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When Not To Use Large Vehicles

The Second of Two Articles Dealing with the Problem of Solving the Vehicle Choice for Particular Traffics, Brick Haulage being Problems of IN this, the second of two articles treating mainly with the subject of brick haulage, I am dealing, primarily, with a problem which often besets the owner of a mixed &et. Many operators have a nucleus of 5-6-tonners, with

other vehicles of larger size. One such operator recently asked me to advise, him as to the rates to charge for the carrying of materials which took rather a long time to load, and had to be conveyed over all distances from three mile leads upwards. In the course of examining and soiving that problem, it became apparent that, whereas the

smallest vehicles were suitable for the shortest and up to medium-distance hauls, the large vehicles were uneconomical for employment on short distances.,

The reason is not diffidult to find. When long periods are needed for loading and unloading, the chances are that a large vehicle will be so tied up at terminals that it will rarely be able to complete more than one or two journeys, being unemployed for some two hours, or even more, each day. That condition indicates its unsuitability.

Furthermore, there is the fact that the fixed charges to be borne by ultra-large vehicles—standing charges, plus establishment costs—are greater, in proportion to load capa city in the case of large vehicles, than they are for the notsq-large machines. Unless a fair proportion of the day's work be profit-earning mileage, any vehicle becomes uneconomical in use for such traffics. Hence the disadvantage of large vehicles.

The particular example I had in mind was referred to in last week's article; a 10-tonner would need 6 hours for

the round journey 'involved in a lead of fiire miles. Without facilities for loading up at night, that would mean a minimum loss of the use of that vehicle of l hours per day —a serious matter in a machine of that size and corresponding cost. •

Matters that are interlinked

, While iurning the problem over in my mind, with a view In dealing with it at some time in the near future, I received several inquiries concerning 'rates for brick haulage, a traffic which, as is obvious, is going to be a prominent one fur some years to come. I decided, therefore, to kill two birds with one stone, for brick haulage is the kind of traffic in connection with which this problem of choice of the most

suitable vehicle is frequently liable to arise. • Furthermore, in order to fit the treatment of this traffic

to the other problem,.! decided to deal with it on, the basis of one-way loading and to calculate the rates, not on a direct time and mileage plus weightage basis, as is usual in dealing with such traffics, but according to the number of journeys practicable per day for varying leads.

Another condition is that two men are to be employed on each vehicle, and the assumption is made that they do not receive help either in loading or unloading. The times assumed for these operations are as follow :—With a 5-6tonner, carrying 2,500 bricks, 'a total of two hours; for a 7-8-tonner carrying 3,500 bricks, three hours; in the case ,of a 12-tonner, carrying 5,500 bricks, from four to five hOurs; and for a 14-15-tonner, carrying 6,500 bricks, seven hours.

Some time and mileage figures are necessary so as to be able to make the calculations, notwithstanding the fact that we are taking the number of journeys per day as our basis. These figures are calculated for the various sizes of vehicle and set out in Table I, which was published in the previous article and is reproduced herewith., In that article I dealt mi full with the calculations for times, rates, number of journeys per day, etc., for the 5-6-tonner and the 7-8-tonner,

I now propose to deal with the large sizes of vehicle in similar detail. Taking, first of all, the 12-ton six-wheeled oil-engined machine. This must earn, according to the figures in Table I, £27 4s. per week and Is. Id. per mile run.

Considering, first, the minimum lead of three miles; I take that as the minimum, because, in my opinion, the charge for leads of any distance up to three miles should be the same. The distance covered, it is true, is less, but the time is likely to be as long, and, in some extreme cases, longer, owing, to the fact that the men are more heavily engaged, in loading and unloading over these extremely short leads than they are as the distances increase, For this reason they are thus liable to be more fatigued and to eork slower, The time for the total round Journey, allowing approximately half an hour for travel, is four to five hours loading and unloading, plus half an hour travelling, say five hours. It will, therefore, not be safe to assume that more than two journeys can be completed in a 10-hour day. That means that in a week, allowing for one journey on Saturday morning, there will be 11 round journeys, the number of bricks: carried will be 60,500, the mileage 66, and the total number of hours worked per. week 56.

Assessing the Cost Now, to assess the cost. First of all we have the 427 4s. per week, taken from Table I. In addition, we have to provide for eight hours of overtime at 5s. 8d, per hour. which is 42 5s. 4d. (See Table I.) Then there is 66 miles to be paid for at Is. ld. per mile-43 lls. 6d. The total is 233 Os. 10d., and that, for 60,500 bricks, is lls. per 1,000 (All rates calculated in round figures.) For a five-mile lead we can take the total time of a round journey as averaging 5i hours, which means that we can get two round journeys in pet 11-hour day, again 11 complete journeys, but needing a 60-hour week. The total of bricks carried will, again, be 60,500 and the mileage 110.

Proceeding to assess the cost in the same way as in the previous example, we have 227 4s. per week and 42 5s. 4d. for overtime up to 56 houis Then there is overtime at time-and-a-half for four hours, ,and that, for two men, plus profit, is approximately at the rate of 6s. 9d, per hour, giving us a total of 21 7s. For the mileage, 110 at Is. Id. gives us £5 19s. 2d. The total is thus 436 ISs. 6d., which is equivalent to 12s, 2d. per 1.000 bricks.

For a seven-mile lead tire round journey will take approximately six hours,. so that over this distance we are prac

tically limited to one-and-a-half journeys per day -Of nine to nine-and-a-half hours, oreight per week of 54 hours. The number of bricks •carVien will be 44,000 and the total mileage 112. .The total cost will be £27 45. per week, plus, 21 148, for overtime, to which we must add 112 miles, at Is. lii. The total is 234 19s. 4d., which is equivalent to approximatlly 16s per mile.

For a 10-mile lead one-and-a-half journeys will just be possible per day of 11 hours-that is, eight journeys in a 60-hour week-and, working the details out as•just mentioned, we get 17s. 6d. per 1,000.

Probably the longest journey which can be completed in a day with this 12-ton six-wheeler will involve a lead a 48 miles. Allowing 10 hours per day for this and six days per week, it means that there will be six journeys in the week, carrying a total of 33,000 bricks in 60 hours and covering 576 miles. To assess the cost., we have, first of --6s. 9d.-which is £1 75,; 576 miles 50

at ls. Id. per mile is £31 4s, The total is 262 Os. 4d., which is equivalent to a rate of, roughly, 39s. per 1,000.

Now for the 14-15-ton eight-wheeled so oil-engined vehicle. The basic data for our calculations in connection with this vehicle are :-Weekly time-charge, £30 lie.; mileage charge, Is. 20. per .

mite; overtime, at time-and-a:quarter, 5s. 8d. per hour; at time-and-a-half, fis. 9d. per hour. Bricks carried per load, 6,500; loading and Unloading times, 31 hours each.

It is immediately clear that the shortest lead we have yet . considered-three' milesis, even with rushing, the most that can be done inside the limit of one-and-a-half journeys per day.

Let us work it out. Three-and-a-half hours to load; a quarter of an hour for getting aWay, travelling the three miles and getting into position for unloading and stacking the bricks, That operation takes a further three-and-a-half hours, so that with the quarter of an hour to return, the total per round trip is .71. hours. There is thus only 31 lidurS left of the 11-hour day-just time to reload. The next morning four hours will be needed to deliver the load, unload the vehicle, and return, leaving only ,seven hours for -the third journey, whereas I have shown that seven-end-a-half hours are needed.

For the sake of argninent, let usassume that, with a -little extra speed in loaqing and unloading, one-andea-half journeys are completed each day from Monday to Friday, inclusive, and the final ehallejomney,e completed. ,telt Saturday morning.

That being so, eight loads are delivered each week of 40

50 1

1:,-

5

approximately 60 hours. The mileage run' is 48 only and the bricks delivered total 52,000 Using the basic figures, the appropriate rate can ne

assessed. There is, first of all, the time charge for the week-230 1 l's. Add 22 Sc. 4d, for eight hours of overt ime at 5s. 8d., then El 7s. for four hours at.6s. 9d., and, finally, 22 13s, for 48 miles at Is. 21.d per mile: The total is 237 Is. 4d., and, for 52,000 bricks. that involves a rate of 14s. 3d. per 1,000.

When the lead mileage exceeds three, it will be practicable only to complete one round journey in seven-and-threequarter hours, so that the possible week's total is six loads in six days-a 48-hour week (excluding the overtime payable for working on Saturday afternoon). The bricks delivered will total 39,000 and the mileage, for a five-mile lead, 60. The cost will be £30 Ils, for the week, plus £3 125. 6d. for the 60 Miles at is. 2id. per mile-£34 3s. Oil. in all, or 17s. 6d. per 1,000. If provision he niade for overtime payment for Saturday, the total rises to 235 and the rate per 1,000 bricks is increased by 4d. to 17s. 10d, It is praCticable; on the aforementioned basis, to increase the lead mileage to seven, or even eight, without going outside the limit of eight hours per day. In such circumstances, all that need be considered, in the way of extra costing, is the mileage charge for the additional distance run, For each addition of one mile to 'the lead distance the extra mileage per

• week is 12, and the extra eliarge must be I4s. 6d., 'which is equivalent to an additional 3d. per 1,0110.

For a 12-mile lead eight-and-a-half hours per day will be requisite. The rate will be made up of the time rate

for the week-230 us., four hour' overtime-21 2s. 8d., and 194 miles at is. W., which is £8 14s. The total is ,£40 7s. 8d., or 21 Os. 9d. per 1,000.

And so on, up to the maximum distance practicable in a '10-hour day, which approximates to a 25-mile lead, The rate for that, calculated as in the foregoing examples, should be El 17s. Per 1,000.

To make the story complete, it is necessary to work out a couple of examples involving both the 12-tonner and the 14-15-tonner, assuming a lead distance for each which -w41 occupy two-daysand to assess the rates for such work.

Fit-it, take the 12-totiner. The maximum distance is that which can be run in 15 home, (The balance of 20 hours when the loading and unloading time of five hours

has been subtracted.) That can be taken as 240 miles,

In a week, three such joutneys will he run, delivering 16,500 bricks, The cost will comprise £27 4s, for the basic week, £3 12s, 4d. for overtime, 22 14s. for subsistence, and, for the mileage (720 per week), eas. The total is .£72 les. 4a., equivalent to a rate of £4 10s, per 1,000,

In view of that seemingly excessive fate, it may be adVisable to remind operators that for the sake of this particular argument,.I am considering Only ode-way traffic., which is

admitteAy uneconomic. over such distances. '

In the case of the 14-15-tanner, as the loading and unloading time is seven hours, there are only 13 hours left for travelling. Law-abiding drivers—and operators—will be able to run only 210 miles or so in the time, equivalent to a 105-mile lead. The bricks carried will total 19,500; and the cost will be :674 18s. 7d. The rate must, therefore, be R3 17s, per 1,000.

The rates which have been calculated in this and the previous article are set out, together with others not described, in Table II. By careful examination of the figures in that Table, the haulier can determine, for himself, the solution of the problem which was one of the two subjects of this article.

In the belief that most people are like myself: and can understand a diagram better than a schedule of figures. I have drawn out the graph which,accompanies this article. It is based on the ,figures in Table H. It makes clear the following conclutions :—First, that tile 5-6-tonner is the most economical machine for all lead distances up to and including 50 miles. Secondly, that the 7-8-tonner is the least economical of the four types discussed, coming down only once to the level of the 5-6-tonner, and that at the 70-mile lead. This may he termed the optimum distance for that vehicle, being that at which it runs the maximum profit-earning miles per week. Thirdly, that for leads in excess of 70 miles the heavier vehicles show to advantage, the 12-tonner being best up to 95 miles or so, after which it gives way to the 14-15-tanner.

The crux of the whole problem is, of course, speed. In all these calculations I have assumed that the legal limit is not exceeded, or rarely. It is its 30 m.p.h. which gives t.:-=e 5-6-tonner the advantage which it loses only at 50-mile leads or over, when the superior load capacity of the 12tonner and 14-15-tnriner begins to have effect. The 7-8-boner shows tip, such disadvantage because it cannot carry so much more weight as to overcome its handicap of being limited to 20 m.p.h.

Over the short leads, up to 20 miles, this advantage of speed does not show up so much, because the distances are so short that average speeds are not greatly affected. It is then that the difference in loading time reacts against the larger vehicles.

Naturally, a very different picture could be drawn if, as should be, the speed limit were 30 m.p.h. for all goo is vehicles.

Even at 20 m.p.h., the largest machines can be made more economical if help be available for loading and unloading Where that is provided, at brickyards. and building sites, the 12-ton and I4-15-ton -vehicles are the best for this work over almost all lead distances. As a matter of fact, of course, those conditions usually prevail where such vehicles are employed. S.T.R.