san francisco county transportation authority san francisco’s dynamic traffic assignment model...
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SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
San Francisco’s Dynamic Traffic Assignment Model
Background
SFCTA DTA Model Peer Review Panel MeetingJuly 25th, 2012
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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Outline
• Project Background• Modeling tool suite
• SF-CHAMP 4.3.0 Fury• Previous DTA work
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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SF-CHAMP
• Simulates the travel pattern of every Bay Area Resident based on:• Demographics• Land use• Transportation Network
SF-CHAMP Model Basics 4
SF-CHAMP
HOME
WORK
INTERMEDIATE STOP ON WAY TO WORK
WORK-BASEDDESTINATION
HOME-BASED TOURDESTINATION
1
7
6
5
4 3
2
= Tour
= Trip
Number indicates trip order
PRIMARY TOUR:Home-based Work
WORK-BASEDSUB-TOUR
SECONDARY HOME-BASED
TOUR
Primary destinations vs.Intermediate stops
Consequences of choices: Do you have a car available? Did you leave the car at home? Do you have a complicated day?
A tour is an entire chain of trips: from your primary origin, to all of your destinations, and then back again.
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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SF-CHAMP Data
• Most models BATS 1996• New estimations (BATS 2000):
• Mode choice • Auto Availability
• New calibration (ACS)• Workplace Location Choice• Auto Availability• Tour mode choice
• New validation • 2010 APCs and Ridership• Recent Traffic Counts
SF-CHAMP Model Basics 6
CHAMP SEQUENCING – PART 1
Workplace locationVehicle Availability:
Accessibility of home Accessibility of work Accessibility between home and work
Tours Generated Accessibility of home Accessibility of work Accessibility between home and work
Initially Schedule ToursPrimary destinations for non-work tours
Initial tour schedule Accessibility
SF-CHAMP Model Basics 7
CHAMP SEQUENCING – PART 2
Tour scheduling Accessibility by time of day for chosen
destinationTour mode
Accessibility to destinations for that time of day by mode
Choose intermediate stops along tours (tours become trips)
Trip mode choice Cost Travel Time
Assign trips by mode to specific transit lines and highway paths Cost Travel Time
SF-CHAMP Model Basics 9
Trips are aggregated
into “zones”
981 zones in San
Francisco
1,275 in other Bay Area
counties
Spatial Detail – Analysis Zones
SF-CHAMP Model Basics 10
Spatial Detail - Transit
Every transit stop
Every transit line
Every street
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SF-CHAMP – Roadway validation
EA AM MD PM EV0
5,000
10,000
15,000
20,000
25,000 Golden Gate Bridge - Southbound
Observed - SB Estimated - SBWeekday Time of Day
Flo
w
EA AM MD PM EV0
5,000
10,000
15,000
20,000
25,000 Golden Gate Bridge - Northbound
Observed - NB Estimated - NBWeekday Time of Day
Flo
w
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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SF-CHAMP – Roadway validation
EA AM MD PM EV0
10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 90,000
SF/SM County Line - Northbound
Observed - NB Estimated - NBWeekday Time of Day
Flo
w
EA AM MD PM EV0
10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 90,000
100,000 SF/SM County Line - Southbound
Observed - SB Estimated - SBWeekday Time of Day
Flo
w
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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SF-CHAMP – Roadway validation
EA AM MD PM EV0
10,000
20,000
30,000
40,000
50,000
60,000
70,000 Oakland Bay Bridge - Eastbound
Observed - EB Estimated - EBWeekday Time of Day
Flo
w
EA AM MD PM EV0
10,000
20,000
30,000
40,000
50,000
60,000
70,000 Oakland Bay Bridge - Westbound
Observed - WB Estimated - WBWeekday Time of Day
Flo
w
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SF-CHAMP – Roadway validation
Time of DayArea Type EA AM MD PM EV 24HR
0/1/2 1.330 0.969 1.041 1.035 1.009 1.0303 1.289 1.051 1.169 1.050 1.163 1.128
4/5 1.281 1.104 1.235 1.084 1.289 1.191All Locations 1.303 1.035 1.135 1.054 1.124 1.105
Time of DayVolume Classification EA AM MD PM EV 24HR
<40k 1.385 1.085 1.178 1.084 1.120 1.13540-80k 1.309 1.092 1.200 1.015 1.181 1.140>=80k 1.288 0.982 1.079 1.082 1.088 1.073
All Locations 1.303 1.035 1.135 1.054 1.124 1.105
Time of DayVolume Classification EA AM MD PM EV 24HR
<40k 0.218 0.090 0.116 0.077 0.143 0.10740-80k 0.097 0.050 0.067 0.045 0.083 0.057>=80k 0.129 0.048 0.047 0.069 0.067 0.050
All Locations 0.080 0.032 0.036 0.037 0.047 0.035
Estimated/Observed
Estimated/Observed
%RMSE
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SF-CHAMP – Transit validation
0
5,00
0
10,0
00
15,0
00
20,0
00
25,0
00
30,0
00
35,0
00
40,0
00
45,0
00
50,0
00
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
Daily Muni BoardingsModeled vs Observed
Muni BusesMuni Cable CarsMuni LRTy=x
Observed Boardings
Modele
d B
oard
ings
An additional tool in the toolbox - DTA
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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SF-CHAMP
Dynamic TrafficAssignment
TrafficMicrosimulation
Time-dependent user equilibriumwith realistic, but simplified vehicle simulation
Regional static user equilibriumactivity-based model
Highly realistic simulation of vehicle behavior and interactions
Northwest quadrant DTA network
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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200 Internal Zones60 External Zones3,000 Nodes7,000 Links240 Signals83 Transit Lines
How have we used DTA?
• Presidio Parkway Construction• Where do vehicles re-route when
intra-SF ramps are taken away on Doyle Drive?
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How have we used DTA?
• Geary Bus Rapid Transit• Where do vehicles re-route when we
take a lane away from Geary?• How do diversions affect other
streets?
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SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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25th
24th
23rd
22nd
21st
20th
19th
18th
17th
16th
15th
14th
Park
Pre
sidio
Funst
on
12th
11th
10th
9th
8th
7th
6th
5th
4th
3rd
2nd
Arg
uello
Palm
Jord
an/S
tanyan
C'n
wlt
h/B
'mont
Park
er
Spru
ceC
ook
Bla
ke
Collin
sW
ood
Em
ers
on
Maso
nic
Pre
sidio
Lyon
Baker/
St
Jose
phs
Bro
deri
ckD
ivis
adero
Sco
ttSte
iner
Fillm
ore
Webst
er
Laguna
Gough
-500
-400
-300
-200
-100
0
100
200
300
400
500
-2,500
-2,000
-1,500
-1,000
-500
0
500
1,000
1,500
2,000
2,500
2008 No Project - Geary Blvd - Westbound - Model Simulation
WB RT Off WB LT Off SB RT On NB LT On WB Through WB Mainline CountsWB Turn Counts - Mainline
Tu
rn V
olu
me
Main
lin
e V
olu
me
Issues that arose from current DTA use
• DTA represents ideal world network LOS knowledge• Drastic shifts away from main-line
roadways when their capacity reduced
• Hides potential congestion on Geary• Subarea reliant on demand from
external stations• Validation of individual turn movements
important• “Surgical Adjustments” still required• Reliant on centroid-connector
placement• Conflicting validation data
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SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
San Francisco’s Dynamic Traffic Assignment Model
Model Development Process
SFCTA DTA Model Peer Review Panel MeetingJuly 25th, 2012
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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Outline - Model Development Process
• Objectives for now versus the future• Overall Approach• DTA Package Selection• Project Tasks and Schedule
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DTA Model Development Objectives (for now)
• Have a working DTA model with results that make sense for the PM Peak period in San Francisco
• Have seamless process from SF-CHAMP to DTA results:• Little human intervention• Reduce human error• Use SF-CHAMP demand directly
• Behaviorally consistent• Allow SF-CHAMP to take advantage of
all fixes• Test having SF-CHAMP use DTA as it’s
network model
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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Left for “the Future”
• Rigorous validation for specific subareas
• Reconfiguring centroid loadings to be at parking
• Trip chaining and tours• Loading miiples from SF-CHAMP with
their individual characteristics• Influence of non-motorized travel on
traffic flow• 24 hour model; bigger subarea?• Assigning people to transit trips
• The future is now (FAST-TrIPs)
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DTA Model Development Approach
• Write code when possible for repeated human tasks :• Data format conversion• Network manipulation and validation
for DTA• Output validation and visualization
• Develop in an open source environment• Don’t re-write code that exists in our
DTA package• Make a counts database that interacts
with our network (CountDracula)
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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DTA Model Development Approach
• Use as much ‘real’ data as possible• Signal timings• Stop signs• Transit • Traffic flow parameters
• Fix all issues “at the source” if possible• Network geometry• Turn prohibitions• Demand (SF-CHAMP)
SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
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DTA Package Selection
• Evaluated alternatives that we knew about
• Selected Dynameq because:• Mature UI• Developer responsive with
development pathway• Detailed network representation:
• Lane-based delay• Transit vehicles and schedules explicit
• Was able to run• Results made sense when we tested
it
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Tasks and Schedule
Project ManagementModel Development
Tools Development
Application/Integration
Evaluation/Reporting
2011 2012A S O N D J F M A M J J A S O
Demand PreparationNetwork Preparation
Data PreparationModel Calibration
Network ConversionDemand Conversion
Signal ConversionTransit Conversion
Summary
Integration MemoApplications
Peer ReviewWebinar
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