30 m.p.h. for "Heavies"
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in Terms of s. d.
ON May 28 "The Commercial Motor" dealt with the influence that a general speed limit of 30 m.p.h. for
heavy goodsvehicles might have on design. This week I am going to deal with the economic aspect of the proposal, so that the law-abiding haulier, whose drivers do not, within his knowledge, exceed the speed limit, may know in pounds, shillings and pence what benefit he is likely to derive from the change.
The less scrupulous operator is probably looking forward to the change as inaugurating a period in which he need not be apprehensive of his drivers' being fined for exceeding 20 m.p.h.
There is also the ease ot the haulier whose drivers find it impracticable on roads in open country to keep their maximum speed below the legal limit. The change will help him, but it will mean that his drivers will not now spend so much time in roadside cafés, time which they find available because they have exceeded their scheduled speeds from one point to another.
In order to obtain some practical information as to the potential saving, it is necessary, first of all, to assess the cost of operation on the basis of the 20 m.p.h. limit and to set beside that .corresponding figures relating to the conditions that will apply when the limit is raised.
A 10-tonner on Three Routes
I propose to take as an example the case of a 10-tonner and will consider it in respect of three routes, say, London to Leicester, 108 miles; London to Leeds. 192 mils; London to Blackburn, 210 miles.
I shall take it for granted, as I may reasonably do, that the vehicle is oil-engined. The first cost may be anything from £1,750 to £2,050, or even more, and I am going to assume a reasonable average, that is, £1.950. Deducting the cost of a set of tyres, £175, I get a net figure of £1,775, and if I assume that the residual value will be £275, that leaves me with a net depreciation figure of £1,500.
It is fair to depreciate the average 10-tonner of British make over six years, which means that for depreciation I mist allow £250 per annum, The rest of my fixed charges will be as follows: For Road Fund tax and licences, £91 10s. per annum; rent and rates, £30; insurance, £85; interest on capital outlay at 3 per cent. per annum, £58 10s.; overheads or establishment costs, £280 per annum. The total, including that item of depreciation, is £795 per annum.
If I spread that over a basic year of 50 weeks of 44 hrs. each, or 2,200 working hrs. per annum, I get, to the nearest penny, 7s. 3d. per hr. That is a basic figure for fixed charges per hour, but does not include wages, which propose to deal with as a separate item.
Now for the running costs. An average figure for m.p.g. on fuel oil is 13, and taking Is. 9d. as the cost per gallon_ that is equivalent to 1.62d. per mile. For lubricants. I shall take 0.23d. per mile and for maintenance 2d. For the tyres. I shall assume an average life of 24.000 miles (although I think in the near future that will be improved upon), which gives me 1.75d. per mile. My total of running costs is thus 5.60d per mile_ The next point to consider is the allowance for loading and unloading, terminal delays, waiting at docks or other loading and unloading places, and so on.
Having decided upon that, we most add an allowance for travelling time, based on the assumption that the legal limit of speed is not exceeded. From these figures a total time for the round journey can be ascertained and the cost assessed on a time basis, plus the above calculated figure of 5.6d. per mile for distance.
Loading time must, as I have already hinted, vary according to the class of traffic, as also must the unloading time, but good average figures for the majority of materials carried on trunk services are as follows: For loading, 10 mins. per ton of payload, plus 15 mins. for turning round, that is, completion of documents, sheeting-up, etc., before the vehicle starts on its journey. As a rtne the unloading time is approximately the same.
As to travelling time, piovision should be made for the fact that at both ends of the journey the vehicle will be travelling through congested traffic, and a fair figure to take is 10 miles at each end. That is 20 miles of journey over which the average speed is most unlikely to exceed 12 m.p.h. For the balance of the jouiney, if the legal limit of 20 m.p.h. be not exceeded, the average speed should not be more than 18 m.p.h., and even that assumes that there are no thickly populated and congested cities or towns to be negotiated in the course of the run.
Now I will apply these principles and figures to the three different routes which I have mentioned. I will take first of all the run from London to Leicester, assuming that to be 108 miles.
The loading time will be 10 times 10 mins., plus 15 mins. for turn-round, which is 115 mins. It will certainly he sufficiently accurate to take 2 hrs. for the loading time and the same for unloading. I do not propose to make any other provision for special delays and will therefore. assume that 4 hrs. is the basic figure to cover loading and unloading and any normal terminal delays.
Average Speed for 108 miles Of our total distance of 108 miles, 20 miles is assumed to be covered at 12 m.p.h.. which takes 1 hr. 40 mins. The remainder of the journey. 88 miles, is covered at an average speed of 18 m.p.h., which is 6 mins, short of 5 hrs. The total time for travelling one way can thus be assessed at approximately 64hrs. Incidentally. that gives an average speed throughout the journey of 16.6 m.p.h. The complete period for the return journey, assuming one-way loading, will thus be 4 hrs. for load handling plus 13 hrs. travelling, or 17 hrs. in all.
1 should mention that for the first series of calculations I am going to assume one-way loading only, thus simplifying the problem in the first stages. I shall subsequently modify the calculations so as to provide for more or less regular return loads.
It is reasonable to assume that, in respect of a journey taking 17 hrs., three complete round trips out and home will be run each week. That would give a net figure of 51 hrs., but in order to make provision for eventualities I propose to take 54 hrs.
The cost can be set out as follows: s. d.
54 hrs. at 7s. 3d. per hr. ,.. 19 11 6 648 miles at 5.6d, per mile ... 15 2 6 Driver's wages, including subsistence and expenses 9 0 0 Total ... ... £43 14 0
In the calculations given it is assumed that no mate is employed and that the driver is on the standard basic rate of £5 15s. per week of 44 hrs., which means that for 54 hrs. he will be paid £7 9s., towhich I have added El Ils. to cover three nights' Subsistence, including 4s. for sundry petty-cash expenditure.
For the sum of £43 14s,, 30 tons have been carried, so that the cost is approximately 29s, I d. per ton.
In the case of the London-to-Leeds journey, it is still reasonable to assume that for 10 miles at each end of the journey the average sliced will be cut down to 12 m.p.h., so that 20 miles of the 192 which is the total will take 1 hr. 40 mins. The remaining 172 miles, at an average speed of 18 m.p.h., will take 9 hrs. 33 mins. The total is thus 11 hrs. 13 mins., and we can quite reasonably take a figure of I lj hrs. for that, or 23 hrs. total travelling time.
The terminal delays are assumed to he the same as before. namely, 4 hrs., so that our total time is 27 hrs. It will thus be possible to accomplish two journeys per week of 54 hrs., and the cost can be set out as follows:— 54 hrs. at 7s. 3d per hr. 19 II 6 768 miles at 5.6d. per mile 17 IS 4 Driver's wages, including subsistence and expenses ... 8 10 0 Total . .. £45 19 10 For the above total of £45 19s. 10d. only 20 tons have been carried, so that the cost per ton is within a fraction of a penny of £2 6s.
The longest journey of the three, from London to Blackburn, is 210 miles approximately. Deducting 20 miles, at 1 hr. 40 mins., we still have 190 miles to run at 18 m.p.h. That will take 10 hrs. 33 mins., so that the total time per journey is 12 hrs. 13 mins., which, as in the last example, we can reasonably approximate to 12s hrs. 1 he total travelling time is thus 25 hrs. Add 4 hrs. for terminals and we get 29 hrs, per journey.
Two Round Journeys a Week
It is still possible to complete two round journeys per week of 58 hrs., in which case the cost will be as follows:— 58 hrs. at 7s. 3d. per hr. ... 21 0 6 840 miles at 5.6d. per mile... 19 12 0 Driver's wages, including subsistence and expenses ... 8 18 0 Total ... £49 10 6 Again the total load carried has been no more than 20 tons, so that the ccst to the nearest penny or so is £2 4s. 6d, per ton.
• Now to consider the modification in times and, of course, cost, which will be brought about when it is legal for this operator to run his 10-tonner at 30 m.p.h. Bear in mind that it is assumed that the operator and his driver do not in any circumstances break the law by driving their vehicles at a fraction of a mile an hour above the legal maximum. In the fist place, it will leadily be conceded that whatever inay be the maximum allowed, there will be no difference in the average speed at which the vehicle will traverse the first and last 10 miles of the journey.
On the Leicester run, therefore, out of a total of 108 miles, 20 miles will take 1 hr. 40 mins., leaving 88 miles which can probably be covered at an average speed of 27 m.p.h., taking 3 hrs. 15 mins. The total time for a one-way journey is thus 4 hrs. 55 mins., and it is quite near enough to take that as 5 hrs. each way. That is to say, the total travelling time will be 10 hrs., to which we must add 4 hrs. for terminals. making a grand total of 14 hrs.
On that basis the vehicle can comfortably complete three round journeys in a 44-hr. week with a little time to spare, and the cost of a week's work is as set out below:— s. d.
44 hrs. at 7s. 3d. per hr. 15 19 0 648 miles at 5.6d, per mile 15 2 0 Driver's wages, including subsistence and expenses . . 7 6 0 Total ... ... £38 70 For that sum of money the tonnage carried is 30 and the approximate cost is 25s. 6d, per ton. This compares with a fraction over 29s, the cost when the vehicle may travel at no more than 20 m.p.h., and shows a saving of round about 12 per cent., which is quite a considerable proportion in !stud cash.
Readers may be interested to compare the average speeds on these two journeys. In the first, with a maximum of 20 m.p.h., the average is 16.6 m.p.h., whereas under the conditions which it is hoped will shortly -prevail with a maximum of 30 m.p.h, the average speed estimated to he possible is 21.6 m.p.h.
A calculation of this kind throws into high relief the importance of terminal times. Here, out of a total of 14 hrs. for a round journey involving a distance of 216 miles, 4 firs.. or nearly 30 per cent., of the total time is occupied in loading and unloading.
If it were possible to cut down the terminal times in proportion to the running times a considerable additional saving in transport costs would result.
London-Leeds in 8 Hours
Now let me deal with the journey to Leeds and back, 192 miles each way, assuming a 30 m.p.h. limit. Making the same assumptions as before, the total travelling time in each direction is 8 hrs equivalent to an average speed of 24 m.p.h. The total travelling time is thus 16 hrs. and the grand total for the journey, including 4 hrs. terminals, is 20 hrs.
It is more than likely that the operator will endeavour each week to complete three round journeys, for which we should allow, say, 62 nrs, If that be accepted the schedule of costs set up in form similar to those given above is as follows:
The tonnage carried is 30 and the cost per ton 40s., comparing with 46s. when the maximum speed is limited to 20 m.p.h. The saving in this case is approximately 13 per cent., which once again is a considerable proportion of any sizeable sum of money.
Finally. I take the third case, the London-and-Blackburn run of 210 miles each way. Calculating the time in the same manner as before, it will he found that 21.1 hrs., say 22 hrs., are necessary for the round journey. It is hardly likely that any atlempt will be made regularly to run three journeys per Neek on this route as it involves a minimum of 66 hrs. per six-day week, which is too long for such a . procedure to be possible.
More Miles; Lower Costs
It cart he taken then that two round journeys per week will be run, taking the a hole 44-hr. week. On that basis the cost would be as follows:— 'fins is almost E2 3x. per ton, as against £2 9s, Sid.. showing a saving of 6s. 6d. per ton, or roughly 15 per cent, with the higher maximum.
In the above examples I have taken one-way loading as involving the least complication and cause for error in assessing times, loadings and speeds. In a subsequent article propose to take the more difficult case and assume that quite frequently return loads are picked up. I will try to show how that alteration in conditions affects the savings, although inevitably, whether there was any return-load wade or not, the economy of being allowed to travel at 30 m.p.h.
instead of 20 m.p.h, would be considerable S.T R.