Transcript Slide 1
Dynamic Traffic Assignment
and Applications in the Twin
Cities Area
Steve Wilson
SRF Consulting Group
Duluth, Minnesota
August, 2008
Outline
Background/FHWA Support
35W Bridge Project
Test Applications
FHWA DTA Ongoing Development
What is Dynamic Traffic
Assignment (DTA)?
Mesoscopic traffic assignment model
– More responsive to operational factors
(queuing) than traditional travel demand
models
– More responsive to system level factors
(route-changing) than traditional
operations models
Travel Demand Model
Assignment Limitations
Trips are instantaneously on all links
between origin to destination (not
time-dependent)
Congestion delay does not adequately
reflect bottlenecks (upstream or
downstream)
DTA Models Availability
Federal Highways DTA
Commercial Vendors
– CITILABS
– TRANSCAD
– PTV
– EMME/2
– Others
FHWA DTA (TrEPS) Program
Started in 1995
Two parallel tracks (Real-time ITS and
Operational Planning)
Linking planning and operations
– Concept of “Operational Planning”
Fill in the traffic analysis tool gap
– Macroscopic (static, regional)
– Mesoscopic (dynamic, regional)
– Microscopic (dynamic, corridor)
Integration with TDM and microscopic model
Program Activities
DTA concept education and outreach
– Webinars (online) – several per year
– Short seminar (0.5-1 day) – on demand
– Workshops (2.5 day) – 2 to 3 per year
Mn/DOT (September 2008)
Program Activities
Technical support to state agencies
– MPO/DOT – FHWA division – Resource
center – FHWA HQ or TFHRC
– Educational Support
Training for DTA concepts
– Modeling Support
Assist in initial modeling and dataset buildup
Can be extended to consultants for a federally
funded project
Matching-fund may be needed if more
involvement is requested
M&O Status (updated May 2008)
State Users
Workshops held
Future Workshops
(TBD)
Initial Development of Twin
Cities FHWA DTA Model
I-35W Bridge
Collapse
FHWA Response
Pace of Study
MnDOT Model
Development
Importing of regional TDF model
network
Importing of regional TDF model trip
tables
Network cleaning
Simplified traffic control assumptions
MnDOT Model
Development
Calibration/adjustment of O-D
matrices
Testing of routing/improvement
scenarios
Initial Development of
Twin Cities FHWA DTA
Model
I-35W Bridge
Collapse
FHWA Response
Pace of Study
I-35W UPA Project
UPA Program
Competition
Innovative, multimodal, priced
Open by end of
2009
I-35W UPA Project
Priced dynamic shoulder
lane segment
Addition of a HOT lane in
Crosstown reconstruction
project
Conversion of existing HOV
lane to HOT lane
Also: BRT advanced
implementation, park-ride,
ITS
Why Dynamic Traffic
Assignment?
Availability
Better MOEs for comparison of
Alternatives
High-level operational evaluation
HOT lane capabilities
Why Not Dynamic Traffic
Assignment?
Availability/readiness
Memory/CPU resources
Learning curve
Traffic engineers’ comfort zone
Analysis
(Top 20 O-D pairs impacted by
bridge collapse)
119
123 124
443
444
426
424 423
414 359
371 372
373
337
334 337
335336 339
340 341
322321 318
514
421
420
Twin Cities FHWA DTA
Model
Departure Time (min)
230
210
190
170
150
130
110
90
70
50
30
10
10
0
w
Departure Time (min)
wo
Departure Time (min)
Total
20
230
30
210
40
190
50
170
60
150
408
230
210
190
170
150
130
110
90
409
130
wo
110
w
70
0
90
10
50
20
70
30
30
40
50
Departure Time(min)
10
50
Travel Time (min)
60
30
70
Travel Time (min)
230
210
190
170
150
130
110
90
70
50
30
10
Travel Time (min)
70
10
Travel Time (min)
Travel time into Downtown
area
410
90
80
70
60
50
40
30
20
10
0
w
407
wo
70
60
50
40
30
20
10
0
w
wo
FHWA DTA Model
(Subarea)
Learning Curve
“CORSIM-like”
Wiki help system
Model Integration w/ TDF softwares
FHWA DTA HOT Lane
Options
Distance-based
Link-based
Zone-based (coming soon)
FHWA DTA HOT Lane
Options Flexibility
Multiple User Class
Flexibility
Flexible Traffic Flow
Model
Exportable Tabular
Output
Graphic Output
Time Stream Comparisons
FHWA DTA Tests
(with subarea model)
Sensitivity to geometric changes
– Through lane add
– Auxiliary lane add
– Bottleneck queuing
Stadium event departure
Peak-segment ramp O-D volumes
Best Candidate DTA Uses
Evacuation Planning
Work zones
Systems Planning
Value pricing/HOT Lanes
Benefit-Cost Analysis
Travel demand model feedback
Lessons Learned
New DTA model not short-term response
Integration with planning/simulation models
Role of DTA in project development process
FHWA DTA V2.0
Modeling Features
Lane-group based Anisotropic Mesoscopic
Simulation (AMS) models
Relative gap gradient based assignment algorithm
Epoch implementation for 24-hour to multi-day
assignment
Destination and origin-based time-dependent leastcost path algorithms for various applications
Vertical integration with TDM and VISSIM
2008 Projects and
Applications Outlook
In progress
– Military Deployment Transportation Improvement in Guam (PB,
FHWA)
– Interstate highway corridor improvement (TTI, TxDOT, ELPMPO)
– Value Pricing (ORNL, FHWA; SRF, Mn/DOT, TTI, TxDOT)
– Evacuation operational planning (UA, ADOT; LSU, LDOT; Noblis,
FHWA; U of Toronto)
– Integrated Corridor Management modeling (CS, FHWA)
– Bay area regional modeling (CS, MTC)
– Florida turnpike system traffic and evacuation analysis (FDOT
Turnpike)
– Commercial development traffic improvement (PAG)
Future Outreach Activities
Arizona
– Workshop (July 29-31, jointly funded by MAG
and FHWA)
Minnesota
– Mn/DOT workshop (September 09)
California
– CalTrans and CA MPOs (August 11-13, 2008)
2-3 Kick-the-Tire webinars (FY 09)
2-3 Training workshops (FY 09)
FHWA DTA V2.0
Modeling Features
Suite of supporting tools to facilitate model use:
– Pre-processing
Network cleaning
Demand integration
– Post-processing
Time-space diagrams
Time-varying link statistics reports
Cumulative arrival curves
Impacted vehicle analysis
Vehicle path analysis
Acknowledgements
FHWA
– Jim McCarthy
– Chung Tran
Mn/DOT Planning Division
– Brian Isaacson
– Mark Filipi
– Tony Fischer
DynusT Labs
– Yi-Chang Chiu, University of Arizona
Questions?
Steve Wilson
[email protected]