planning, 1 DD is considered the same for all divisions of the
railway in operation.
To find the number of cars by type for 1 day's dispatch, first
multiply the EDT by the percent of EDT to be hauled in each type of
car. Then divide the result by the carrying capacity (payload) of
the cars. For example:
Therefore, you find that 1 day's dispatch consists of 55 boxcars, 44
gondolas, and 11 flatcars, a total of 110 cars.
When you find the value for 1 day's dispatch, your next step is
to determine how many cars are required to move the EDT every day.
To find this number, multiply 1 DD of each type of car by the
turnaround time, and add a 10 percent reserve. The turnaround time
for this hypothetical railroad, as shown in figure 3.1, is 9 days.
Your calculation should be as follows:
*Whenever you have to add a reserve factor, you can eliminate one
step in your computations by multiplying by the following equivalents