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Axle and Length Classification

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Axle and Length
  Classification

Steven Jessberger

Federal Highway Administration
2011 Highway Information Seminar


 

Presentation Acronyms

  • AASHTO – American Association of State Highway Transportation Officials
  • ASTM – American Society of Testing and Materials
  • AVC – Automatic Vehicle Classifier (class)
  • ATR – Automatic Traffic Recorder (volume)
  • DOW – Day of Week
  • FHWA – Federal Highway Administration
  • HPMS – Highway Performance Monitoring System
  • HVTIS – Heavy Vehicle Travel Information System
  • LTPP – Long Term Pavement Performance (SHRP)
  • MEPDG – Mechanistic Empirical Pavement Design Guide
  • NCHRP – National Cooperative Highway Research Program
  • OD – Origin and Destination
  • TMAS – Travel Monitoring Analysis System
  • TVT – Traffic Volume Trends
  • TMG – Traffic Monitoring Guide
  • UPACS – User Profile and Access Control System

 

Getting Results – 4 Steps

  • Construction of the site
  • Support/Maintenance
  • Processing of the data
  • Reporting of the Information

 

Class – 2001 TMG

  • Classification counts – why do them?
  • 25% – 30% of volume counts should be class
    • Coverage counts
    • Highway links
    • Annualized data
  • Length classification

 

Classification Counts

  • TMAS version 2.0 will accept all class data on a per site basis for each month.
  • TMAS 2.0 will replace the HVTIS in 2012
  • TMG formats for class data (C-card)
  • State specific axle class algorithm
    • Verify what you are using
    • Calibrate your classtree algorithms
    • LTPP classtree research

 

Axle Classtree Exercise Review

  • Why check your classification algorithm?
  • Why is it so important to make sure your classification data is accurate?
  • What can FHWA do to help?
  • Motorcycle array and helpful ideas to improve this type of data.

 

Axle Class Factoring

  • Factoring for Trucks
    • Variability by DOW and month of year
    • Improves reporting on trucks for:
      • HPMS
      • Freight Movements
      • Pavement Designs
  • Factoring for Motorcycles
    • Correct for the weekday portable counts
    • Correct for the month of year variance
    • Use processes and collection methods that correctly classifies motorcycles

 

Vehicle Length Class Data

  • Flexibility
  • Dual loops – last longer
  • Allows for non-intrusive technologies
    • Side fire technology
    • Over head technology
    • Under the road technology
  • All States are welcome to join the FHWA sponsored pooled funds
  • Test and verify your bins

 

Vehicle Length Class Data

  • Calibrate your sites
  • Test and verify your bins
    • Variances for length used in classes 2-3 bin 18’, 19.5’, 20’, 21’, 21.8’ and 22.5’ What do you use?
    • Example of possible bins:
      • Bin 1 class 1
      • Bin 2 classes 2-3
      • Bin 3 classes 4-7
      • Bin 4 classes 8-10
      • Bin 5 classes 11-13

 

Vehicle Length Class

Example of length class vs. axle class

Graph depicting vehicle length class - example of length class v. axle class

Axle Classification Vs. Length Classification

Vehicle Length (feet)

Classification avg length Std dev Vehicles
F01 5.38 2.23 25.00
F02 15.33 2.27 61,816.00
F03 18.32 4.13 14,541.00
F04 38.06 6.87 1,201.00
F05 25.14 4.91 1,231.00
F06 24.68 4.19 554.00
F07 31.58 2.86 11.00
F08 43.85 6.85 2,245.00
F09 64.51 5.69 24,327.00
F10 63.50 5.82 173.00
F11 68.76 2.62 757.00
F12 73.22 4.37 235.00
F13 69.02 5.74 17.00

Traffic Data Research

 

Research Documents

FHWA – Office of Policy Information

FHWA — Office of Policy Information Web Site — Research Documents

 

Research Documents

FHWA — Community of Practice

Research Documents — FHWA – Community of Practice

 

Standards

  • FHWA – Traffic Monitoring Guide
  • FHWA – HPMS Field Manual
  • ASTM documents related to classification counts
    • 1957-04 Installing & Using Pneumatic Tubes with Roadway Traffic Counters and Classifiers
    • 2300-06 Highway Traffic Monitoring Devices
    • 2415-05 Installing Piezoelectric Highway Traffic Sensors
    • 2467-05 Developing Axle Count Adjustment Factors
    • 2468-05 Metadata to Support Archived Data Management Systems
    • 2532-06 Evaluating Performance of Highway Traffic Monitoring Devices
  • AASHTO
    • Loop Detector Handbook 2006
    • Guidelines for Traffic Data Programs 2009
    • WIM Successful Practices 1997

 

MEPDG Required Class Inputs

  • Level 1 Design
    • Site specific class data (continuous or 4 seasons)
  • Level 2 Design
    • Regional class data (continuous or 4 seasons)
  • Level 3 Design
    • National class data (system defaults)

 

How to improve your class data?

  • Full width axle sensors (motorcycles)
    • road tubes
    • Piezo
  • Axle Sensors as primary sensor for class sites
  • Length can detect motorcycles as bin 1
  • More class sites for proper factoring
  • Class data QC (TMAS/LTPP/Pooled Fund)
  • Collect per vehicle format records (Idaho)
  • Calibrated your class algorithm(s) – 2011 State Survey
  • By lane class checks – done daily
  • Calibrate class sites annually

 

State/Vendor Best Practices

  • What practices have you experienced that others could benefit from?
  • What problems have you encountered that need to be dealt with?

 

Inductive Signature Technology

  • Axle class with loops only
  • Re-identification of vehicles
  • Calibration transfer between sites
  • Characteristics of Traffic Stream transfer between sites for:
    • OD studies – freight movement and loadings
    • Improved Pavement Designs
    • Travel Times
    • Model Inputs for Travel Patterns
    • Improved Safety

 

Questions??

FHWA – Headquarters

Office of Highway Policy Information
Travel Monitoring and Surveys Division
Washington D.C.

Steven Jessberger

202-366-5052
steven.jessberger@dot.gov