20 th International Emme Users’ Conference Montreal, Quebec Thursday, October 19 th , 2006

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

2. 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) Snohomish Kitsap King Pierce

3. Overview – Basic Model Structure • 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 – www.psrc.org

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

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

6. Trip Purpose Breakdown

7. Rationale – Income Stratification • 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

8. 1999 HH Travel SurveyHH Income Categorization Combine Combine Combine Combine Stand Alone Stand Alone • 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

9. Home-Based WorkTrip 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 $CDN$ • 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

10. HH Income Data – 2000 Census • 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

11. Home-Based WorkTrip Production Rates • 65 Unique Classifications • HH Size/Workers in HH/HH Income Range

12. Home-Based WorkTrip Attraction Rates • Expedient/Straightforward • Based on Analysis of 2000 Census Data • HH Incomes of Workers by Industry

13. Home-Based WorkTrip Attraction Rates

14. 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)

15. Results – Distribution Average Trip Duration and Length by Purpose

16. Results – Distribution Intrazonal Trips and Travel Times by Trip Purpose

17. District-District Comparisons

18. District-District ComparisonIncome Class 1 (Obs. – Est.)

19. District-District ComparisonIncome Class 2 (Obs. – Est.)

20. District-District ComparisonIncome Class 3 (Obs. – Est.)

21. District-District ComparisonIncome Class 4 (Obs. – Est.)

22. District-District ComparisonAll Income Classes (Obs. – Est.)

23. 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

24. Observations • HB Work Trip Production Rates Increase as HH Income Increases

25. Observations Home-Based Work Trip Production Rates

26. Observations • 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

27. Observations HH Income Profiles of Workers by Industry

28. Observations • Average Trip Lengths Increase as HH Income Increases

29. Observations Average Trip Duration and Length by Purpose

30. Observations Intrazonal Trips and Travel Times by Trip Purpose

31. Observations • 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

32. Thinking Out Loud… • 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

33. Merci! Questions? Chris Johnson Puget Sound Regional Council 1011 Western Avenue, Suite 500 Seattle, WA 98104 tel 206 389 2876 fax 206 587 4825 cjohnson@psrc.org www.psrc.org