Network Assignment of Highway Truck Traffic in FAF3 Maks Alam, PE Research Leader Battelle

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Network Assignment of Highway Truck Traffic
in FAF3Maks Alam, PEResearch LeaderBattelle
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Task Flow
Task 1 Update the FAF Network Link Attributes
Data
Deliverable 1 FAF3 Network
Task 2 Pre-Assign non-FAF Traffic Counts
Deliverable 2 FAF3 Network with 2007 Assignments
Task 3 Truck Trips, Payload and PCE Factors
Task 4 FAF3 Assignments
Deliverable 3 FAF3 Network with 2040 Forecast
Assignments
Task 5 FAF3 Forecast Year Assignments
Deliverable 4 Technical Report
Task 6 Documentation
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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 Description

• Task 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
Calibrate mean payloads (e.g. VTRIS weight data)
Analyze Regional variability
Identify vehicle groups
Calculate mean payloads by vehicle group and body
type

• Calculate TEF
• National
• Regional

Select major body types
Calculate percent distribution by vehicle group
and body type
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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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Major Body Types

• Logging (2.1)

• Dry Van (37.7)

• Platform (24.4)

• Livestock (1.7)

• Automobile (0.9)

• Bulk (14.7)

• Other (2.3)

• Reefer (8.2)

• Tank (7.9)

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Conversion Algorithms

• Xi tons of commodity i carried by truck type Yj
  and body type k
• Xi ßijk
• Number of truck type Yj and body type k to move
• Xi ßijk tons commodity i
• Xi ßijk / ?ijk
• ßijk fraction of commodity i moved by truck
  type j with body type k
• ?ijk mean payload of commodity i by truck type
  j body type k

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Conversion Algorithms -Continue
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FAF-3 Freight Travel Demand Model
FAF3 O-D (123 by 123 zones)
Disaggregation Techniques
Develop O-D Share
Proportioning -Truck Volume - CBP -warehouse
cluster
Step 1
Domestic International
Logistical Impacts
Trip Distribution
Tri-Proportional Gravity Model Gamma (combined)
Function
County-to-County FAF2 O-D Matrix
Model Validity Test
Inflow/Outflow
Step 2
Impedance Function Calibration (Use FAF-2 base
TLD)
The dotted loop portion of the figure indicates
that the process is iterative until a best
possible solution is accomplished
Step 3
Disaggregate by Domestic, Port and Border
Crossings
FAF3 Network Assignment (SUE)
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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)