The target year productions and relative attractiveness of the four zone city have been estimated as follows (Table 2). The calibration of the gravity model for this city estimated the parameter c to be 2.0 and all socioeconomic adjustment factors to be unity. Apply gravity model to estimate all target interchanges Tij and to estimate the total target year attractions of each zone given the target year inter-zonal impedances in Table 3.

Table 2 Relative Attractiveness Table 4 Inter-zonal Impedances Productions Attractiveness 1500 1/i 1 |2 | 4 10 15 20 10 10 5 Zone 3 1 1 5 1200 3 2 10 5 15 2600 2 3 15 10 4 4 20 15 10