Travel Demand Forecasting Model - Council of Fresno County ...

The Fresno COG
Travel Demand Forecasting Model
“How the Pieces Fit Together”
Mike Bitner PE, Senior Transportation Planner
Council of Fresno County Governments
The Fresno COG Travel Demand Forecasting Model
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COG Modeling Staff
Mike Bitner
Kathy Chung Kristine Cai Lindsey Monge
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What is Ahead
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• Gain a basic understanding
of travel demand
forecasting.
• Understand model Input &
assumptions
• Recognize model steps
• Appreciate model limitations
• Use Model output
What’s s Ahead
(Objective)
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Types of Models
n Fashion Models
n Trend Analysis (Growth(
Factor
Growth Factor)
– 3.5% annual growth on road
n Simulation
– Individual vehicle movements
n Travel Demand Model
– Fresno COG Model
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What is a Travel Demand Model?
A systematic process for
translating land use and
transportation supply into
projections of future travel
demand.
Travel Demand Models
estimate the amount of
travel on the
transportation system.
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Planning Tool!
Not Perfect
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Model Users
n Cities
n County
n Caltrans
n Private Consultants
n Developers
n COG
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Use of the Model
n
n
n
n
n
Analyzing General Plans
Traffic Impacts of Development
Corridor Studies
Evaluating Traffic Mitigation
Measures
Evaluating Emissions Impacts
for Transportation Conformity
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Putting the Puzzle
n Network
n Traffic Analysis Zone
n Land Use
Together
n 4 Step Modeling Process
–Trip Generation
–Trip Distribution
–Mode Split
–Traffic Assignment
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Putting the Puzzle
n Network
Together
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Transportation Network
n Network
– Based on adopted
general plans
– Replicates
freeways,
expressways,
arterials and
collectors – existing
& future
– Local roads not
generally modeled
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Network Development
Network Development
Using County GIS Street File
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Links and Link Attributes
n Nodes
n Name
n Distance
n Facility Type
n Lanes
n Speed
n Project ID
n Improvement
Year
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Nodes
n May represent
intersections or
other decision
points
n Nodes are
described by
coordinates for
location
purposes
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Putting the Puzzle
Together
n Network
n Traffic Analysis Zone
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Urban Traffic
Zones
The basic
geographical unit
for distributing
population and
Employment
within a study
area.
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Rural
Traffic
Analysis
Zones
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Traffic Analysis Zones
Zone Data
Households
– Single & multiple
family
Employment
– Retail
– Service
– Government
– Education
– Other
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Putting the Puzzle
Together
n Network
n Traffic Analysis Zone
n Land Use
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Land Use
Housing
Employment
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Housing
n Single Family Households
– O Autos
– 1 Auto
– 2+ Autos
n Multiple Family Households
– 0 Autos
– 1 Auto
– 2+ Autos
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Land Use Inputs- Housing
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Employment
nEmployment
– Retail
– Service
– Government
– Education
– Other
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Land Use Inputs Employment
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Resources
Base Year (Starting Point)
n Census Data
n Census Transportation
Planning Package
(CTPP)
n Dunn and Bradstreet
n Employment
Development
Department (EDD)
n Local Surveys
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Resources
Future Year
nGeneral plans
nPopulation
projections
nTiming of
development
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Population Forecasts
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Putting the Puzzle
n Network
n Traffic Analysis Zone
n Land Use
Together
n 4 Step Modeling Process
–Trip Generation
–Trip Distribution
–Mode Split
–Traffic Assignment
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Four-Step Modeling
Process
n Trip Generation
– How many trips occur in
each zone?
n Trip Distribution
– How many trips travel from
one zone to any other
zone?
n Mode Choice
– What travel modes do they
use?
n Trip Assignment
– Trips from one zone to
another are assigned to
travel routes.
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Trip Generation
Step 1
nEstimates the
Number of Trips
that a Household
or Business Will
Produce or Attract
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Trip Generation
nTrips are divided into 5
trip purposes
– Home-Work
– Home-Shopping
– Home-Other
– Work-Other
– Non-Home Based
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;
IF (AREATYPE1.1) ; mountains
P[1]=P[1]+1.00*0.85 * ( 0.53*SF_0+0.89*SF_1+2.06*SF_2) ; H-W
P[1]=P[1]+1.00*0.85 * ( 0.56*MF_0+0.94*MF_1+2.18*MF_2) ; H-W
P[2]=P[2]+1.20*0.85 * ( 0.55*SF_0+1.02*SF_1+1.25*SF_2) ; H-S
P[2]=P[2]+1.20*0.85 * ( 0.47*MF_0+0.88*MF_1+1.08*MF_2) ; H-S
P[3]=P[3]+1.00*0.85 * ( 1.22*SF_0+2.97*SF_1+4.69*SF_2) ; H-O
P[3]=P[3]+1.00*0.85 * ( 0.82*MF_0+2.21*MF_1+3.60*MF_2) ; H-O
P[5]=P[5]+1.00*0.85 * ( 0.55*SF_0+0.55*SF_1+0.55*SF_2) ; O-O
P[5]=P[5]+1.00*0.85 * ( 0.40*MF_0+0.40*MF_1+0.40*MF_2) ; O-O
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Trip Distribution
“Gravity Model”
Step 2 Step 2
The process of
determining trip
exchanges or the
number of trips
between each pair of
zones
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Mode Choice
Step 3
n Walk
n Bicycle
n Motorcycle
n Auto
n Bus
n Train
n Plane
n Ferry
n Subway
n Space Shuttle
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Trip Assignment
Step 4
nPredicts Preferred
Routes that Trips
will Take
nResults in Traffic
Forecasts
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Calibration/Validation
n Calibrate with Base
Year Survey Data
n Validate with Base
Year Traffic Counts
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Validation by Facility
Type
Facility Percent RMSE
Type Target Target
Freeway +/- 7% 15%
Rural Highway +/- 10% 40%
Rural Road +/- 15% 40%
Expressway +/- 10% 40%
Urban Arterial +/- 15% 40%
Collector +/- 25% 50%
Overall 35%
Source: FHWA: Calibration & Adjustment of System Planning Models, 1990
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Validation by Volume Group
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Validation by Screenlines
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The Model is Run
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Limitations of Travel Models
n Only as good as the inputs
n Cannot predict changes in
land use or attitudes
n Average weekday model
n Travel occurs only on the
network – No off road
n Only as good as the inputs
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Loaded Network
Daily Volume
AM Peak Hour
PM Peak Hour
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Select Link
Analysis
Able to determine
the origin and
destination of all
traffic that
crosses the
“selected roadway
section”.
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Select Link
Analysis
Separately assigns
volumes that cross
the “selected” link.
Able to determine
the origin and
destination of all
traffic that crosses
the “selected link”.
Output available in
table format
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Selected zone
volume TAZ
Total roadway volume
Select Zone Analysis
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Select Zone
Analysis
Tracks volume
from a single
“selected” zone
to all other
zones.
Also available
in table format.
Excellent for
use in TIS
analysis.
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Select Zone Analysis
Tracks volume from
a single “selected”
zone to all other
zones.
Also available in
table format.
Excellent for use in
TIS analysis.
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Select Zone Analysis
Selected zone volume only
Total roadway volume
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Provides
link analysis
by zone
districts
District 1 = Fresno
District 2 = Clovis
District 3 = County
Zone Compression
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Zone Compression
Provides link analysis by zone districts.
District 1 = City of Fresno
District 2 = City of Clovis
District 3 = County of Clovis
Etc.
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The Fresno COG
Travel Demand Forecasting Model
Additional information available on our website at
www.fresnocog.org
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The End
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