Referring to the McKeen gasoline-driven car and one of the gasoline-electric type that were introduced in the early part of the present century and were the pioneers among self-propelled cars for railroad use, the author ascribes their limited success to their excessive weight and to engine and transmission troubles. Both these types, he thinks, might have been developed successfully had the gasoline engine been in its present state of efficiency and reliability.
The early attempts having been more or less unsuccessful, the construction of all types was discontinued during the war. More recently the progress in the design and construction of highway motor-trucks has caused them to be adapted to railroad service by applying flanged tires to the rear wheels, pivotal pony-trucks forward and a motorbus body for the carrying of passengers and a limited amount of baggage. These motorbus-type cars weigh approximately 500 lb. per passenger as compared with 1500 lb. in the cars originally used and can be maintained with the same ease and at less expense than can a highway motor-truck. But, although these cars were economical, they were not comfortable to ride in, and they have been superseded by slightly larger cars of light weight equipped with the same automotive-type engine but with two pairs of four-wheel pivotal trucks and swing bolsters. This is the type largely in use at present.
About 3 years ago an investigation of self-propelled cars in this Country and in Europe was made by the American Short Line Railroad Association, 500 questionnaires being sent to members of the Association in this Country and in Canada; and many valuable data were acquired regarding the operation of motor cars on short lines and branch lines under all sorts of conditions. The records show that at present 135 roads are operating 164 motor cars, of which 34 are on trunk lines and 130 on short lines. The approximate mileage is 8000. The number of steam trains that have been replaced is 200. One steam road, 108 miles in length, that showed a deficit of $36,000 per year showed a profit of more than $22,000 during the first year of operation with motor cars. The total investment in serviceable rail motor-cars at present is about $2,500,000; the steam-train investment necessary to provide the same service would be from $8,000,000 to $10,000,000.
It is the author's opinion that eventually all branch lines and short lines will become motorized, the limiting factors at present being the inadequate power developed by the most approved type of motor-truck engine. A lower grade of fuel than gasoline will, no doubt, also be found eventually, which will make available a type of internal-combustion locomotive for handling freight service. Increasing the size of the engine will probably require some change in the form of the transmission, for the limit of the present clutch and transmission system has almost been reached. But this may prove to be an advantage.
Among the other economies accruing to the use of the self-propelled vehicle would be the abolition of such facilities as water-stations, coal-stations, roundhouses and the like. The cost of maintenance of the road-bed would also be reduced.
With the further development of automotive equipment the complete motorization of short-line and branch-line railroads may be expected to turn the present operating deficits into profits.
Tables are appended showing the operating statement of a motor car for 1 year and an analysis of the operating cost during this period.


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