Report of Committee, Am. Ry. B. and B. Assn. on Fire Protection of Bridges and Trestles. Railway Maintenance Engineer, November, 1919.

Protection of Wooden Bridges from Fire, from report of Amer. Ry. Fire Protection Association. Railway Maintenance Engineer, January, 1920, p. 29.

Report of unusual fire on N. C. & S. L. bridge, p. 335-337; A Fire Wall for Trestle Bridges, p. 332. Railway Maintenance Engineer, September, 1921.

Protection of temporary bridges against fire, from report of Operating Officers Association of the C. & N. W. Ry. Railway Age Gazette, May 19, 1911, p. 1173.

Protection of Wooden Bridges from Fire. Railway Age Gazette, December 15, 1911.

To the American Railway Engineering Association:

Of the seven subjects assigned to it the report of your Committee, submitted herewith for your consideration, covers the following:

(2) Methods for increasing the traffic capacity of a railway. (3) The effect of speed of trains upon the cost of operation. (4) Methods for analyzing costs for the solution of special problems with which this Committee is concerned.

(6) The economical operation of trains against the current of traffic on multiple track railroads.

(7) Begin the study of methods for the determination of proper allowances for maintenance of way expenses due to increased use and increased investment, collaborating with Committee on Records and Accounts.

The Committee has not been able to complete the work assigned to it, with the exception of Subject No. 6. This subject has been very fully covered by the Sub-Committee, with the assistance of the members of the Association. The report is contained in Appendix "D," with definite recommendations.

Considerable study has been given by a Sub-Committee to Subject No. 5, "The feasibility and economy of through routing of solid trains and its effect on the capacity of terminals," but the Sub-Committee is unable to report this year. It is hoped that the result of the investigation of this subject will appear in the report of this Committee for the year 1923.

Reports of Sub-Committees on Subjects 2, 3, 4 and 7 are contained in Appendices "A,” “B” and “C."

Attached as Appendix "E" is a report comparing the operation of one-engine and two-engine trains with three-engine trains, over the west end of the Cumberland Division of the Baltimore & Ohio Railroad.

The result of these tests is of some interest to operating officers having to operate mountain grades with heavy tonnage movements. The report was prepared by Mr. J. E. Teal, member of the Committee, and is published for the information of the Association.

ACTION RECOMMENDED

1. That the conclusions of the Committee given in Appendix D, relating to the economical operation of trains against the current of traffic on multiple track railways, be approved and published in the Manual.

Recommendations for Future Work

The Committee recommends the reassignment of Subjects Nos. 2, 4, 5

and 7.

Respectfully submitted,

THE COMMITTEE ON ECONOMICS OF

RAILWAY OPERATION,

L. S. ROSE, Chairman.

Last year the report of this Sub-Committee dealt in part with a few of the physical elements which more or less determine the capacity of a railroad. The discussion was largely academic and requires results of actual operations to prove its value. For this reason the Sub-Committee undertook to collect data on the physical characteristics of a number of different roads and the traffic which was being handled, for the purpose of noting to what extent the theory was applicable to practical operation. Replies to a questionnaire have been received covering the characteristics and operating data of 23 operating districts. Every case presents an interesting problem, but most of them are so complex that it has not been possible to show the application of the principles to each one.

It has, therefore, been decided to use one or two of the simpler cases which have been worked up to develop the theoretical discussion a step or two farther so that next year wider applications of the theory can be made. That is to say: Next year it is proposed to show the application of these principles to the economic development of a railroad taking into account the growth of traffic through various stages, requiring changes in motive power, additional running tracks, grade revision, signals, etc., and to attempt to show the effects of these changes upon capital expenditures and operating expenses.

NOTES ON THE DETERMINATION OF THE TRAFFIC CAPACITY OF SINGLE AND MULTIPLE TRACK RAILWAYS (SECOND PAPER)

It was pointed out in the discussion last year that traffic capacity refers to the tonnage which can be moved regularly over a given arrangement of tracks in a given time. It depends on track capacity and operating methods. The latter are influenced by ruling grades, size of equipment, character of service, etc.

Track Capacity theoretically is fixed by the arrangement of tracks and passing sidings, and is measured in terms of train-hours per day (or month) per mile of line (or per division). It is based on the assumption that the arrangement of tracks is laid out for perfect operation and that full use is obtained of all passing sidings or other track facilities. In actual operation the arrangement of tracks is not always the best and it cannot be expected that train operations will be perfect, consequently full use will not be obtained from all of the passing sidings and track facilities.

The use which can be obtained in practice from given track facilities depends upon the character of service and no doubt varies with different roads having different methods of operation. It will be difficult to find identical conditions on any two roads, consequently the results obtained from one road may not be applicable to another, but if the actual use obtained from given track facilities or the actual track capacity determined by different railroads is compared with the theoretical track capacity, a useful criterion can no doubt be established which will be valuable in deciding when it will be most economical to provide new facilities.

This year, profiles, track layouts and operating statistics were obtained from a number of different railroads having busy single and double track sections. The Committee has been unable to work up enough of this data to draw final conclusions, but the methods of attack are no doubt instructive, and possibly if some of the roads which are faced with the necessity of installing new track facilities can apply some of the principles discussed to their problems, valuable conclusions can be drawn therefrom.

Determination of Theoretical Track Capacity.

Probably the best way to explain what is meant by the theoretical track capacity of a line is to consider Divisions A, B, C and D, Fig. 1. Divisions A and B are essentially single track lines having 24 and 21 passing sidings between the ends of the double track sections, respectively. There are 25 and 22 stretches of single track between terminals, or one more than the number of passing sidings. (Lap sidings for the present are counted as one.) To obtain the theoretical track capacities of these divisions assume that the sidings are located so that perfect operation is possible, that all trains make the same speed and that full use can be made of all passing tracks. Thus the theoretical track capacities of the single track sections of Divisions A and B are 25 X 24 = 600 and 22 X 24=528 train-hours per day, respectively. (See page 745, Proceedings A.R.E.A., Vol. 22, 1921.) It is also essential to assume that the passing sidings are long enough to accommodate but one train. If it is found by comparing the average length of sidings with the average length of train that the sidings are twice as long as the trains, or if there are lap sidings, then the theoretical track capacity is equal to twice the values found above. That is, it will be possible to accommodate two trains in each siding and thereby be able to operate trains in fleets. This is equivalent to installing passing sidings half the distance apart. (See last year's report.)

Thus, to arrive at the theoretical track capacity of a single track line in train-hours, divide the total length of passing sidings by the length of train it is proposed to operate to obtain the equivalent number of intermediate sidings. Increase this number by one and multiply by 24 to obtain the total train-hours per day for the division.

Divisions C and D include some double track. If the length of double track plus the length of sidings does not exceed 50 per cent of the length of the division it is possible to find the theoretical track capacity