1. Use of Journey Levels for Hierarchical Transit Assignment
Ilan Elgar
Model City Portland, September 20, 2016

2. Journey Level Assignment (JLA)
A new INRO module for assigning transit trips
Useful for transit networks with complicated fare strategies
Useful for hierarchical transit assignment

3. Metro Vancouver

4. Transit Commute Patterns

5. Transit Discretionary Patterns

6. Transit Network
See if we can overlay this on a map/aeriel of MV

7. Transit Network (in the model)
See if we can overlay this on a map/aeriel of MV

8. Model Formulation Trip based model
The mode choice model generates separate bus and RT O-D tables
In the assignment stage bus and RT are treated hierarchically

9. How to prevent trips in the RT assignment from using bus only?
Problem
How to prevent trips in the RT assignment from using bus only?

10. Option 1 – Use Penalties Costs in the rapid transit assignment
The ‘3.5’ bus IVTT factor ensures that RT trips actually use RT in the assignment stage.
Use of the ‘3.5’ allowed calibration of the model at a regional scale
Time Component
Calculation (min)
Perception (weight)
Waiting
1/2 Headway
2.25
Walking
Walking Speed (4.8kph)
1.75
In-Vehicle (Bus)
Bus Travel Time
3.5
In-Vehicle (RT)
RT Travel Time 1
Boarding
1 Minute 4

11. Issues with Using Penalties
But, at a local level the factor skewed network costs and generated counterintuitive paths
1.5M

12. Option 2 – Use JLA
The Journey Levels Assignment is a new tool added to EMME with version 4.2 (2015)
JLA only allows paths that meet certain Journey criteria
Trips are essentially tagged as RT trips
The JLA does not allow RT trips to end until a RT segment is used
Costs in rapid transit assignment
Time Component
Calculation (min)
Perception (weight)
Waiting
1/2 Headway
2.25
Walking
Walking Speed (4.8kph)
1.75
In-Vehicle
Transit Travel Time 1
Boarding
1 Minute 4

13. JLA - Testing JLA by itself produces counterintuitive results
The assignment algorithm asks whether the mode (rail) is part of the optimal strategy (IVTT>0) and if so it’s part of the choice-set, otherwise it’s not (IVTT=0). When we run the JLA, we use the regular (optimal strategy assignment and 3.5 bus factor) to determine the choice-set and then optimize the routes using the JLA procedure.
“The main reason this happens is because the mode choice models were estimated and calibrated using the ‘3.5’ factor. This factor eliminated rail as an option from several O-D pairs in the estimation dataset. As such, the estimated coefficients (specially the generalized cost coefficient) are not ‘in sync’ with the skims resulting from the JLA assignment. “

14. JLA - Testing

15. Solution
Choice-set procedure in mode choice model needs to be tightened to filter out nonsensical RT use
Hybrid JLA procedure using filtering criteria
Assign RT trips using the 3.5 factor
Filter out O-D pairs that should not have RT availability
Reassign the remaining O-Ds using JLA to generate paths and costs

16. Outcomes of Hybrid Approach
Results relatively stable with improved paths

17. Outcomes of Hybrid Approach
Bus usage (as access mode) increases
Walk time access decreases

18. JLA Future Directions Improve choice-set definition
Max ratio of time spent on bus vs RT
Max amount of time spent on bus
RT trip time <1.5 Bus time
Use of JLA for complicated fare schemes
The next version of the model will separate between commuter train (WCE) and the rest of the rail system. The commuter rail is considered a premium service and has a different fare structure, rates and rules than the other transit modes. JLA will be used to assign ridership between the systems.