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WHAT TRAILER WORKINC OSTS
Page 98
Page 99
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TRAFFIC characteristics peculiar to the operator, rather than costs alone, may well be the major factor in determining the occasions when trailers-whether articulated or drawbar-are likely to prove practical, as well as economic, propositions.
The use of drawbar trailers could be necessitated by the need for greater platform space or flexibility to meet traffic peaks than is readily available with standard " rigids " operating solo. The benefits of both interchangeability and manceuvrability which articulation contributes to economic working are increasingly accepted. An additional advantage of the " artic." can also result from an initial cost differential favourable to this type of vehicle. This could stem from quantity-produced tractor units being available in the medium-price and weight range, but without a counterpart as standard rigid six-wheelers.
Because of the many variations possible in the combination of tractors (or towing vehicles) and trailers, comparison of relative cost becomes more complex_ Additional costing problems are introduced when operating conditions are such that spare trailers can be used to advantage.
With the reservation that any such comparison of cost must be considered in the light of each user's own traffic requirements, I will analyse the operating costs of 3-ton and 10-ton "attics," followed by 8-ton and 16-ton " rigids," with or without drawbar trailers. These are the types considered by Mr. Harold Elliott in his article on pages 174-177. Standard platform bodies are assumed throughout.
With an unladen weight of 3.1 tons, the annual licence duty on the petrol-engined 3-ton " artic" would be £38 15s., or 15s. 6d. per week. Wages will be reckoned at 18 19s., in accordance with R.H.(64) Grade I scales, and inclusive of appropriate allowances for holidays with pay and insurance contributions. Rent and rates are assessed at 10s. per week. With an annual premium of £24, vehicle insurance willamount to 9s. 7d. per week, whilst interest charged at 3 per cent. on an initial outlay of £1,200 would be 14s. 5d. per week. These five items of standing costs total £11 8s. 6d. per week.
Any estimate of average fuel consumption for this class of vehicle must be especially arbitrary, as conditions of operation can vary so widely. I will assume a figure of 11 m.p.g., increased by 10 per cent. to allow for low-mileage working. Where fuel was purchased in bulk at 3s. 9d. per gallon a fuel cost per mile of 4.50d. would result. Lubricants are reckoned at 0.28d. a mile.
Planning for Profit Peculiarities in Operation of Articulated Vehicles Make Straight Comparison With the Cost of Rigids Difficult : Spare Units Can Affect Aggregate Expense
Residual Value
With a set of tyres costing around £120 for the outfit and an estimated mileage life of 30,000, tyre cost per mile would be 0.96d. Maintenance adds a further 2.40d. per mile. After allowing for the cost of the original set of tyres and the ultimate residual value, the balance to be written off will amount to around £950. Assuming a mileage life of 125,000, depreciation cost per mite would be 1.82d., but to allow for low-mileage working I will increase it to 2d. The total running cost per mile is I0.14d. At an average of 200 miles per week, the total operating cost per week would be £19 18s., or 23.85d. per mile.
Having an unladen weight of 4 tons 13 cwt., the 10-ton "attic?' oiler will carry an annual licence duty of £65, or £l 6s. per week. Wages will become £9 6s. 3d. per week, again in accordance with R.H.(64). Rent and rates will also be slightly higher at I3s. per week, relative to the increased a24 overall dimensions of the outfit. As a result of both the higher initial cost and greater carrying capacity, insurance will be reckoned at £68 a year, or £1 7s_ 2d. per week. With a total cost for this particular outfit of £3,170, interest at 3 per cent. on the outlay will amount to £1 17s. Ild. The total for the five items of standing cost is thus £14 10s. 4d.
With this type of vehicle it will, of course, be reasonable to assume a much higher average weekly mileage-say, 800. With a consumption rate of 12 m.p.g., and a bulk price per
gallon of 3s. 10d., fuel cost per mile would be 3.83d. Lubricants are reckoned at a further 0.27d. With an estimated mileage life per set of 30,000, tyre cost per mile is reckoned at 2.38d. and maintenance adds a further 1.99d.
After allowing for the cost of the original set of tyres and the estimated residual value, depreciation is calculated at 3.25d. per mile. Total running cost is, therefore, 11.72d. per mile. Added to the standing cost, this gives a total operating cost per mile of 16.07d., or £53 I Is. for an 800-mile week.
Wider Range
Following the amendment of the Motor Veh:cles (Construction and Use) Regulations to permit the operation of four-wheeled vehicles with a gross laden weight of 14 tons, there is now a wider range of this class of vehicle suitable for drawbar-trailer work. The example I have chosen permits a load of 8 tons when operated solo and has an initial cost of £3,030. With an unladen weight of 4i-4f tons, the annual licence duty will be £60, or El 4s. per week. Wages, while the vehicle is operating solo, again amount to £9 6s. 3. per week. Rent and rates are reckoned at I Is. and insurance slightly less, on account of the lower carrying capacity, at £1 Os. 4d. per week. Interest on the original outlay would amount to £1 I2s., making a total weekly standing cost of £13 13s. 7d.
Assuming the same average weekly mileage of 800, fuel cost per mile will be assessed at 3.54d.. based on a consumption rate of 13 m.p.g. Lubricants will add 0.26d. per mile. With a set of tyres costing around £250 and giving a life of 30,000 miles, tyre cost per mile will amount to 2d. Maintenance is assessed at 2.28d. per mile.
Using the same formula as before, the balance of the initial :e remaining to be depreciated will be £2,430, with a resulting reciation cost per mile of 3.90d. Total running cost per e thus becomes 11.98d. With an average weekly mileage of , total operating cost per mile for this four-wheeled oiler ild be 16.08d., making the total cost for the week £53 12s.
be largest of the four vehicles under consideration—the on eight-wheeler—is assumed to have an unladen weight 71 tons and an annual licence duty of £120, or 12 8s. per k. Incidentally, as with all previous calculations of standcosts, a 50-week year is assumed, to allow for two nonmue-earning weeks when the vehicle may be off the road major overhaul.
/ages will amount to £9 19s, 104.1., being in the category 15-18 tons carrying capacity. Rent and rates are assessed I3s. per week, whilst vehicle insurance costs £2 4s. •a week. h an initial price of around £4,890, the interest charge mnts to £2 18s. 8d., making the total for the five items of ding costs £18 3s. 6d, ,ssuming the weekly mileage is again 800 and the rate of consumption averages 9 m.p.g.. the cost per mile for this a will be 5.11d. Lubricants are assessed at 0.28d. and tyres 5_I2d. per mile. Maintenance is reckoned at 2.38d. and reciation (based on a vehicle life of 250,000 miles) at Fd. per mile. Total running costs per mile are, therefore, 16d.,_ which, when added to the standing cost, gives a total rating cost per mile of 22.33d. The total operating cost an 800-mile week is £74 9s.
Additional Outlay will assume that a similar type of drawbar trailer is used ind both the fourand eight-wheeler. The additional ace duty payable for drawing a trailer varies in accorda with the unladen weight of the prime mover. Up to tons the annual duty is £110 and over that weight and to 4 tons, £15. Where the unladen weight exceeds 4 tons, annual duty payable is £20, which applies to both the mples given here. The additional weekly cost of licence v• for the trailer would, therefore, be 8s.
a accordance with Section 17 of the Road Traffic Act, 1930, late must be carried in both cases, as the unladen weight the trailer exceeds a ton. The basic wage for a 44-hour k for an adult mate as prescribed by 17,11.(64) is £7 I8s. a addition to making allowances for insurance contributions holidays with pay, this amount will have to be increased m estimating trailer costs because of the higher category stage rate to which the driver will be entitled when drawing ailer. The total figure for wages to be debited to the trailer be assessed at £9 4s., whilst rent and rates are reckoned s. 6d. Insurance is calculated at 4s. 4d. and interest at 10d. per week. Total standing costs for the drawbar ler are £10 16s. 8d.
).tel cost per mile is assessed on the basis of the difference he rates of consumption as between the vehicle operating ) and when it is drawing a trailer, and is reckoned in this ance to be 1.28d. Lubricants are nominally assessed at id. per mile, whilst tyres are estimated to cost 1,36d. intenance is calculated at 0.53d. per mile and depreciation 1.64d., making the total running cost per mile 3.94d. Total rating cost per mile is thus 7.19d.. and the cost per week 18s. Total operating costs when running 800 miles per week are 8-tonner solo, £53 12s.; with trailer (total 16 tons), 177 10s. 16-tonner solo, £74 9s.; with trailer (total 24 tons), £98 7s.
As stated earlier, the traffic characteristics peculiar tc individual operators may well have a major effect on trailei policy. Direct comparison of costs as given here would therefore, not necessarily be valid in any particular instance It will, however, be noted that a few weeks of seasonal slackness per year (when only the four-wheeler operating sole might be needed) could well cancel out the difference in cosi as between the rigid eight-wheeler and the four-wheeler with drawbar trailer. Alternatively, the additional £3 Is. per week could provide approximately 25 per cent. to 331 per cent. more platform space.
Triangular Runs In addition to the advantage of flexibility to deal with seasonal fluctuations, another opportunity for the economic use of the drawbar trailer occurs, for example, in triangular runs where the additional carrying capacity is required on only one section. Such opportunities may well increase as the result of the tendency towards industrial grouping. Thus, a reader recently cited an instance in which an 8-ton load was regularly carried 150 miles from A to B, followed by a 14-ton load from B to C and return, a matter of 60 miles, after which the solo vehicle was returned to base at A.
A query sometimes raised by readers regarding the costing of trailer operation concerns the use of additional semi-trailers. Running briefly through the 10 items of operating costs, licence duty is not, of course, payable on extra semi-trailers, nor are additional wages incurred. In most cases g,arage accommodation would probably not be provided for spare semi-trailers, but I will assume, in this instance, a nominal amount of 5s. per week. Similarly, insurance may provide only restricted cover, such as fire and theft, and will be assessed at 2s. per week. Where the initial cost was £800, interest per week would amount to 9s. 7d., giving a total of 16s. 7d. for these three items of standing costs.
Equate Mileage
Where two or more semi-trailers are operated with one tractor unit the total mileage of all semi-trailers should equate to that of the tractor. If, therefore, all five items of running cost are charged to the first semi-trailer, as would be the case if no spares were operated, the only remaining items of running costs to be charged to each spare semi-trailer would be depreciation and, possibly, some maintenance.
If the expected trailer life were 250,000 miles and the sum to be written off amounted to £500, the depreciation cost per mile would be 0.48d. Although, theoretically, the full maintenance cost relative to the total mileage of all semi-trailers may have been charged to the first, a small addition, appropriate to individual circumstances, should be made for each additional semi-trailer. This extra cost will be occasioned, irrespective of mileage, by coupling and uncoupling, for example. Alternatively, particularly where covered accommodation is not available, maintenance may have to be undertaken to prevent deterioration during periods of non-use. These could be long if the operator were engaged on seasonal work S. R.