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Network Assignment of Highway Truck Traffic in FAF3

Maks Alam, PEResearch LeaderBattelle

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Task Flow

Task #1Update the FAF

Network Link Attributes Data

Task 2Pre-Assign non-FAF

Traffic Counts

Task 3Truck Trips, Payload

and PCE Factors

Task 4FAF3 Assignments

Task 5FAF3 Forecast Year

Assignments

Task 6Documentation

Deliverable #1FAF3 Network

Deliverable #2FAF3 Network

with 2007 Assignments

Deliverable #3FAF3 Network

with 2040 Forecast

Assignments

Deliverable #4Technical Report

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Process Description

Task 1: Update FAF3 Highway Network

•Updating of the FAF3 network for NHS, Intermodal connectors, and urban by-pass other State specific sources for major highway realignment.

•Integration and updating of NN designation, NHS designation changes (up to-date March 2010), LCV network designation, state truck and hazmat route designation, state truck route restriction, limited bridge clearance

Task 2: Pre-Assigning non-FAF Traffic Counts to the FAF3 Network

• Integrate HPMS 2008 data with FAF3 network using a series of state specific route matching algorithms customized for each State.

• Develop algorithms to translate the HPMS traffic-flow information to the FAF network domain

• Calibrate state traffic flows and truck percentage at the state and urban boundaries

Task 3: Truck Trips, Payload and Passenger Car Equivalency Factors

•Revise FAF-2 algorithms and factors using the TEP project completed for FHWA in 2009.

•Update the conversion tools developed by Battelle during FAF-2 to reflect the new changes in FAF-3 zone and gateways system and the range of operation by truck classes

•Develop Truck based O-D matrix using the TEP and allocation of tonnage by truck classes.

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Process DescriptionTask 4: Assignment of FAF3 Flows to the Highway Network

•Develop and update FAF-2 link specific Impedance factors

•Develop and identify disaggregation network specific nodes to develop 123 by 123 OD matrix to 4609 by 4609 O-D matrix

•Develop disaggregation factors for domestic and international movements.

•Use TransCAD SUE traffic assignment with passenger volume as preloaded volume on the network

•Calibrate flow by adjusting initial link impedance, alpha, beta values, and disaggregation factors

•Use BPR delay functions

•Multiple trial and error iteration until FAF truck flows is comparable with the state truck flows develop in task 2

•Compare HPMS truck VMT with the FAF truck VMT for the base year 2007

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FAF Tonnages to Truck Conversion steps

04/21/23

Identify vehicle groups

Calculate TEF-National-Regional

Select major body types Calculate percent

distribution by vehicle group and body type

Calculate mean payloads by vehicle group and body type

Calibrate mean payloads (e.g. VTRIS weight data)

Analyze Regionalvariability

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Vehicle Groups

1. Straight trucks

2. Straight truck plus trailer

3. Tractor plus trailer

4. Tractor plus double trailers

5. Tractor plus triple trailers

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04/21/23

Major Body Types

• Platform (24.4%)

• Logging (2.1%)

• Tank (7.9%)

• Reefer (8.2%)

• Other (2.3%)

• Automobile (0.9%)

• Livestock (1.7%)

• Bulk (14.7%)

• Dry Van (37.7%)

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Conversion Algorithms

• Xi tons of commodity i carried by truck type Y j and body type k

= Xi βijk

• Number of truck type Yj and body type k to move

Xi βijk tons commodity i

= Xi βijk / ωijk

βijk = fraction of commodity i moved by truck type j with body type k

ωijk = mean payload of commodity i by truck type j body type k

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04/21/23

FAF3: Task 3 Truck Trips, Payload and PCE

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Conversion Algorithms -Continue

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FAF-3 Freight Travel Demand ModelFAF3 O-D (123 by 123 zones)

Trip Distribution

Impedance Function Calibration(Use FAF-2 base TLD)

DomesticInternational

Develop O-D Share

County-to-County FAF2

O-D Matrix

Disaggregation Techniques

Proportioning-Truck Volume- CBP -warehouse cluster

Logistical Impacts

Tri-Proportional Gravity Model Gamma (combined) FunctionModel Validity Test

Inflow/Outflow

FAF3

Network Assignment(SUE)

The dotted loop portion of the figure indicates that the process is iterative until a best possible solution is accomplished

Disaggregate by Domestic, Port and Border Crossings

Step 1

Step 2

Step 3

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Border Crossings Trip O-D nodes

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Inlands and Deep Water Trip O-D nodes

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FAF-3 Truck Trip O-D nodes

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Domestic Flow (Preliminary)