multiplication of the mileage by Is. 8d. gives us the cost for each stretch of the journey and is entered in the fifth column. Dividing the cost by the ton-mileage figures we get the cost per ton-mile, as shown in the last column. We can use the total figures at the bottom of the table, dividing the total ton-mileage of 6.200 into the total cost, £46 8s. lid., obtaining an average figure of 1.8d. per ton-mile.
Too Much Clerical Labour
This is satisfactory so long as we are concerned with only one vehicle and one week's work, but if we are dealing with a fleet of 60 lorries and have to make such calculations in respect of every one, obviously the amount of clerical tabour involved is enormous. This would not matter if any useful purpose could be served. I like to have a number of figures to look at when I am dealing with haulage problems, but I cannot see anything useful which might be gained in such a case.
However, if responsible company directors are concerned to secure these figures and are prepared to face the cost and complication involved in ascertaining them—so be it.
There are many pitfalls, too, in the way of those who seek ton-mileage data. There are several ways in which the figures, as set out in the accompanying table, can be, and frequently are, applied to obtain what are supposed to be costs per ton-mile, but are really nothing of the sort.
Here is one method which is often used, believe it or not. The tonnage figures in the second column are added and multiplied by the mileage, 560, giving an assumed and erroneous figure for ton-miles of 33,600. Cost per ton-mile would then seem to be 0.3d., whereas it is actually 1.8d.
Furthermore, some operators, in an attempt to approach the truth, will average the load carried, making it 8.6 tons, and multiply that figure by the total mileage, thus arriving at 4,816 ton-miles. The cost becomes slightly less than 3d. per ton-mile, which is quite wrong.
Another way is to include empty journeys in the calculation of the average, thus obtaining, in this instance, an average of tons. The ton-mileage works out to 3,080, a cost per ton-mile of approximately 31d. All the results are different; none of them means anything. I think I have made my point. S.T.R.