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NCTCOG And“Next Generation” Modeling
Ken Cervenka, P.E., AICP
North Central Texas Council Of Governments
For
AMPO Travel Modeling Work Group Meeting
Kansas City, Missouri
September 28, 2004
Agenda
Current Modeling Environment
Multi-Year Network Coding
Next Steps—Near Term
Next Steps—Taking The Plunge
4,536,010
6,671,351
4,848,237
5,650,339
7,952,0708,503,146
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
8,000,000
9,000,000
10,000,000
1995 2000 2005 2010 2015 2020 2025 2030 2035 2040
Previous Plan Demographics (Mobility 2025 Update) New Plan Demographics (Mobility 2025, 2004 Update)
(Previous Plan)
(New Plan)
Total Population Within The Dallas – Fort Worth Metropolitan Planning Area
Four-Step Modeling Process
TRIP GENERATION
TRIP DISTRIBUTION
MODE CHOICE
ROADWAY ASSIGNMENT
TRAVEL TIMECONVERGENC
E
TRANSIT ASSIGNMENT
NO
YES
ZONE LAYERDEMOGRAPHIC INFORMATION
ROADWAY NETWORK
TRANSIT NETWORK
LOOPROADWAY SKIMS
TRANSIT SKIMS
INPUT
PROCESS
DECISION
Trip Distribution
Gamma-Format Gravity Model (7 Purposes) Four HBW Groups (Income Quartiles) – AM Peak HNW (Non-Airport) – OffPeak NHB (Non-Airport) – OffPeak Trucks (Vehicles With Six Or More Tires) – OffPeak
Base Year Trip Table Factoring (6 Purposes) HNW And NHB Airport Trips Four External-Related Auto/Truck Trips
Market Segmentation
To Account For Differences In Commuter Behavior
Segmentation Basis (6 HBW And 6 HNW)
– Household Income (3)• Low
• Medium
• High
– Vehicle Availability For A Household (2)• Vehicles Less Than Persons
• Vehicles Greater Than Or Equal To Persons
Traffic Assignment
User Equilibrium Generalized Cost (Three 30-Iteration Assignments) A.M. Peak (6:30a – 8:59a: 2.5 hours) P.M. Peak (3:00p – 6:29p: 3.5 hours) OffPeak (18 hours)
Four Vehicle Classes Loaded Simultaneously Drive Alone (Sees HOV-Toll Lanes As Tolled) Shared-Ride (Sees All HOV Lanes As Free) Shared-Ride (Doesn’t See Any HOV) Trucks (Vehicles With 6 Or More Tires)
What Happens Next For NCTCOG
Training NCTCOG Staff Dallas Area Rapid Transit (DART) Staff Other Agencies (Local/TxDOT) Certification Of Consultants??? Model Implementers, Model Users, And Application Champions
Model Documentation Include The “What” As Well As The “Why” How To Run The Model/How To Understand The Model
What Happens Next (Cont.)
Possible Model Updates (0 - 3 Years) More Output Report Summaries (Tables, Graphs, Maps) Tests Of “Generic” Transit Skim/Mode Choice Procedures LOGSUM Consistencies Destination Choice Instead Of Gravity Model Trip Distribution Expansion Of Modeled Area Updated Land Use Modeling Tools Additional Time Periods For Traffic Assignment
Coordination With TxDOT Statewide Analysis Model
Traffic Microsimulation For Subarea Operations Analysis
Transit Model Outputs:Supply-Side Calculations
Number Of Coded Transit Lines
Roadway Network Links (Or Miles) With Transit
Total Physical Stops And “Transit Line” Stops How Many Are Rail Stations How Many Are Transit Park-And-Ride Locations
AM Peak And Mid-Day OffPeak Vehicle Miles AndHours Of Travel
Population And Employment Within “Buffer” Areas
Transit Model Outputs:Demand-Side Calculations
Transit Boardings And Alightings By Mode, By Route, By Line, Or By Rail Station For Weekday, Or For Each Of Four Assignments
Average Transfer Rates Boardings, Riders, And Boardings Per Rider
Transit Passenger Miles And Hours
Rail Station Mode-Of-Access/Egress Summaries
Multi-Year Network Concept
One Link/Node Layer And One Transit Route Layer ForALL Years Contains ALL Streets Essentially A 25-Year TIP!
Travel Model Network Extracted From All Streets Layer Link And Route Selections Based On Start And End Date Fields Local And Non-MPA Street Links Excluded
Example: Blue Street Links Are Extracted To Travel Model Links
Agency's "Master Roadway Layer"
Covers 16-County NCTCOG Area
2003 Digital Aerial Photos (Six Inch)
Example: Future-Year Interchange
Single-Point Intersection
Network Coding Environment
Agency's ArcGIS Layer
TransCAD Multi-Year Network
Roadway/Transit Corridor Study
Agency's ArcGIS Layer
TransCAD Multi-Year Network
Alternatives
Agency's ArcGIS Layer
TransCAD Multi-Year Network
Final Recommendations
UpdatesUpdates
Updates
Checks
Checks
Updates
Checks
(Do Once)(Frequently)
GIS Database Integration
TransCAD Multi-Year Network
ArcGIS TIP/AQ Database and
Layer
ArcGIS Multi-Year Integrated
Layer
Other Databases/LayersTraffic Counts (Access)ITS Data (SQL)Skycomp Data (Access)GPS-Based Travel TimesAccidentsAt-Grade RR CrossingsIntersection Details
Export
Web-BasedInteractiveDisplays
Some Tough Issues
True Multi-Year Coding Is A Complex Environment But Allows For Greater Consistency/Quality Control
Between Travel Model Years (And With TIP)
Traffic Counts And Detailed Roadway Data
(Including Traffic/Transit Projections): Should We Put Everything On the Web?
Who Pays For The Initial Collection Costs?
Is Everything Free To The End User?
Should We Be Concerned About Possible Misuse?
Taking The Plunge:Activity-Based (AB) Modeling
Maybe It Is “Put Up Or Shut Up” Time! We Must Find Out Where Things Stand
Rigorous Sensitivity Tests Of Estimated Models
NCTCOG Can Test CEMDAP (UT-Austin/DFW Data)
Other Agencies Can Test Other AB Model Brands
Major Issues For Resolution: Current Worthiness And Readiness Of AB Models
Spatial/Temporal Transferability Of Formulations/Estimations
If Not Ready: Realistic Costs And Timeframes For Improvements
Simple Sensitivity Tests (Examples)
Global Increase/Decrease Of Input Variables
Area-Specific Increase/Decrease Of Input Variables
Check Local/Regional Change In Travel Patterns
Check Local/Regional Change In Person Miles
Perform Same Tests With Implemented Four-Step Model
If Current Activity-Based Model Formulations/Estimations Aren’t
Ready For The Real World:
Form An MPO (Or MPO/DOT) Consortium Pooled Funding/Staff Resources Pooled Survey Data And Network Skims Identify Realistic Project Scope Competitive Procurement Of University/Consultant Team Independent Review Panel/Paid Workgroup Team Quarterly Meetings For Sponsors To Measure Progress Public Exposure May Help Keep Everyone Honest/Objective Must Deal With Proprietary Software Issues
Desired Results ForPooled Funding Effort
Applied Research Conducted In An Orderly Fashion Does A New Theory/Latest Fad “Smell” Right?
Each Model Calibration/Validation Effort BuildsUpon Successes/Failures Of Previous Implementations
Provide Support For New Basic Research Discourage A Start-From-Scratch Mentality
For E-Copy Of This Presentation
Type In This URL:
http://www.dfwinfo.com/trans/program_areas/travel_forecasting.html
Or Simply Google On:
“NCTCOG Travel Forecasting Program”
And Look Under “Travel Forecasting Presentations”
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