The procedure would be as follows (see example below): Begin by assuming that the conditions of operation for the three sections P-R, R-S and S-V are the same except that the sections are not the same length. Values of to, 1, and T for sections P-R and R-S are then calculated, correcting for the difference in length of sections. The next step is made to correct for the difference in the number of trains operated over each section, and the third step is for the purpose of correcting for the difference in speed of trains over the various sections.

Thus we have given for section S-V M= 30.7 miles, N=135 trains, S=17.68 M.P.H. to 1.736 hrs., n = .7955 and T = 2.85 hrs. For section R-S we have given M31.3 miles, N = 125 trains and S=25.93 M.P.H from which to find to, n, and T corresponding:

This comparison is interesting because it shows that the results obtained by the application of the theoretical laws are approximately the same as obtained in actual operation.

In most cases we look for much greater variations between the theoretical and actual results than shown above, because the procedure thus far only corrects for lengths of divisions, number of trains and train speeds. Other conditions, such as difference in track facilities, characteristics of motive power, supervision, etc., have their effect which we hope can be similarly analyzed and closer comparisons drawn between various methods of operation.

The work assigned to Sub-Committee No. 3 was the study of the effect of speed on the cost of operation.

As was done last year the work was divided into three parts:

1. Effect of speed on the cost of maintenance of way.

2.

Effect of speed on the cost of transportation.

3. Effect of speed on the cost of maintenance of equipment. No new data have been obtained nor do there appear to be any data available that have not been used. Certain tentative conclusions have been drawn from such data as were available and these conclusions are given to the Association that they may be proven or disproven by such experiment or analysis of accounts as the several members may wish, or be able to make. In the absence of disproving evidence, the conclusions are thought to be worthy of acceptance.

TENTATIVE CONCLUSIONS

1. Other conditions remaining unchanged, the cost of maintenance of way increases with increased speed of operation.

Exact relation has not been established nor can it be established alike for all conditions of track, roadbed, and traffic.

For minor differences in cost due to minor changes in speed not requiring changes in maintenance standards it may be assumed, until experiment proves otherwise, that the cost of maintenance of way varies with speed of operation as set forth in the report of this Committee in the Proceedings of 1921 at pages 760 to 772. For convenience the numerical values found in that discussion are repeated below in Table 1. TABLE 1-DIFFERENCES IN COST OF MAINTENANCE OF WAY DUE TO MINOR CHANGES IN SPEED OF OPERATION

NOTE-In this table "C" varies with the several items and in each line of the table is the main line cost of the particular item of its tabular line for any particular road or division at an assumed or the usual average speed; and "V" is any change in speed under consideration in miles per hour. It must be remembered that the table is not good for changes in speed requiring or permitting a change in maintenance standards.

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When cost is not separated into straight line and curved line costs the coefficient of CV is taken as the weighted average, the weights being the percentages of straight and curved line. Thus: If 60 per cent of

the line is straight and 40 per cent is curved we have for passenger trains and ties

(6 X .0011 + 4 X .0150)÷10=.00666 and for freight trains and ties

(6 X .0014+4 X .0180) 10=.00804

2. Cost of transportation will vary materially with variation in speed but it is not possible to determine in general a most economical speed expressed in miles per hour. The effect of variations of speed will depend on the characteristics of the division under consideration, on the wage system, on the character of the traffic, and on commercial considerations.

a. Since varying speed affects the load that can be hauled, the effect of speed cannot be considered apart from the train load. Provided there. are no pusher grades, and that the wage system is a straight hourly pay system, traffic that does not require quick movement is moved most economically in maximum trains, defined to be those that can be handled at minimum practicable speed on the de facto ruling grade of the division. Under these conditions the most economical speed for the maximum train is the fastest speed that can be made safely over the division. If there are pusher grades or if the wage system calls for extra pay for all time over a standard day, then each division must be worked out for itself by experiment or as is outlined in pages 773-791 of the Proceedings of 1921.

b. Subject to the limiting effect of pusher grades and wage system it may be said that with a given weight of train the most economical speed is the fastest that can be made safely over a division.

C. The operating cost is a minimum under conditions “a” and “b” when the resulting speed is the one which permits the locomotive to be operated at the most economical rate of power production.

3. No data have been found that will throw any light on the relation of speed to cost of maintenance of equipment. It is believed that owing chiefly to the effect of impact and braking there will be a slight variation in the cost of maintenance of equipment with variations in speed that are not great enough to require change in character of equipment. When the speed becomes higher than that for which the locomotive is designed the cost is believed to increase rapidly with increase in speed.

The Committee on Economics of Railroad Operation is interested in. a great variety of transportation subjects in which various unit costs play very important parts. As the investigations of the Committee progress, many important problems will no doubt present themselves for economic comparisons, so that we feel that the assignment could not be properly completed until the scope of the Committee's investigations is more clearly outlined.

The Committee has already made some investigations and has others in progress in which the train-mile cost unit is an important consideration in the economic comparisons which are being studied, so that we have undertaken the study of analyzing freight and passenger train-mile costs as influenced by changes in locomotives, grades, operating methods, etc. This investigation is now in progress.

Subject No. 7, "Begin the study of methods for determination of proper allowances for maintenance of way expenses, due to increased use and increased investment, collaborating with the Committee on Records and Accounts."

The studies and discussions to date have covered the field of previous investigations on this subject more or less closely related to rate litigations in various parts of the country. Detailed reference has been made to the more recent developments brought about by the activities of committees working on related phases of the subject for the Railroad Administration and Corporate Associations during and subsequent to Federal Control. It is agreed that some of the facts and conclusions developed in these investigations would be helpful in the study of our assignment, which we consider is intended to cover a broader and more comprehensive view of the maintenance field than that which prompted the investigations referred to.

The selection or development of a suitable transportation unit as a measure of "use" is considered the first step in the study. It was decided that the "use" unit should be related in as definite a way as possible to the two general classes of traffic which are in general distinguished by differences in speed of movement and total gross weight. These two factors in some manner directly influence the necessity for maintenance reparation. The following transportation units, train-mile, engine-mile, net ton-mile, gross ton-mile, car-miles, engine ton-miles and tractive power-mile, were studied and compared with the tentative requirements of the unit and were all rejected because they singly are not sufficiently inclusive to cover the variations in traffic.

It was tentatively concluded that some form of equated transportation units would have to be used to relate and measure the effects of passenger and freight service to maintenance requirements, until such time as maintenance and accounting science should develop a more accurate measure. The availability of the transportation units selected is given consideration. The necessity of having a maintenance “unit” related to a "use" unit was also developed.

The experience of the joint meeting with the Records and Accounts Committee indicated clearly the advisability of having the two SubCommittees act essentially as a single committee in the study of the subject up to the point where appropriate units can be established so that the special function of the Records and Accounts Sub-Committee in developing the accounting and record phases of the subject may become active.