COMPARATIVE ACCELERATION CURVES. Figure 5. This diagram shows the number of seconds required to accelerate a train through a distance equal to the length of 7 cars at various rates of acceleration. As in the braking curves, if the rate is 2 miles per hour per second, it will require 151⁄2 seconds to start from rest and run a distance of 350 feet, whereas if the rate is one mile per hour per second, it will require 22 seconds to run this distance. In actual practice the acceleration is ordinarily accomplished within the limits covered by the shaded area; that is, the trains are accelerated at the rates between I.I and 1.4 miles per hour per second depending on the load, the motormen and the action of the controllers. It will be noticed that the difference between the most rapid acceleration and the slowest acceleration is very small. The only way that the acceleration can be improved to any great extent is to change the gear ratios with the present motors or to add more motors per train. The possibilities in these directions will be discussed under a separate part of the report devoted to the question of motors and speed. THE CAR CAPACITY OF THE SUBWAY. Figure 6. This diagram shows the total number of cars per hour that can be operated over a single track in one direction with various headways and different lengths of trains. The curves show at once the benefits to be expected by decreasing the headway and at the same time increasing the length of the trains. The following points have been located on the diagram |