overview freight modeling overview tianjia tang, pe., ph.d fhwa, office of freight management and...

OverviewOverviewFreight ModelingFreight Modeling

OverviewOverviewFreight ModelingFreight Modeling

Tianjia Tang, PE., Ph.D

FHWA, Office of Freight Management and [email protected]

Phone: 202-366-2217

www.fmip.gov www.fmip.gov

www.ops.fhwa.dot.gov/freightwww.ops.fhwa.dot.gov/freight

For more information on freight modeling…

1: Modeling Objective2: Modeling Approach3: Method Classification4: Challenges5: Summary

Presentation OutlinePresentation OutlinePresentation OutlinePresentation Outline

Three main areas:1: Economic development2: Logistic and supply chain3: Transportation planning

and engineering

Modeling ObjectiveModeling ObjectiveModeling ObjectiveModeling Objective


Private Business, Local, Regional, State, and Federal Government perform modeling for…

Private Business, Local, Regional, State, and Federal Government perform modeling for…

Three main areas:1: Economic development2: Logistic and supply chain3: Transportation planning

and engineering

Based on the most recent TRB survey, freight modeling has been used to analyze…

1: Program level issues2: Project level issues


Program level:

1) Long Range Plan and Transportation Improvement Plan

2) Conformity3) Size and weight issues4) Modal diversion issue5) Others


Project level:

1) Bridge/roadway design 2) Corridor study3) Modal diversion4) Weight station/parking

optimization5) Hazmat6) Others


1) … amount of freight goes into my jurisdiction


Bottom Line …

1) … amount of freight goes into my jurisdiction2) … amount of freight goes out my jurisdiction


Bottom Line …

1) … amount of freight goes into my jurisdiction2) … amount of freight goes out my jurisdiction3) … amount of freight gets moved within my

jurisdiction


Bottom Line …


jurisdiction4) … amount of freight goes through my

jurisdiction


Bottom Line …


jurisdiction4) … amount of freight goes through my

jurisdiction5) … ways/methods these freights get moved


Bottom Line …

Time-line:Time-line:

PresenPresentt

PastPast

FutureFuture


04/20/23 … … Know the Know the

target !target !… … Know the Know the

target !target !


Modeling ApproachModeling ApproachModeling ApproachModeling Approach

… simulating behavior … mechanistic based flow… empirical constructed…

… simulating behavior … mechanistic based flow… empirical constructed…

…given the long history, knowledge, and experiences on passenger demand travel modeling…

Modeling ApproachModeling ApproachModeling ApproachModeling Approach

…simulating behavior … mechanistic based flow and empirical constructed

…given the long history on passenger demand travel modeling…

1: Production2: Distribution3: Mode4: Assignment

1: Production2: Distribution3: Mode4: Assignment

1: Commodity based2: Trip generation rate based3: Empirical statistical approach4: Trend analysis

Method ClassificationMethod ClassificationMethod ClassificationMethod Classification

Criteria: unique to freight models as compared with urban passenger models

Commodity Based Method Commodity Based Method Commodity Based Method Commodity Based Method

Commodity Production

($/Tonnage)

Commodity Distribution

$/Tonnage

Commodity Mode Split $/Tonnage

Vehicle Trip Generation

Traffic Traffic AssignmentAssignment

Commodity Based Modeling Method Commodity Based Modeling Method Commodity Based Modeling Method Commodity Based Modeling Method


($/Tonnage)

1: To estimate the production and consumption of

2: Units of measure: tonnage and $ a given commodity



($/Tonnage)

…establish a base model/equation relating the production of a specific commodity to economic activities such as economic growth, employment, et al.

…establish a base model/equation relating the production of a specific commodity to economic activities such as economic growth, employment, et al.



($/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…



($/Tonnage)


$/Tonnage






$/Tonnage


($/Tonnage)


($/Tonnage)

Commodity Consumption

($/Tonnage)


($/Tonnage)



$/Tonnage


($/Tonnage)


($/Tonnage)

Commodity Specific

Origin-Destination Data

Commodity Specific

Origin-Destination Data



$/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…



$/Tonnage

CFS OD Methods … loglinear, ipf…

area # 1 2 3 4 5 6 71 25 36 21 7 12 0 82 4 41 28 73 2 12 22 2 5 84 5 24 12 215 6 33 61 0 56 12 45 64 35 24 0

Production

Consumption



$/Tonnage

CPC Methods – gravity model …area # Production Consumption

1 25 362 4 413 2 124 5 5 6 336 12 457 08 219 25 2210 1 211 9 812 6 613 12 14



($/Tonnage)


$/Tonnage





Rail Freight: STB’s annual waybill Rail Freight: STB’s annual waybill


Water Freight: US ACOE annual S-S OD Water Freight: US ACOE annual S-S OD

Truck Freight: most complicated Truck Freight: most complicated

Mode split data: Past, Current, and Future? Mode split data: Past, Current, and Future?


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!




($/Tonnage)


$/Tonnage





Tonnage data are converted to # of truck loads

Tonnage data are converted to # of truck loads


Data Sources used for conversion

1: Vehicle Inventory and Use Surveyhttp://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


Methods to Convert Tonnage to Truck Loads

Methods to Convert Tonnage to Truck Loads

http://www.census.gov/svsd/www/02vehinv.html

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



($/Tonnage)


$/Tonnage





1: all or nothing 2: stochastic user equilibrium 3: user equilibrium 4: capacity restrained 5:

system optimum 6:others

1: all or nothing 2: stochastic user equilibrium 3: user equilibrium 4: capacity restrained 5:

system optimum 6:others


Uniqueness of Freight Transport …the logistic industry

urban routing

Uniqueness of Freight Transport …the logistic industry

urban routing


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…


More than a dozen states or MPOs developed their freight models based

on the commodity approach

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

For more specific state model information, visit links provided at:

www.fmip.gov

Trip Generation Rate Trip Generation Rate Based Based Trip Generation Rate Trip Generation Rate Based Based

Trip Production

Trip Distribution



Trip Production

# of truck trips generated per land use/employment/other

activities…

# of truck trips generated per land use/employment/other

activities…


Gravity model Spatial intervention

others

Gravity model Spatial intervention

others

Trip Distribution



1: all or nothing 2: stochastic user

equilibrium 3: user equilibrium

4: capacity restrained 5: system optimum

6:others

1: all or nothing 2: stochastic user

equilibrium 3: user equilibrium

4: capacity restrained 5: system optimum

6:others


Strength

Availability of field count data …

Strength

Availability of field count data …

Weakness

Multimodal issue and forecasting issue …

Weakness

Multimodal issue and forecasting issue …

Empirical Statistical Methods Empirical Statistical Methods Empirical Statistical Methods Empirical Statistical Methods

Completely different from the traditional 4 – steps modelingCompletely different from the traditional 4 – steps modeling

Number of vehicles N = f(land use, business locations, and other information)


Dependent Variable N= Observed Dependent Variable N= Observed Traffic count number Traffic count number

Independent VariablesIndependent Variables

Function classification of the roadway, Function classification of the roadway, adjacent land use type, major business adjacent land use type, major business

distance ….distance ….

Strength

Availability of truck count data …

Strength

Availability of truck count data …

Weakness

forecasting issue …

Weakness

forecasting issue …


Trend Analysis Trend Analysis Trend Analysis 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…

By examining the past traffic count data, and making linear extrapolation of the data to obtain future data… more on a

project level…AADT Vs. Calendar Year

45000

47500

50000

52500

55000

57500

60000

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Calendar year

AA

DT

ChallengesChallengesChallengesChallenges

1: Modeling objective

2: Relationships between GDP and shipments

3: Economic sensitive modal data/model

4: Integration with other models

Big Picture

ChallengesChallengesChallengesChallenges

1: Effective and efficient data collection methods

2: Freight distribution algorithm

3: Freight traffic assignment algorithm

4: Model calibration and validation

Technical

SummarySummarySummarySummary

1: Objective

2: Approach

3: Types of Freight Models

4: Challenges

That’s All. Thank You!That’s All. Thank You!That’s All. Thank You!That’s All. Thank You!

overview freight modeling overview tianjia tang, pe., ph.d fhwa, office of freight management and...

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