Development of a Transit Model Incorporating the Effects of Accessibility and Connectivity

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Development of a Transit Model Incorporating the
Effects of Accessibility and Connectivity
9th Conference on the Application of
Transportation Planning Methods Baton Rouge,
Louisiana April 6-10, 2003
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Research Team

• Ram M. Pendyala
• Dept of Civil Environmental Engineering, Univ
  of South Florida, Tampa
• Steve Polzin Xuehao Chu
• Center for Urban Trans Research (CUTR), Univ of
  South Florida, Tampa
• Seongsoon Yun
• Gannett Fleming, Inc., Tampa
• Fadi Nassar
• Keith Schnars PA, Fort Lauderdale
• Project Manager Ike Ubaka
• Public Transit Office, Florida Dept of
  Transportation, Tallahassee
• Programming Services Gannett Fleming, Inc.

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Outline

• Background
• History of transit model development in Florida
• BEST 3.0 Third generation transit model system
• Role of accessibility and connectivity
• BEST 3.0 methodology
• Accessibility/connectivity methodology
• Model development
• Data
• Estimation
• Application

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Background

• Transit systems planning and analysis
• Accessibility
• Availability
• Quality of Service
• Ridership
• Temporal Characteristics
• Transfers
• Route/Network Design
• Fare Policies and Structure
• Alternative Modal Options/Technologies/Route
  Types
• Disaggregate Stop-Level Analysis

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History of Transit Model Development

• FDOT Public Transit Office very proactive in
  transit planning tool development
• TLOS, FTIS, and INTDAS examples of transit
  planning and information tools
• Transit ridership modeling tools
• ITSUP Integrated Transit Demand Supply Model
• RTFAST Regional Transit Feasibility Analysis
  Simulation Tool
• Powerful stop-level ridership forecasting models

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Stop-Level Ridership Forecasting

• First generation ITSUP sensitive to demographic
  variables and frequency and fare of service
• Second generation RTFAST accounted also for
  network connectivity (destination possibilities)
• Desire transit ridership forecasting model that
  accurately accounts for accessibility/connectivity
  
• Third generation model called BEST 3.0
• Boardings Estimation and Simulation Tool

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BEST 3.0

• Model estimates number of boardings at stop by
• Route
• Direction
• Time period
• Model estimates two types of boardings
• Direct Boardings Walk and Bike Access
• Transfer Boardings Transit Access

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Separating Direct and Transfer Boardings

• Consider two types of stops, i.e., stops with no
  transfer possibility and transfer stops
• Estimate direct boardings model using data from
  non-transfer stops
• Apply direct boardings model to transfer stops to
  estimate direct boardings at transfer stops
• Subtract estimated direct boardings from total
  boardings to estimate transfer boardings
• Then estimate transfer boardings model

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Role of Accessibility and Connectivity

• Transit ridership strongly affected b y
• Destination accessibility
• Temporal availability
• Network connectivity
• Desire to have BEST 3.0 sensitive to all three
  aspects of transit accessibility
• Ability to test effects of alternative route and
  network design configurations on transit
  boardings
• Sophisticated methodology incorporated into BEST
  3.0

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BEST 3.0 Methodology

• s refers to stop on a route in a given direction
  and n refers to time period
• D direct boardings
• R number of bus runs
• B vector of buffer characteristics
• Oi vector of accessibility to characteristics
  of buffer areas for Hi stops, i 2, 3, 4, 5
• X vector of other route and stop characteristics

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BEST 3.0 Methodology

• T transfer boardings
• O1 vector of accessibility of boarding at H1
  stops during period n toward stop s
• Y vector of other route and stop
  characteristics
• Methodology thus includes both direct and
  transfer boardings equations
• Accessibility vectors play major role

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Definition of Stops

• Stops are defined with three pieces of
  information
• Physical location
• Route
• Direction
• Example 1
• 2 routes intersect
• Example 2
• 4 routes serve one location in the same direction

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Neighboring Stops

• N1 Neighboring stops along the same route
• N2 Stops along the same route but in the
  opposite direction that lead to different
  destinations providing the same opportunities.
• N3 Neighboring stops along other routes that
  lead to different destinations providing access
  to opportunities for the same activities.
• N4 Neighboring stops along other routes that
  lead to the same destinations. These routes may
  or may not share the same roads with the
  particular route in question

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Neighboring Stops (N1)

• N1 Neighboring stops along the same route

Stop in Question
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Neighboring Stops (N2)

• N2 Stops along the same route but in the
  opposite direction that lead to different
  destinations providing the same opportunities

Stop in Question
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Neighboring Stops (N3)

• N3 Neighboring stops along other routes that
  lead to different destinations providing access
  to opportunities for the same activities

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14
14
14
14
Stop in Question
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Neighboring Stops (N4)

• N4 Neighboring stops along other routes that
  lead to the same destinations these routes may
  or may not share the same roads with the
  particular route in question

Stop in Question
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Competing Routes/Stops

• Notion of neighboring stops effectively captures
  effects of competing routes/stops
• Riders may choose alternative stops, routes,
  destinations for pursuing activities
• Need to identify and define upstream and
  downstream stops that can be reached using
  neighboring stops
• Define series of stops, H1 through H5, identified
  by network connectivity

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Accessible Stops Illustration Network
1
2
4
3
Route 1
7
5
8
6
14
Route 2
14
14
14
10
11
12
9
Route 3
15
16
13
14
Route 4
Route 5
Route 7
Route 8
Route 6
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Neighboring Stops Illustration Network

• Network
• 8 routes (each two way)
• 16 nodes (n1, , 16)
• 64 stops (nX, n1,, 16 XN,S,E,W)
• Neighboring Stops
• N1 2S
• N2 6N
• N3 6W, 6E
• N4 6W, 6E

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Accessible Stops Illustration Network

• H1 1S, 1E, 2E, 2W, 3E, 3W, 3S, 4W, 4S, 5E, 7W,
  8W, 9N, 9E, 10W, 10E, 11W, 11E, 12N, 12W, 13N,
  13E, 14W, 14E, 15W, 15E, 16W, 16N
• H2 1W, 2N, 3E, 4E, 5S, 7S, 8S, 9S, 11S, 12S,
  13S, 15S, 16S
• H3 1N, 3N, 4N, 5N, 7N, 8N, 9W, 9N, 10S, 11E,
  11N, 12E, 12N, 13S, 13W, 14S, 15E, 15S, 16E, 16S
• H4 1N, 1W, 2E, 2W, 3N, 3E, 3W, 4E, 4N, 5W, 5N,
  7E, 8E, 9S, 10E, 10W, 11E, 11W, 12S, 12E, 13S,
  13W, 14E, 14W, 15E, 15S, 15W, 16S, 16E
• H5 1N, 1W, 3N, 3E, 3W, 4E, 4N, 5W, 5N, 7E, 8E,
  9S, 10E, 10W, 11E, 11W, 12S, 12E, 13S, 13W, 14E,
  14W, 15E, 15S, 15W, 16S, 16E

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Defining Accessible Stops

• H1 includes stops that can reach the N3 and N4
  neighboring stops (Interest boardings)
• H2 includes upstream stops that can be reached
  from the N2 stops (Interest buffer area)
• H3 includes stops downstream that can be reached
  from stop in question through route serving the
  stop in question via the transit network
  (Interest buffer area)
• H4 includes stops that can be reached from the N3
  and N4 neighboring stops (Interest buffer area)
• H5 includes stops in H4 that overlap with stops
  in H3 (Interest overlapped area)

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Computing Transit Accessibility

• Two components of transit accessibility
• Access/egress at stop in question
• Accessibility from stop to all other stops in
  network
• Access/egress at stop in question measured
  through simple air-distance buffer distance
• Accessibility from one stop to all other stops in
  network uses gravity-type measure

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Computing Transit Accessibility

• Oi is the measure(s) of accessibility included in
  the boarding equations
• Q represents buffer characteristics of stops in
  H2 through H5 and boardings at stops in H1
• G represents impedance from stops in H1 and
  impedance to stops in H2 through H5
• b is gravity model parameter
• Impedance measured by generalized cost of
  traveling from one stop to another

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Computing Impedance, G

• Components of impedance
• First wait time
• First boarding fare
• In-vehicle time
• Transfer wait time
• Number of transfers
• Transfer walking time
• Transfer fare
• Model sensitive to host of service characteristics

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Components of Impedance, G
Components
Unit
Value/Source
Symbol
Weight
Symbol
Value
First-wait time
Minutes
Half of first headway with a cap of 30
FWT
WFWT
3.0
First-boarding fare
Dollars
Base cash fare
FBF
WFBF
1/v
Minutes
Cumulative scheduled travel time
IVL
WIVL
1.0
In-vehicle-time
Minutes
TWT
WTWT
3.0
Transfer-wait time
Headway of transfer stop if no coordination and
deviation if coordinated for up to two transfers
Number of transfers
Number
Up to two
NTF
WNTF
5.0
Transfer-walking time
Minutes
Time to transfer stops at 3 mph
TWK
WTWK
1.5
Transfer-boarding fare
Dollars
Base cash fare for transfers
TBF
WTBF
1/v
v half of average hourly wage rate in service
area
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Model Functionality

• BEST 3.0 will retain user functionality from
  first two generations
• GIS interface for database setup and displays
• Sets of default equations by time period
• Automated buffering
• Automated accessibility and impedance
  computations
• Report generation including performance measures

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Model Development

• BEST 3.0 software development underway
• Model estimation using APC data from
  Jacksonville, Florida
• Using Census 2000 data for socio-economic
  variables
• Programming accessibility and impedance
  computation capability at this time
• Anticipated release of software in late summer or
  early fall

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Conclusions

• BEST 3.0 will provide a powerful framework for
  modeling transit ridership at stop level
• Incorporates effects of accessibility and
  connectivity on ridership
• Accessibility and impedance computations very
  sophisticated and accurate
• More precisely accommodates effects of service
  span and frequency (temporal aspects)
• Focus on ease of use and quick response capability