Overview of Travel Demand Modeling at WSDOT ER Planning 

Mike BjordahlTransportation Engineer

WSDOT Eastern Region Planning Office

18th Annual Northwest Tribal Transportation Symposium

April 20, 2011

“Th li t f t ti ti th t I id th t i 1975 I d ’t k h I“The same list of statistics that I saw said that in 1975—I don’t know why I should be bothering about that year, except that I have grandchildren—said there are going to be 80 million automobiles on our streets and roads and highways ”and highways.

President Eisenhower, 1954

http://www.fhwa.dot.gov/interstate/audiotext.htm#cadillac

http://www.fhwa.dot.gov/policyinformation/statistics/2009/pdf/dv1c.pdf

http://www.fhwa.dot.gov/policyinformation/statistics/2009/pdf/dv1c.pdf

Metropolitan Planning Organization (MPO)S k R i l T t ti C il (SRTC)Spokane Regional Transportation Council (SRTC)

Federally Mandated: 1962 Federal Legislation 50,000+ Population Region Wide 3 C’s: Continuing, Cooperative, and Comprehensive Supply us with the regional model

Travel Demand Modelingg

Travel Demand Modelingg

Travel Demand Modeling

THE FOUR STEP MODEL1. TRIP GENERATION2. TRIP DISTRIBUTION3. MODE CHOICE4. TRIP ASSIGNMENT

Trip Generationp

House Trip Gen: 2 Home Based Work (HBW) and 2 Home Based School (HBS)

Trip GenerationT t ti A l i Z (TAZ)Transportation Analysis Zone (TAZ)

Trip Generationp

Productions/Origins Attractions/DestinationsProductions/Origins Attractions/Destinations

Trip Distributionp

Mode Choice

Mode Choice

Mode Choice

Trip Assignmentp g

Trip Assignment“Flow Bundle”Flow Bundle

North Spokane Corridorp

North Spokane Corridor

North Spokane CorridorU d C t tiUnder Construction

VISUM Difference Network showing Predicted Shift from North/South Local Arterials to the NSC/

Link Volume toLink Volume to Capacity Ratios

Node Volume to Capacity Ratiosp y

2005

2010

Turn Volumes

Model to Count Comparison

Post ProcessingNCHRP 255 Methodology

Factoring Procedures for Turning Movements

ff Difference

Ratio

Combined

If Needed, Engineering Judgment

SourcesBeimborn, Edward A. A Transportation Modeling Primer. 1995

Transportation Research Board. NCHRP 255 ‐ Highway Traffic Data for Urbanized Area Project Planning and Design 1982Project Planning and Design. 1982

PTV America, Inc. PTV Vision – Tutorial Four‐Step Demand Modeling with VISUM. Corvallis, OR, 2007

Travel Model Improvement Program (http://tmip.fhwa.dot.gov/)Travel Model Improvement Program (http://tmip.fhwa.dot.gov/)