The Argos Freight Modeling Project
Presentation to
SCAG Modeling Task Force
9/22/04
Genevieve Giuliano
Peter Gordon
School of Policy, Planning and Development
University of Southern California
The Argos Research Project
Purpose: Develop an intra-metropolitan freight flow model
using state of the art computer science techniques
Research Team
Jose-Luis Ambite
Sr. Research Scientist, ISI, USC
Genevieve Giuliano
Prof. Policy, Planning & Dev., USC
Peter Gordon
Prof. Pub Policy & Real Estate, USC
Qisheng Pan
Assoc. Prof., Urban Planning, TSU
LanLan Wang
PhD student, SPPD, USC
Matthew Weathers
PhD student, Computer Science, USC
Paul Pender
Naqeeb Abbasi
MPP student, SPPD, USC
MS student, Computer Science, USC
SPPD/ISI USC
Argos Project Goals
1. Contribute to knowledge in both information
science and social science
2. Address a significant government problem
3. Conduct interdisciplinary research that bridges
information science and social science
SPPD/ISI USC
The Intra-metropolitan Freight Flow
Estimation Problem
Models
– Goods movement as inter-regional trade problem
Many good models of inter-regional freight flows
High level of aggregation in geography, commodities
Don’t translate easily to intra-metropolitan context
– State-of-practice transportation planning models
Conventional urban models do not take freight directly into
account
Traditional 4-step approach difficult to apply to freight
– Differences in behavioral foundations of travel demand
– Variation in supply/demand across industry sectors
– Changing industry dynamics
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Problems, con’t
Data
– Extensive data requirements
Flows by mode, commodity, value, origin & destination
– Lack of disaggregate data
US, state level data generally available; county and smaller unit
limited
Fine geography does not coincide with fine sector data
– Proprietary data
Private firms not required to release data
Customs data processed by third parties
Black box nature
– Survey data
Infrequent, costly to update
SPPD/ISI USC
An Ideal Model Would…
…have solid behavioral foundation
…be multi-modal
…handle passenger and freight trip interactions
…minimize use of costly data
…be easily updated
…be transferable
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Our Approach
Use accessible, reliable data sources
–
–
–
–
Available to public
Regular updates
Transparent computations
Produced by reliable sources
Use economic supply/demand as model foundation
Use as much detail as possible
– Geography
– Economic sectors
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Basic Concepts of Model
Freight supply/demand in two basic categories
– Intra-regional – supply/demand within SCAG region
– Inter-regional – imports to, exports from, pass-through flows
Intra-regional supply/demand
– Use IMPLAN I/O model for region
– Factor out imports/exports
Inter-regional supply/demand
– Use import/export data sources (by mode)
– Identify import/export zones/nodes
Use regional employment as control total
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Main Data Sources
Item
Source
Comments
IMPLAN I/O
MIG, Inc
Commercially available, updated
annually, reliable
TAZ employment data by
sector
SCAG 2000 point
data
Emp totals < IMPLAN; adjust to
IMPLAN; updated infrequently
Waterborne
imports/exports
WCUS
Data are available online and
updated annually
Air imports/exports
LAX
Flows by sector only for LAX
Truck imports/exports
SCAG truck
surveys
“one-shot” surveys
Rail imports/exports
ITMS
Data not reliable
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IMPORTS/EXPORTS
INTRA-REGION
SCAG 2000
EMP
I-O TABLE
2001
AIRPORT DATA
WCUS
2000
AGGREGATE
SECTORS
ITMS
LINKS TO IMPORT,
EXPORT NODES
CONVERSION TO
COMPATIBLE SECTOR,
$/TON VALUES
ATTRACTIONS & PRODUCTIONS
($, JOBS, by TAZ)
SCAG
SURVEY
CHECK
COMBINE INTER AND INTRA P& A
CHECK
AGGREGATE TO REGIONAL TOTALS
GO TO TRANSPORTATION MODEL
FREIGHT FLOW MODEL:
STEPS IN GENERATING
FREIGHT
SUPPLY/DEMAND
SOME DETAILS ON INTRA-METRO PORTION
SCAG 2000 EMP DATA
IMPLAN 2001 I/O
Employment by sector,
TAZ
Regional transactions
table
Check/adjust
to sector,
county totals
Apply sector IO
coefficients to
employment data
Generate supply,
demand by TAZ,
sector in jobs, $$
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SOME DETAILS ON FREIGHT TRANSPORTATION MODEL
N x N matrix of freight P’s,
A’s in tons
Factor out
air, water,
rail
Generate O-D matrix using
gravity-type distribution model
Convert O-D flows
to PCEs
Traffic Assignment of
freight PCEs
SCAG region
transportation network
with equilibrium
passenger traffic
assignment
Equilibrium total traffic assignment
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Workflow for Freight Estimation
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Recent Work
Update data sources to 2000, 2001
Develop conversion table for sector codes (SIC,
NAICS, SITC, etc)
Seek better sources for ground imports/exports
Seek better methods for $$/tons/jobs
conversions
Develop logical internal checks
To learn more….http://www.isi.edu/~argos
SPPD/ISI USC