1. A Multiclass Dynamic Traffic Assignment Model for Special Events Management
12th TRB National Transportation Planning Applications Conference
May 17-21, 2009
Houston, Texas
Fang Yuan, Ph.D., P.E.
Karen Giese, P.E.
Kean Lew, P.Eng

2. Outline Model Background Dynamic Assignment
Pedestrian-Vehicle Interactions
Output

3. Geographic Context

4. Geographic Context

5. Geographic Context

6. Geographic Context

7. Model Context
City of Vancouver hosts many large special events, including 2010 Winter Olympic and Paralympic Games
Existing City analysis tools limited:
Planning for events in isolation
No future projection of impacts
The City sought to develop a special event planning tool that would:
Capture the travel patterns of pedestrians and vehicles during special events (including interactions between them)
Allow for the testing of alternative transportation networks and event demand profiles / schedules
Facilitate scenario development with limited input detail

8. Model Context (cont’d)
Existing pedestrian models generally fell into two categories:
Planning Models with limited consideration of pedestrian activity
Microsimulation Models with explicit pedestrian behavior modeling at an operational level, but limited route choice capabilities or vehicle modeling and high input burden
Solution:
Development of the Downtown Vancouver Transportation and Emergency Management System (DVTEMS)

9. DVTEMS Model Features Planning-level travel demand model
Focus on pedestrian route choice
Feature dynamic assignment
Based on the VISUM platform
Custom pedestrian-vehicle interactions
Communication through visual platform
Quantitative analysis

10. DVTEMS Model Application
Identification of Bottlenecks/Network Deficiencies
Pedestrian Management Strategies
Event Road Closure Plans
Special Event Impacts
Construction Road Closure Alternatives
Emergency Management Planning

11. DVTEMS Model Scope Study Area: Stadium District
Model Extents: Downtown Peninsula
24-hour Weekday (Friday) and Saturday
15-minute time intervals
Pedestrians and Vehicles
Calibrated Base (2007) and 2010

12. Dynamic Assignment Key Benefits (vs. Static Assignment)
Account for Special Event Temporal Characteristics
Account for Capacity Constraints and Changes
Model Proper Interaction of Real Flows
Model Impacts of Short-Term Measures
Present Congestion Phenomena

13. VISUM Dynamic User Equilibrium (DUE)
Model and solution by G. Gentile & L. Meschni of Univ. of Rome
Multi mode, multi user dynamic traffic assignment
Accept time-varying input attributes (e.g. capacity, mode)
Can handle spillback and departure time choice
Coarse time discretization (DVTEMS: 24-hr period in 15-min interval)
Macroscopic flow model (simplifed kinematic wave theory)
Parabolic/trapeodial fundamental diagram (instead of VDF)

14. VISUM Dynamic User Equilibrium (DUE)
Vehicles Flow Diagram

15. VISUM Dynamic User Equilibrium (DUE)
Pedestrian Flow Diagram

16. Modeling Pedestrian-Vehicle Interactions
No Interactions
Pedestrians use only sidewalk and cross roads at intersections
Two separate assignments
Controlled Interactions
Assign some roads (lanes) to pedestrians (e.g. special events):
ped capacity = sidewalk capacity + road capacity assigned to pedestrians
Perform pedestrian assignment with defined pedestrian capacity
Update car turn capacity according to pedestrian flows at intersections
Perform car assignment with updated link and turn capacities

17. Modeling Pedestrian-Vehicle Interactions
Random Interactions
Pedestrians may randomly and discontinuously take car capacity
Set predefined pedestrian capacity
Perform pedestrian assignment with pedestrian capacity
Update car turn capacity according to pedestrian flows at intersections
Reduce further car link capacity according to pedestrian flows on links
Perform car assignment with updated link and turn capacities

18. Custom Interactions in DVTEMS
Two-way Pedestrian Capacity
Allows Pedestrians to Utilize Both Sidewalks Along Street
Vehicle-Pedestrian Interaction at Intersections
Uses Actual Crosswalk Flows from Assignment
Pedestrian Inundation
Pedestrians Encroach on Vehicle Space
Vehicle Capacity Decreased
User-defined Parameters

19. Two-Way Sidewalk Capacity
Vehicle capacity = f (link width in one direction)
Ped capacity = f (link width in both directions AND ped volume)

20. Two-Way Sidewalk Capacity
Iteration 1:
Ped Capacity EB = Ped Capacity WB = f (link width in BOTH directions)
Initial Pedestrian Assignment: bi-directional flow for each link

21. Two-Way Sidewalk Capacity
Iteration 2 and Onward:
Ped Capacity EB = (Ped Vol EB / Total Ped Vol) * Total Ped Capacity
Ped Capacity WB = (Ped Vol WB / Total Ped Vol) * Total Ped Capacity
Continue Pedestrian Assignment Iterations until Convergence

22. Vehicle-Pedestrian Interaction at Intersections
Run Pedestrian Assignment to Obtain Flows for Each Crosswalk
Update Vehicle Turn Capacity = f (Ped Volumes)
Run Vehicle Assignment with Updated Vehicle Turn Capacity

23. Pedestrian Inundation
Pedestrian Encroachment on Vehicle Lane(s)
Parameters to be User-Defined (On or Off):
Inundation Allowed (Global Setting)
Pedestrian Link Density Threshold for Inundation (Global Setting)
On-Street Parking Allowed (Link Setting)
Pedestrian Allowed On Road (Link Setting)

24. Pedestrian Inundation
Link Density < Inundation Threshold
Link Density > Inundation Threshold
Link Density > Inundation Threshold

25. Pedestrian Inundation
Link Density > Inundation Threshold
Run Pedestrian Assignment to Obtain Flows and Capacity Required from Vehicle Network
Adjust Vehicle Link Capacity
Run Vehicle Assignment with Updated Vehicle Link Capacity

26. DVTEMS Model Output Volume by Time Interval and Mode
Pedestrian Density by Time Interval
Pedestrian Level of Service by Time Interval
Inundation Occurrence (Link Density > threshold and parameters allow for inundation)
Travel Times To/From Stadium by Mode

27. Example Scenario Results: Volumes, Density, LOS Over Time
Event 1 Start: 19:00
Pre-Event 2 Start: 18:50
Event 2 Start: 21:00
20:30
19:45
19:30
20:00
20:15
19:00
19:15
18:30
17:45
17:00
17:30
17:15
18:45
18:00
18:15
Output examples – pick some output to highlight
Volumes over time – show volumes changing over time
Queuing – show the volumes changing over time
LOS – show change in LOS and difference b/w 2 adjacent links based on sidewalk width

28. Example Scenario Results: Volumes, Density, LOS Over Time
Event 1 End: 21:30
Event 2 End: 23:00
22:15
23:00
23:30
23:45
22:30
23:15
22:45
21:00
21:45
21:30
22:00
21:15
Output examples – pick some output to highlight
Volumes over time – show volumes changing over time
Queuing – show the volumes changing over time
LOS – show change in LOS and difference b/w 2 adjacent links based on sidewalk width

29. Example Scenario Results: Link Closure
19:15

30. DVTEMS Future Expandability
Geographic and Temporal Expansion
Refined Pedestrian Route Choice through Real Data
Addition of New Scenarios
Re-word last bullet from VDF
Refinement of pedestrian route choice through real data

31. Presentation Dedicated to Kean Lew, P.Eng.
Questions and Discussion
Thank you for your attention.
Special thanks to:
University of Rome
City of Vancouver
Presentation Dedicated to Kean Lew, P.Eng.