Module 2: Transportation planning

Lecture 8 Trip distribution

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Generalized cost

One of the factors that influences trip distribution is the relative travel cost between two zones. This cost element may be considered in terms of distance, time or money units. It is often convenient to use a measure combining all the main attributes related to the dis-utility of a journey and this is normally referred to as the generalized cost of travel. This can be represented as

$$c_{ij}=a_1t^{v}_{ij}+a_2t^{w}_{ij}+a_3t^{t}_{ij}+a_4t_{nij}+a_5F_{ij}+a_6\phi_j+\delta$$ (1)

where $t^v_{ij}$ is the in-vehicle travel time between $i$ and $j$, $t^w_{ij}$ is the walking time to and from stops, $t^t_{ij}$ is the waiting time at stops, $F_{ij}$ is the fare charged to travel between $i$ and $j$, $\phi_j$ is the parking cost at the destination, and $\delta$ is a parameter representing comfort and convenience, and $a_1$,$a_2$,.... are the weights attached to each element of cost function.