Embed Size (px)
Citation preview
Spatial Resolution in SANDAG Activity-Based Model:
How Much More Detail Is Enough?
Spatial Resolution in SANDAG Activity-Based Model:
How Much More Detail Is Enough?
15th TRB National Transportation Planning Applications Conference, Columbus OH
May 18th, 2015
Wu Sun, Gregor Schroeder & Matt KeatingSan Diego Association of Governments (SANDAG)
BackgroundBackground
SANDAG Activity-Based Model (ABM) and Active Transportation (AT) Model
ABM/AT model applications Spatial resolution in models
2
Enhanced ABM
CTM
Trans. SystemTrans. Policy
Traffic Assignment
SystemPerformance
Environmental Impact
EconomicAnalysis
3
LU Models
Integrated ABM & AT ModelIntegrated ABM & AT Model
Special Models
bicycle & Ped Route Choices
Improved NM Impedance
Improved Mode Choices
AT Model
Spatial ResolutionSpatial Resolution
4
• MGRA (gray lines)
• 23002 MGRA
• 4996 TAZs
MGRA: Master Geographic Reference Area (Grey Lines)TAZ: Transportation Analysis Zone (Orange Line)
What Are Affected by Spatial Resolutions?
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
A Base ScenarioA Base Scenario
Path between zone 1 and 2 Path between zone 1 and 2
11
22
A Scenario with Smaller ZonesA Scenario with Smaller Zones
Path between zone 1 &1a and 2 Path between zone 1 &1a and 2
11
22
1a1a
How Spatial Resolutions Affect the Model?
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
Result AnalysisWalkability
Result AnalysisWalkability
9
Base Small Zones
6500000
7000000
7500000
8000000
8500000
9000000
9500000
Base Small Zones
100000
105000
110000
115000
120000
125000
130000
135000
Walkable zone pairs Walkable zone-TAP pairs
Result AnalysisAvg Walk Distance Btw Zones
Result AnalysisAvg Walk Distance Btw Zones
10
Avg_Walk_Dist Avg_WalkTransit_Dist0.50
0.70
0.90
1.10
1.30
1.50
1.70
1.90
2.10
BaseSmall Zones
Result AnalysisAvg Bike Distance Btw Zones
Result AnalysisAvg Bike Distance Btw Zones
11
Base Small Zones0
2
4
6
8
10
12
14
16
18
Result AnalysisTrips by Mode
Result AnalysisTrips by Mode
12
Trips Mode Shares
Mode Base Small Zones Diff Base (%)Small Zones (%) Diff %
Auto 8,944,716
8,938,479 -6237 85.40 85.35 -0.06%
Walk 1,063,005
1,065,769 2764 10.15 10.18 0.27%
Bike 101,848
114,498 12650 0.97 1.09 12.43%
Walk to Transit
202,856
192,762 -10094 1.94 1.84 -4.96%
Other Transit
19,506
19,410 -96 0.19 0.19 -0.48%
Other 142,582
142,384 -198 1.36 1.36 -0.13%
Total 10,474,513
10,473,302 100.00 100.00
Result AnalysisAvg Walk Trip Distance
Result AnalysisAvg Walk Trip Distance
13
Avg_Walk_Dist Avg_WalkTransit_Dist0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
BaseSmall Zones
Result AnalysisAvg Bike Trip Distance
Result AnalysisAvg Bike Trip Distance
14
Base Small Zones2.05
2.10
2.15
2.20
2.25
2.30
2.35
2.40
ConclusionsConclusions
• Finer spatial resolution• Improve walkability• Non-motorized trips increase and auto trips
decrease• Impact on bike trips more significant than on
walk trips
• How much more detail is enough?• What is important to you?• Other things to consider
15
