1. Spatial Resolution in SANDAG Activity-Based Model: How Much More Detail Is Enough? 15th TRB National Transportation Planning Applications Conference, Columbus OH May 18 th, 2015 Wu Sun, Gregor Schroeder & Matt Keating San Diego Association of Governments (SANDAG)

2. Background  SANDAG Activity-Based Model (ABM) and Active Transportation (AT) Model  ABM/AT model applications  Spatial resolution in models 2

3. Enhanced ABM CTM Trans. System Trans. Policy Traffic Assignment System Performance Environmental Impact Economic Analysis 3 LU Models Integrated ABM & AT Model Special Models bicycle & Ped Route Choices Improved NM Impedance Improved Mode Choices AT Model

4. Spatial Resolution 4 MGRA (gray lines) 23002 MGRA 4996 TAZs MGRA: Master Geographic Reference Area (Grey Lines) TAZ: Transportation Analysis Zone (Orange Line)

5. What Are Affected by Spatial Resolutions?  Land use inputs  Synthetic population  Non-motorized impedances –MGRA-MGRA walk –MGRA-MGRA bike  Transit impedances –MGRA-TAP walk  Highway impedances? 5 Vary by scenario

6. A Base Scenario Path between zone 1 and 2 1 1 2 2

7. A Scenario with Smaller Zones Path between zone 1 &1a and 2 1 1 2 2 1a

8. How Spatial Resolutions Affect the Model?  Demand side –Location choices: tour, trip, and parking locations –Other choices?  Supply side –Skimming: walk, bike, transit, and highway. –Highway assignment? –Transit assignment? 8

9. Result Analysis Walkability 9 Walkable zone pairsWalkable zone-TAP pairs

10. Result Analysis Avg Walk Distance Btw Zones 10

11. Result Analysis Avg Bike Distance Btw Zones 11

12. Result Analysis Trips by Mode 12 TripsMode Shares ModeBaseSmall ZonesDiffBase (%) Small Zones (%)Diff % Auto 8,944,716 8,938,479-623785.4085.35-0.06% Walk 1,063,005 1,065,769276410.1510.180.27% Bike 101,848 114,498126500.971.0912.43% Walk to Transit 202,856 192,762-100941.941.84-4.96% Other Transit 19,506 19,410-960.19 -0.48% Other 142,582 142,384-1981.36 -0.13% Total 10,474,513 10,473,302 100.00

13. Result Analysis Avg Walk Trip Distance 13

14. Result Analysis Avg Bike Trip Distance 14

15. Conclusions Finer spatial resolutionFiner spatial resolution Improve walkabilityImprove walkability Non-motorized trips increase and auto trips decreaseNon-motorized trips increase and auto trips decrease Impact on bike trips more significant than on walk tripsImpact on bike trips more significant than on walk trips How much more detail is enough?How much more detail is enough? What is important to you?What is important to you? Other things to considerOther things to consider 15

16. Questions?  Contact: Wu Sun  619-6995757  Wu.Sun@sandag.org