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Overview Freight Modeling Overview Tianjia Tang, PE., Ph.D FHWA, Office of Freight Management and Operations Tianjia.Tang@FHWA.DOT.GOV Phone: 202-366-2217
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www.fmip.govwww.ops.fhwa.dot.gov/freight For more information on freight modeling…
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1: Modeling Objective 2: Modeling Approach 3: Method Classification 4: Challenges 5: Summary Presentation Outline
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Three main areas: 1: Economic development 2: Logistic and supply chain 3: Transportation planning and engineering Modeling Objective
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Private Business, Local, Regional, State, and Federal Government perform modeling for… Three main areas: 1: Economic development 2: Logistic and supply chain 3: Transportation planning and engineering
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Modeling Objective Private Business, Local, Regional, State, and Federal Government perform modeling for… Three main areas: 1: Economic development 2: Logistic and supply chain 3: Transportation planning and engineering
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Based on the most recent TRB survey, freight modeling has been used to analyze… 1: Program level issues 2: Project level issues Modeling Objective
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Program level: 1)Long Range Plan and Transportation Improvement Plan 2)Conformity 3) Size and weight issues 4)Modal diversion issue 5)Others Modeling Objective
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Project level: 1)Bridge/roadway design 2) Corridor study 3)Modal diversion 4)Weight station/parking optimization 5)Hazmat 6)Others Modeling Objective
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1)… amount of freight goes into my jurisdiction Modeling Objective Bottom Line …
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1)… amount of freight goes into my jurisdiction 2)… amount of freight goes out my jurisdiction Modeling Objective Bottom Line …
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1)… amount of freight goes into my jurisdiction 2)… amount of freight goes out my jurisdiction 3)… amount of freight gets moved within my jurisdiction Modeling Objective Bottom Line …
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1)… amount of freight goes into my jurisdiction 2)… amount of freight goes out my jurisdiction 3)… amount of freight gets moved within my jurisdiction 4) … amount of freight goes through my jurisdiction Modeling Objective Bottom Line …
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1)… amount of freight goes into my jurisdiction 2)… amount of freight goes out my jurisdiction 3)… amount of freight gets moved within my jurisdiction 4) … amount of freight goes through my jurisdiction 5) … ways/methods these freights get moved Modeling Objective Bottom Line …
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Time-line: 4 Present 4 Past 4 Future Modeling Objective
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… Know the target ! Modeling Objective
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Modeling Approach … simulating behavior … mechanistic based flow… empirical constructed… …given the long history, knowledge, and experiences on passenger demand travel modeling…
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Modeling Approach …simulating behavior … mechanistic based flow and empirical constructed …given the long history on passenger demand travel modeling… 1: Production 2: Distribution 3: Mode 4: Assignment 1: Production 2: Distribution 3: Mode 4: Assignment
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1: Commodity based 2: Trip generation rate based 3: Empirical statistical approach 4: Trend analysis Method Classification Criteria: unique to freight models as compared with urban passenger models
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Commodity Based Method Commodity Production ($/Tonnage) Commodity Distribution $/Tonnage Commodity Mode Split $/Tonnage Vehicle Trip Generation Traffic Assignment
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Commodity Based Modeling Method Commodity Production ($/Tonnage) 1: To estimate the production and consumption of 2: Units of measure: tonnage and $ a given commodity
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Commodity Based Modeling Method Commodity Production ($/Tonnage) …establish a base model/equation relating the production of a specific commodity to economic activities such as economic growth, employment, et al.
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Commodity Based Modeling Method Commodity Production ($/Tonnage) Three Key Issues: 1: Commodity classification 2: Geographic level (size of the geographic area) 3: Economic activities: population, employment, payroll… Three Key Issues: 1: Commodity classification 2: Geographic level (size of the geographic area) 3: Economic activities: population, employment, payroll…
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Commodity Based Modeling Method Commodity Production ($/Tonnage) Commodity Distribution $/Tonnage Commodity Mode Split $/Tonnage Vehicle Trip Generation Traffic Assignment
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Commodity Based Modeling Method Commodity Distribution $/Tonnage Commodity Production ($/Tonnage) Commodity Consumption ($/Tonnage)
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Commodity Based Modeling Method Commodity Distribution $/Tonnage Commodity Production ($/Tonnage) Commodity Consumption ($/Tonnage) Commodity Specific Origin-Destination Data Commodity Specific Origin-Destination Data
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Commodity Based Modeling Method Commodity Distribution $/Tonnage Methods in OD Data Development 1: Commodity Flow Survey: Gap Filling, disagregation, … 2: Gravity Model: single constrained, double constrained, spatial interaction… 1: Commodity Flow Survey: Gap Filling, disagregation, … 2: Gravity Model: single constrained, double constrained, spatial interaction…
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Commodity Based Modeling Method Commodity Distribution $/Tonnage CFS OD Methods … loglinear, ipf…
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Commodity Based Modeling Method Commodity Distribution $/Tonnage CPC Methods – gravity model …
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Commodity Based Modeling Method Commodity Production ($/Tonnage) Commodity Distribution $/Tonnage Commodity Mode Split $/Tonnage Vehicle Trip Generation Traffic Assignment
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Commodity Based Modeling Method Rail Freight: STB’s annual waybill Commodity Mode Split $/Tonnage Water Freight: US ACOE annual S-S OD Truck Freight: most complicated Mode split data: Past, Current, and Future?
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Commodity Based Modeling Method Rail Freight: STB’s annual waybill Water Freight: US ACOE annual S-S OD Truck Freight: most complicated Mode split data: Past and Current ? Future? For a given commodity, Modal share typically remains unchanged! Commodity Mode Split $/Tonnage
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Commodity Based Modeling Method Commodity Production ($/Tonnage) Commodity Distribution $/Tonnage Commodity Mode Split $/Tonnage Vehicle Trip Generation Traffic Assignment
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Commodity Based Modeling Method Tonnage data are converted to # of truck loads Tonnage data are converted to # of truck loads Vehicle Trip Generation
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Data Sources used for conversion 1: Vehicle Inventory and Use Survey http://www.census.gov/svsd/www/02vehinv.html 2: Examples of State and local data http://www.scag.ca.gov/goodsmove/pdf/truckcnt_rpt.pdf http://www.sfta.wsu.edu/index.htm http://www.sfta.wsu.edu/presentation/pdf/6_steeringCommitteJune13.pdf Commodity Based Modeling Method Methods to Convert Tonnage to Truck Loads Methods to Convert Tonnage to Truck Loads
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Commodity Based Modeling Method Commodity Production ($/Tonnage) Commodity Distribution $/Tonnage Commodity Mode Split $/Tonnage Vehicle Trip Generation Traffic Assignment
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Commodity Based Modeling Method 1: all or nothing2: stochastic user equilibrium 3: user equilibrium 4: capacity restrained 5: system optimum 6:others Traffic Assignment Uniqueness of Freight Transport … the logistic industry urban routing
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Commodity Based Modeling Method Strength Based on fundamental economic activities… Strength Based on fundamental economic activities… Weakness Exceedingly hard to validate and calibrate… Weakness Exceedingly hard to validate and calibrate…
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Commodity Based Modeling Method More than a dozen states or MPOs developed their freight models based on the commodity approach For more specific state model information, visit links provided at: www.fmip.gov
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Trip Generation Rate Based Trip Production Trip Distribution Traffic Assignment
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Trip Generation Rate Based Trip Production # of truck trips generated per land use/employment/other activities…
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Trip Generation Rate Based Gravity model Spatial intervention others Trip Distribution
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Trip Generation Rate Based Traffic Assignment 1: all or nothing 2: stochastic user equilibrium 3: user equilibrium 4: capacity restrained 5: system optimum 6:others
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Trip Generation Rate Based Strength Availability of field count data … Strength Availability of field count data … Weakness Multimodal issue and forecasting issue … Weakness Multimodal issue and forecasting issue …
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Empirical Statistical Methods Completely different from the traditional 4 – steps modeling Number of vehicles N = f(land use, business locations, and other information)
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Empirical Statistical Methods Dependent Variable N= Observed Traffic count number Independent Variables Function classification of the roadway, adjacent land use type, major business distance ….
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Strength Availability of truck count data … Strength Availability of truck count data … Weakness forecasting issue … Weakness forecasting issue … Empirical Statistical Methods
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Trend Analysis By examining the past traffic count data, and making linear extrapolation of the data to obtain future data… more on a project level…
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ChallengesChallenges 1: Modeling objective 2: Relationships between GDP and shipments 3: Economic sensitive modal data/model 4: Integration with other models Big Picture
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ChallengesChallenges 1: Effective and efficient data collection methods 2: Freight distribution algorithm 3: Freight traffic assignment algorithm 4: Model calibration and validation Technical
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SummarySummary 1: Objective 2: Approach 3: Types of Freight Models 4: Challenges
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That’s All. Thank You!
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