Income-Based Work Trip Stratification within the Puget Sound Regional Council Travel Model Framework 20 th International Emme Users’ Conference Montreal, Quebec Thursday, October 19 th, 2006 Chris Johnson Puget Sound Regional Council

Seattle, Washington USA Membership King, Kitsap, Pierce and Snohomish Counties 70 cities 4 Ports Tribes State agencies 7 Transit agencies Associate members 3.4 million residents (+1.7 million by 2040) 1.9 million jobs (+1.2 million by 2040) King Kitsap Pierce Snohomish

Traditional 4-Step (Trip Based) 938 Zone/19,000 Link Network Trip Generation – Cross Classification Trip Distribution – Gravity Mode Choice – Multinomial/Nested Logit, Non-Motorized Modes Time-of-Day (AM Peak Period, Mid-Day, PM Peak Period, Evening, Night) Assignment – Multi-Class (11), Generalized Cost Full Documentation – Overview – Basic Model Structure

Model Process Land Use and Travel Demand Forecasting Process Trip Purposes (10): Home-Based Work (4) Other Shopping School (K – 12) College (Households & Dormitories) Non Home-Based Work/Other Other/Other

Home-Based Work Income Stratification within: Trip Generation Trip Distribution Approach/Structure/Processes Results Observations Final Thoughts Today’s Focus

Trip Purpose Breakdown

Built-In Structure not being used – Easily Implemented Capture Trip-Making Differences among the Different Income Groups Achieve a Better Match between Household and Job Locations Position Model for Evaluation/Analysis of Tolling/Pricing Policies Rationale – Income Stratification

Less than $10,000 $10,000 – $14,999 $15,000 – $24,999 $25,000 – $34,999 $35,000 – $44,999 $45,000 – $54,999 $55,000 – $74,999 $75,000 or More 1999 HH Travel Survey HH Income Categorization Stand Alone Combine

Income Class Stratification: Less than $15,000 HH Income $15,000 – $24,999 HH Income $25,000 - $44,999 HH Income $45,000 - $74,999 HH Income $75,000 or more HH Income Categorization from 1999 HH Travel Survey Sum Productions in Bottom Ranges before Distribution Single Range – Less than $24,999 HH Income Home-Based Work Trip Production Rates Less than $16,000 HH Income $16,000 – $26,599 HH Income $26,600 – $47,899 HH Income $47,900 – $79,799 HH Income $79,800 or more HH Income $CDN$

2000 Median HH Income: King – $53,000 Kitsap – $47,000 Pierce – $45,000 Snohomish – $53,000 Regional HH Income Distribution: Less than $24,999 = 20.6% of Households More than $75,000 = 29.2% of Households HH Income Data – 2000 Census

Home-Based Work Trip Production Rates 65 Unique Classifications HH Size/Workers in HH/HH Income Range

Home-Based Work Trip Attraction Rates Expedient/Straightforward Based on Analysis of 2000 Census Data HH Incomes of Workers by Industry

Home-Based Work Trip Attraction Rates

Quick Recap Calculate HB Work Productions for 5 Income Classes Sum Lowest 2 Classes (Less than $25,000) Calculate HB Work Attractions for 4 Income Classes Distribute HB Work Trips for 4 Income Classes Gravity Composite Impedances (log sums)

Results – Distribution Average Trip Duration and Length by Purpose

Results – Distribution Intrazonal Trips and Travel Times by Trip Purpose

District-District Comparisons

District-District Comparison Income Class 1 (Obs. – Est.)

District-District Comparison Income Class 2 (Obs. – Est.)

District-District Comparison Income Class 3 (Obs. – Est.)

District-District Comparison Income Class 4 (Obs. – Est.)

District-District Comparison All Income Classes (Obs. – Est.)

Results: District-District Validation Most Trips, Regardless of Income Class are Intra- District Some Discrepancies (both Intra- and Inter-District) Exist and Should be Further Investigated Overall (All Income Classes) District-District Comparison Appears Acceptable

HB Work Trip Production Rates Increase as HH Income Increases Observations

Home-Based Work Trip Production Rates

Trip Rate Differences Less Evident on Attraction Side Government – Highest Low Income, Lowest High Income Manufacturing – Lowest Low Income, Highest High Income Retail – Percent of High Income HHs is Surprising Observations

HH Income Profiles of Workers by Industry

Average Trip Lengths Increase as HH Income Increases Observations

Average Trip Duration and Length by Purpose

Observations Intrazonal Trips and Travel Times by Trip Purpose

HB Work Trip Production Rates Increase as HH Income Increases Trip Rate Differences Less Evident on Attraction Side Government – Highest Low Income, Lowest High Income Manufacturing – Lowest Low Income, Highest High Income Retail – Percent of High Income HHs is Surprising Average Trip Lengths Increase as HH Income Increases Valid Distribution Model Observations

Zone Size Smaller Zones Would Allow for Easier Isolation of Higher/Lower Income Neighborhoods Or Does Zone Size Matter? More Refined Income Brackets $75,000+ Probably Too Low for the Highest Income Range −$75,000 – $100,000 = 13.4% (2000 Census) −More than $100,000 = 15.8% (2000 Census) 2006 HH Survey – Category with $100,000+ Why the Trip Production Rate Differences? Would Tours Show Same Differences? Will these Production Rates Stay Constant Over Time – 2040? Will these Income Profiles by Industry Stay Constant Over Time – 2040? Occupation vs. Industry Data – Occupation-based Data May Be More Reflective of Income (I.e., Management vs. Sales vs. Service vs. Retail) More Geographic Analysis Thinking Out Loud…

Merci! Questions? Chris Johnson Puget Sound Regional Council 1011 Western Avenue, Suite 500 Seattle, WA tel fax