where the [x] operation gives the smallest integer no less than x . The variable h
l v is the average speed
of truck of type h when loaded, h
e v is the average speed of truck of type h when empty and Nh is the
calculated optimal number for trucks of type h .
Results of the above formula can be used in two ways. One is to use the above formula after the
dispatching problem is solved ( h
ij x and h
ij y determined). The other is to use the above formula as another
objective function in the problem formulated in the preceding section and solve the new problem as a
whole. In this study, the formula (11) is used directly after the dispatching problem is solved to calculate
the optimal truck number.