Table 129 shows the procedure of incremental assignment for the example network (Example network for PrT assignment procedures). The 2,000 car trips are assigned in three iteration steps (50 %, 25 %, 25 %).
- Iteration step 1
The shortest route, in the unloaded network, is route 2 with an impedance of 18:00 min. It is loaded with 50 % of the car trips, i.e. 1,000 car trips.
- Iteration step 2
The shortest route in the unloaded network is route 1 with an impedance of 20:50 min. It is loaded with 25 % of car trips, that is, with 500 car trips.
- Iteration step 3
After the second iteration step, route 1 remains the shortest route with an impedance of 29:50 min. It is again loaded with 25 % of the car trips, i.e. with another 500 car trips. It now has a total of 1,000 car trips.
- After the third iteration step, route 3 turns out to have the lowest impedance. This route, however, is no longer found because all trips have been assigned.
In the example above, the impedance of a route results from the sum of the link impedances of the route. Additional impedances for connectors and turns are not considered. In addition to this, it is assumed that impedance results from current travel time tCur, and that current travel time in turn results from the BPR function with a=1, b=2 and c=1.
|
LinkNo |
Type |
Length [m] |
v0 [km/h] |
Capacity |
t0 [min] |
|
1 |
20 |
5000 |
100 |
1200 |
03:00 |
|
2 |
20 |
5000 |
100 |
1200 |
03:00 |
|
3 |
20 |
5000 |
100 |
1200 |
03:00 |
|
5 |
20 |
5000 |
100 |
1200 |
03:00 |
|
6 |
20 |
5000 |
100 |
1200 |
03:00 |
|
7 |
20 |
5000 |
100 |
1200 |
03:00 |
|
8 |
30 |
16000 |
80 |
800 |
12:00 |
|
9 |
30 |
5000 |
80 |
800 |
03:45 |
|
10 |
40 |
10000 |
60 |
500 |
10:00 |
|
11 |
40 |
5000 |
60 |
500 |
05:00 |
|
Route |
Links of the route |
Length [m] |
t0 [min] |
||
|
1 |
1+8+9 |
26000 |
|
|
18:45 |
|
2 |
1+2+3+5+6+7 |
30000 |
|
|
18:00 |
|
3 |
10+11+5+6+7 |
30000 |
|
|
24:00 |
|
LinkNo |
Volume |
tCur |
Volume |
tCur |
Volume |
tCur |
|
|
Step 1 (50%) |
Step 2 (25%) |
Step 3 (25%) |
|||
|
1 |
1000 |
05:05 |
1500 |
07:41 |
2000 |
11:20 |
|
2 |
1000 |
05:05 |
1000 |
05:05 |
1000 |
05:05 |
|
3 |
1000 |
05:05 |
1000 |
05:05 |
1000 |
05:05 |
|
5 |
1000 |
05:05 |
1000 |
05:05 |
1000 |
05:05 |
|
6 |
1000 |
05:05 |
1000 |
05:05 |
1000 |
05:05 |
|
7 |
1000 |
05:05 |
1000 |
05:05 |
1000 |
05:05 |
|
8 |
0 |
12:00 |
500 |
4:41 PM |
1000 |
30:45 |
|
9 |
0 |
03:45 |
500 |
05:13 |
1000 |
9:37 AM |
|
10 |
0 |
10:00 AM |
0 |
10:00 AM |
0 |
10:00 AM |
|
11 |
0 |
05:00 |
0 |
05:00 |
0 |
05:00 |
