140 likes | 261 Views
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.
E N D
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
Argos Project Goals • Contribute to knowledge in both information science and social science • Address a significant government problem • Conduct interdisciplinary research that bridges information science and social science
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
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
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
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
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
INTRA-REGION IMPORTS/EXPORTS WCUS 2000 SCAG SURVEY I-O TABLE 2001 AIRPORT DATA ITMS SCAG 2000 EMP LINKS TO IMPORT, EXPORT NODES AGGREGATE SECTORS CHECK CONVERSION TO COMPATIBLE SECTOR, $/TON VALUES ATTRACTIONS & PRODUCTIONS ($, JOBS, by TAZ) COMBINE INTER AND INTRA P& A FREIGHT FLOW MODEL: STEPS IN GENERATING FREIGHT SUPPLY/DEMAND CHECK AGGREGATE TO REGIONAL TOTALS GO TO TRANSPORTATION MODEL
SOME DETAILS ON INTRA-METRO PORTION SCAG 2000 EMP DATA Employment by sector, TAZ IMPLAN 2001 I/O Regional transactions table Check/adjust to sector, county totals Apply sector IO coefficients to employment data Generate supply, demand by TAZ, sector in jobs, $$
SOME DETAILS ON FREIGHT TRANSPORTATION MODEL N x N matrix of freight P’s, A’s in tons Factor out air, water, rail Generate O-D matrix using gravity-type distribution model SCAG region transportation network with equilibrium passenger traffic assignment Convert O-D flows to PCEs Traffic Assignment of freight PCEs Equilibrium total traffic assignment
Recent Work • Update data sources to 2000, 2001 • Develop conversion table for sector codes (SIC, NAICS, SITC, etc) • Seek better sources for ground imports/exports • Seek better methods for $$/tons/jobs conversions • Develop logical internal checks • To learn more….http://www.isi.edu/~argos