Parcellevel Measure of Public Transit Accessibility to Destinations

1
Parcel-level Measure ofPublic Transit
Accessibilityto 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 differentmode of urban transport
• Complex spatial temporal components
• Multi-modal,walking

4
Measurement Approaches

• Access to frompublic transit network
• Spatial focus
• Zonal aggregation (e.g., TAZ)

5
Implications

• Exaggerate benefits
• Incomplete picture
• Estimations forecastsevaluations policies

6
Current Techniques

1. Stop Station Catchment

• Area buffers(400m radius)Area ratios

• Network buffersBedroom ratios(Zhao et al.,
  2003)

7
Current Techniques, cont.

• 2. Accessibility to Destinations
• Most gravity-based
• Zonal approach
• Broad categoriesof destinations

8
Conceptual Framework

• Classification of land uses
• Total travel time
• Single type of destination orCombination of
  different types
• E.g., accessibility togrocery stores

9
Measurement process
(A) Identify destinations
Transit
Walk
(B1) Identify all stops (within 400m)
(C1) Identify all accessible parcels (within
1,000m)
(B2) Calc. walk time from each stop
(B3) Calc. travel time from upstream stops
(B4) Calc. avg. wait time at each stop(1/2
headway)
(B5) Identify all accessible parcels(within 400m)
(B6) Calc. walk access time from parcels
(C2) Calc. walk access time
(B7) Sum total travel time
(D) Choose min. travel time
(E) Associate other data
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 Ratio
Simplified Parcel
Proposed Parcel
15
(No Transcript)
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