mission. Common train operation expense includes the expense of trainmen, enginemen, and train dispatchers and related station expense. The passenger category included assistant conductors and train attendants. Baggagemen expense is self-descriptive. All of these smaller categories of cost were instituted to be available either in the aggregate or, by division of service units, as unit costs apply to the 1-week traffic study.

Running-car expenses were separated by type of car, i. e., head-end, combination passenger, passenger, and motor propelled, with a separate category for car cleaning costs which were considered unrelated to distance in contrast to the other running-car costs. The car expenses are principally car repairs, depreciation, rents, and train supplies and expenses. Each car type group was set up to differentiate between ownership, operation in the case of passenger cars— pullman, and description, such as, coach, passenger compartment, mail apartment, other head-end portion, et cetera. On the whole, there were 20 separate categories of running-car costs each associated with appropriate service units in a computation of unit costs for application to the traffic study. The car cleaning costs were estimated on the basis of a special study in the 1948-49 proceeding which showed 40.68 percent of train supplies and expenses, account 402, as cleaning costs. They were allocated to types of car on the basis of October 1948 ratios of car cleaning expenses, 15 test carriers. Inclusion of crew car-miles with coach car-miles in the proration to type of car resulted in a very small understatement in head-end unit cost per car. Actual passenger-car repairs were allocated to types on the basis of constructive car repairs determined by applying an estimated cost per car-mile by types of cars to the annual car-miles. The unit costs per car-mile were based on a special study data from 5 carriers, 3 of which furnished a separation of motor propelled units. Rent for passenger cars, pullman, express, and privately owned were assigned direct and other rent, railroad-owned cars, was apportioned on the basis of car-miles weighted for standard mileage rate differentials. Any weakness in the assumed equal opportunity of head-end cars and passenger-carrying cars of being rented is immaterial because a not substantially different amount of rent income credit is handled on the same basis. There is, however, an apparent need for more detailed accounting measures in the car repair and rent accounts as to types of Car depreciation by types was, in part, furnished by the carriers. Such data for passenger-carrying cars were assigned to pullman operated, per that company's annual report showing, and an amount to railroad owned other than coach at the same depreciation per car-mile, i. e., 1.746 cents. The remaining coach depreciation was separated between locomotive-propelled and motorpropelled on the basis of car-miles. The head-end and combination car depreciation data were, in part, assigned to passenger compartment on the basis of the depreciation per car-mile of coaches, i. e., 2.485 cents. The remainder was apportioned on the basis of head-end car-miles-railroad owned. Train supplies and expenses other than car cleaning were apportioned on the basis of the special study of October 1948, aforementioned. Except for the group of car cleaning costs by type of car which was related to total cars in and out of terminals for the computation of unit costs, the unit costs were based on annual car-foot-mile statistics as built up from annual car-mile statistics and average car lengths from the test study.

cars.

The terminal costs, other than switching and station, were a minor amount of less than 1 percent of the total costs, and were translated into a unit cost per car in and out of terminals.

The train switching unit cost was determined on the basis of total passengertrain car-foot-miles. Cars not handled by switch engines appear to be a more applicable unit. However, the amount to be considered is insignificant in the light of the overall problem of costing out the traffic study. Yard switching unit costs by types of car were determined from constructive switching-engine minutes, partly on the basis of the April 1955 test week wherefrom were determined the car-mile per car in and out of terminals and the percent of cars handled by switch engines, and partly on the basis of the October 1948 study of switching at 12 terminals. The car-miles in passenger trains for the year 1955 were translated to cars handled by switch engines to which were applied average switch-engine minutes per car to build up total constructive minutes per car by types. The ratios of these minutes were used to apportion most of the yard switching costs except car repairs which represent 5 percent of all the car repairs which had been apportioned to types on the basis of estimated per car-mile costs. If these repairs assigned to switching, i e., the 5 percent of total car repairs, had been apportioned to types of car as were the other switching costs on the basis of switching minutes, only a very small increase in head-end car unit cost would have resulted.

Station employee costs were separated between mail and other on the basis of the special study of station labor made in April 1955. The feet of mail loaded and unloaded in the period were converted to pieces of mail by application of the bin test factor and a mail compensation to employees per piece determined from the mail employee compensation for the test month. Projection to the year 1955 was made by applying the compensation per piece to an estimate of the year's mail loaded and unloaded which result was increased for overheads in this cost category. The percent of this mail cost to the total is 42.17 percent compared to 41.83 percent in the carriers' study. The unit cost was computed per piece of mail handled.

Station-other costs are composed mostly of station and office building maintenance, depreciation, and supplies and expenses, 11 percent of which were assigned to mail on a station use value basis. A unit cost was computed on the basis of pieces of mail handled.

The final step in the Department's cost study is essentially a costing out of the carriers' test week traffic by application of the unit costs determined at both levels of cost, i. e. fully distributed and out-of-pocket, but not without major changes and alterations in the test week data and new and considerably different approaches in mail cost finding technique. Also involved are the Department's measures of railroad mail handling which reflect on the efficiency of the carriers and project less cost into the future than that which was actually incurred as part of the basis for future rates.

The backbone of estimated mail costs, that is, the assignment of train space among the several passenger traffics, reflects the situation in a period which was selected as being representative by the carriers. However, the Department has adjusted these test week data in many ways before applying the predetermined unit costs on the basis of their conclusions that the week was faulty as to representatives, that the carriers had erroneously assigned space in certain instances, and that the space operated was in excess of that necessary for efficient movement of mail.

Whereas, the railroads, on the basis of their test week data, assigned 212,029,000 car-foot-miles of space to mail out of a total of 1,507,179,000, the Department assigns 202,615,000 out of a slightly different summarized total of 1,507,144,000 car-foot-miles, or 9,414,000 car-foot-miles less than the railroads' assignment. By types of traffic, the space assignments are as follows:

mission. Common train operation expense includes the expense of trainmen, enginemen, and train dispatchers and related station expense. The passenger category included assistant conductors and train attendants. Baggagemen expense is self-descriptive. All of these smaller categories of cost were instituted to be available either in the aggregate or, by division of service units, as unit costs apply to the 1-week traffic study.

Running-car expenses were separated by type of car, i. e., head-end, combination passenger, passenger, and motor propelled, with a separate category for car cleaning costs which were considered unrelated to distance in contrast to the other running-car costs. The car expenses are principally car repairs, depreciation, rents, and train supplies and expenses. Each car type group was set up to differentiate between ownership, operation in the case of passenger carspullman, and description, such as, coach, passenger compartment, mail apartment, other head-end portion, et cetera. On the whole, there were 20 separate categories of running-car costs each associated with appropriate service units in a computation of unit costs for application to the traffic study. The car cleaning costs were estimated on the basis of a special study in the 1948-49 proceeding which showed 40.68 percent of train supplies and expenses, account 402, as cleaning costs. They were allocated to types of car on the basis of October 1948 ratios of car cleaning expenses, 15 test carriers. Inclusion of crew car-miles with coach car-miles in the proration to type of car resulted in a very small understatement in head-end unit cost per car. Actual passenger-car repairs were allocated to types on the basis of constructive car repairs determined by applying an estimated cost per car-mile by types of cars to the annual car-miles. The unit costs per car-mile were based on a special study data from 5 carriers, 3 of which furnished a separation of motor propelled units. Rent for passenger cars, pullman, express, and privately owned were assigned direct and other rent, railroad-owned cars, was apportioned on the basis of car-miles weighted for standard mileage rate differentials. Any weakness in the assumed equal opportunity of head-end cars and passenger-carrying cars of being rented is immaterial because a not substantially different amount of rent income credit is handled on the same basis. There is, however, an apparent need for more detailed accounting measures in the car repair and rent accounts as to types of Car depreciation by types was, in part, furnished by the carriers. Such data for passenger-carrying cars were assigned to pullman operated, per that company's annual report showing, and an amount to railroad owned other than coach at the same depreciation per car-mile, i. e., 1.746 cents. The remaining coach depreciation was separated between locomotive-propelled and motorpropelled on the basis of car-miles. The head-end and combination car depreciation data were, in part, assigned to passenger compartment on the basis of the depreciation per car-mile of coaches, i. e., 2.485 cents. The remainder was apportioned on the basis of head-end car-miles-railroad owned. Train supplies and expenses other than car cleaning were apportioned on the basis of the special study of October 1948, aforementioned. Except for the group of car cleaning costs by type of car which was related to total cars in and out of terminals for the computation of unit costs, the unit costs were based on annual car-foot-mile statistics as built up from annual car-mile statistics and average car lengths from the test study.

cars.

The terminal costs, other than switching and station, were a minor amount of less than 1 percent of the total costs, and were translated into a unit cost per car in and out of terminals.

The train switching unit cost was determined on the basis of total passengertrain car-foot-miles. Cars not handled by switch engines appear to be a more applicable unit. However, the amount to be considered is insignificant in the light of the overall problem of costing out the traffic study. Yard switching unit costs by types of car were determined from constructive switching-engine minutes, partly on the basis of the April 1955 test week wherefrom were determined the car-mile per car in and out of terminals and the percent of cars handled by switch engines, and partly on the basis of the October 1948 study of switching at 12 terminals. The car-miles in passenger trains for the year 1955 were translated to cars handled by switch engines to which were applied average switch-engine minutes per car to build up total constructive minutes per car by types. The ratios of these minutes were used to apportion most of the yard switching costs except car repairs which represent 5 percent of all the car repairs which had been apportioned to types on the basis of estimated per car-mile costs. If these repairs assigned to switching, i e., the 5 percent of total car repairs, had been apportioned to types of car as were the other switching costs on the basis of switching minutes, only a very small increase in head-end car unit cost would have resulted.

Station employee costs were separated between mail and other on the basis of the special study of station labor made in April 1955. The feet of mail loaded and unloaded in the period were converted to pieces of mail by application of the bin test factor and a mail compensation to employees per piece determined from the mail employee compensation for the test month. Projection to the year 1955 was made by applying the compensation per piece to an estimate of the year's mail loaded and unloaded which result was increased for overheads in this cost category. The percent of this mail cost to the total is 42.17 percent compared to 41.83 percent in the carriers' study. The unit cost was computed per piece of mail handled.

Station-other costs are composed mostly of station and office building maintenance, depreciation, and supplies and expenses, 11 percent of which were assigned to mail on a station use value basis. A unit cost was computed on the basis of pieces of mail handled.

The final step in the Department's cost study is essentially a costing out of the carriers' test week traffic by application of the unit costs determined at both levels of cost, i. e. fully distributed and out-of-pocket, but not without major changes and alterations in the test week data and new and considerably different approaches in mail cost finding technique. Also involved are the Department's measures of railroad mail handling which reflect on the efficiency of the carriers and project less cost into the future than that which was actually incurred as part of the basis for future rates.

The backbone of estimated mail costs, that is, the assignment of train space among the several passenger traffics, reflects the situation in a period which was selected as being representative by the carriers. However, the Department has adjusted these test week data in many ways before applying the predetermined unit costs on the basis of their conclusions that the week was faulty as to representatives, that the carriers had erroneously assigned space in certain instances, and that the space operated was in excess of that necessary for efficient movement of mail.

Whereas, the railroads, on the basis of their test week data, assigned 212,029,000 car-foot-miles of space to mail out of a total of 1,507,179,000, the Department assigns 202,615,000 out of a slightly different summarized total of 1,507,144,000 car-foot-miles, or 9,414,000 car-foot-miles less than the railroads' assignment. By types of traffic, the space assignments are as follows: