交通规划-交通网络配流.ppt
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User Equilibrium Assignment Network Assignment Transportation Planning User Equilibrium Assignment Network Assignment Transportation Planning User Equilibrium Assignment flows average travel cost total travel cost How about the results if the travel cost of all links is fixed? UE SO Network Assignment Transportation Planning User Equilibrium Assignment flows average travel cost total travel cost How to achieve the total system cost? UE SO Network Assignment Transportation Planning All-or-Nothing Traffic Assignment 1 3 4 5 2 2 7 8 4 1 3 5 6 to 1 2 3 4 5 from 1 0 50 60 70 30 210 2 40 0 30 60 80 210 3 90 40 0 20 50 200 4 80 70 90 0 30 270 5 30 40 50 60 0 180 240 200 230 210 190 1070 1 3 4 5 2 15 7 6 5 8 3 12 5 Network Assignment Transportation Planning 1 3 4 5 2 1 3 4 5 2 Node 1 Node 2 Node 3 Node 4 1 3 4 5 2 1 3 4 5 2 link 1: 1→2; 1→3; 2→1; 3→1 Node 5 1 3 4 5 2 1 3 4 8 1 3 8 6 1 3 7 8 4 6 7 8 4 6 7 8 link 2: link 3: 1→3; 2→3; 3→1; 3→2 link 4: 4→1; 5→1 link 5: link 7: 3→4; 3→5; 4→3; 5→3 link 8: 1→4; 2→5; 3→5; 4→5; 5→4 link 6: 2→4; 2→5; 4→2; 5→2 Transportation Planning All-or-Nothing Traffic Assignment 1 3 4 5 2 0 210 290 110 240 220 0 250 1 3 4 5 2 15 7 6 5 8 3 12 5 Network Assignment Transportation Planning Capacity Constraint Traffic Assignment As traffic volume increases, speed decreases. This process assigns trips according to the impedance function of the links of the network. By considering the direct relationship between travel time and traffic volume, capacity restraint can be incorporated. Capacity restraint attempts to balance the assigned volume, the capacity of a facility, and the related speed. Network Assignment Transportation Planning Capacity Constraint Traffic Assignment Incorporating capacity restraint. The most common method is to load the network and adjust assume link speeds after each loading to reflect volume/ capacity restraints. These loading and adjustments are introduced until a balance is obtained. Experience shows that a balanc
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