Example: Using the decision model to calculate a managed lane
The ratio of the coefficients Utility Coefficient Toll and Utility Coefficient Time is decisive for modeling real traffic conditions. With the default values Utility Coefficient Toll = -1 and Utility Coefficient Time = 0.4, one monetary unit is worth as much as a travel time saving of 2.5 min.
If Logit alpha = 0.05: Increasing the base utility by 20 increases the ratio of probabilities for and against the managed lane by factor e (2.718):
- With Logit alpha = 0 and a base utility = 40 for HOV (heavy occupancy vehicles) vehicles, for each minute saved by using the managed lanes, the share of HOV vehicles on the normal lane is divided by 7. For two minutes the result is 1/e^4 = about 1/55.
- When you wish to model that most of the HOV vehicles already use the managed lane though the time saving is not known yet, set the base utility accordingly: A base utility of 20, for example, results in that even with utility = 0 (unknown travel time gain) only 1/(1+e) (about 27%) of the vehicles will travel on the normal lane.
| Alpha ● Utility | Managed lane probability |
|---|---|
|
2 |
87 % |
|
1.5 |
82 % |
|
1 |
73 % |
|
0.5 |
62 % |
|
0 |
50 % |
|
- 0.5 |
38 % |
|
- 1.0 |
27 % |
|
- 1.5 |
18 % |
|
- 2.0 |
13 % |
If you increase the base utility by 10, with Alpha = 0.05, the value of Alpha ● Utility increases by 0.5. The probability increases accordingly.
