1. Parcel-level Measure of Public Transit Accessibility to Destinations Brian H. Y. Lee Urban Design & Planning University of Washington 19 Nov 2004 TransNow Student Conference Portland State University

2. Outline +Problem +Current solutions +Proposed method +Test case +Final words

3. Public Transit Accessibility +Fundamentally different mode of urban transport +Complex spatial & temporal components +Multi-modal, walking

4. Measurement Approaches +Access to & from public transit network +Spatial focus +Zonal aggregation (e.g., TAZ)

5. Implications +Exaggerate benefits +Incomplete picture +Estimations & forecasts evaluations & policies

6. Current Techniques +Area buffers (400m radius) Area ratios +Network buffers Bedroom ratios (Zhao et al., 2003) 1. Stop & Station Catchment:

7. Current Techniques, cont. 2. Accessibility to Destinations: +Most gravity-based +Zonal approach +Broad categories of destinations

8. Conceptual Framework +Classification of land uses +Total travel time +Single type of destination or Combination of different types +E.g., accessibility to grocery stores

9. Measurement process (A) Identify destinations (B1) Identify all stops (within 400m) (B2) Calc. walk time from each stop (B4) Calc. avg. wait time at each stop (1/2 headway) (B5) Identify all accessible parcels (within 400m) (C1) Identify all accessible parcels (within 1,000m) (D) Choose min. travel time (E) Associate other data (B3) Calc. travel time from upstream stops (B6) Calc. walk access time from parcels (B7) Sum total travel time (C2) Calc. walk access time TransitWalk

10. Test Case Application +King County Metro - Buses +One grocery store location +Accessibility measurement & population estimate +Area buffer & ratio: “Area ratio” +Parcel-level – spatial: “Simplified parcel” +Parcel-level – spatial & temporal: “Proposed parcel”

11. Area Ratio Method

12. Simplifed Parcel Method (res. only)

13. Proposed Parcel Method (res. only) } 45+ min

14. Area RatioSimplified ParcelProposed Parcel

15. Census Tract Total Pop’n Estimated Populations ServedRatio Area Ratio [A] Simplified Parcel [B] Proposed Parcel [C] [A]/[C][B]/[C] 44001,59714210 14.281 4500923300n/a 52003,2608743963912.231.01 53018,5095,5584,949 1.121 53022,528960348 2.761 58022,016300n/a 62003,8002,2763,0372,9740.771.02 64003,2013,1142,6812,6311.181.02 65001,5119158317881.161.05 70004,7442,3552,1832,1311.101.02 71001,8091,1581,183 0.981 72003,0842,4391,483 1.641 73002,2181,6531,2831,2711.301.01 74008,9326,8386,3136,3071.081.00 … ……………… Total124,15271,28364,30158,5051.221.10 Percent 100%57.4%51.8%47.1%

16. Limitations +Land use classifications +Estimation of waiting times +Monetary costs +Other transit service characteristics

17. Conclusions & Recommendations +Informative graphical results +Realistic (conservative) estimates +Potentials for modeling applications +Streamline data management & processing

18. THE END