FHWA > Policy > Office of Highway Policy Information > HSS > Presentations

Slide 1

Traffic Monitoring Guide
Truck Weight Monitoring
(Section 5)

Powerpoint presentation (2964 KB)

Slide 2

Objective

• Identify Truck Weight Users Needs
• Describe Truck Weight Program
• Identify Data Collection Issues
• Describe Truck Weight Data Reports

Slide 3

Data Users

• Pavement Design / Maintenance
• Bridge Design / Loading
• Enforcement
• Research
• Taxation & Administration
• Freight Planning

Slide 4

Truck Weight Program

• Products
• Components
• Structure

Slide 5

Products

• Gross Vehicle Weights (GVW)
• quivalent Standard Axle Load (ESAL)
• Day-of-Week and Seasonal Patterns

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Slide 8

Truck Weight Program Components

• Users Needs
  • End in Mind
  • 2002 Pavement Design Guide
• Resources
  • Federal-aid and construction funds
  • Locations
• Available funds
  • Truck Weight Groups
  • Criteria for groups

Slide 9

Structure of Weight Vehicle Program

• Continuous Count Program
• Short Term Count Program

Slide 10

Continous Count Program

• Purpose?
• How many?
• Locations?

Slide 11

Purpose

• Temporal distribution
• Hourly
• Day-of-week
• Seasonal
• Direction
• Axle adjustment factor
• Freight studies

Slide 12

How many?

• Supplement ATR program
• Truck corridors

Slide 13

Short Term Count Program

• Purpose?
• Segments?
• Cycles?
• Duration?
• Factors?

Slide 14

Purpose?

• Spatial distribution (geographical)
• Comprehensive
• Foundation for AADTT
• Axle adjustment factors

Slide 15

Segments

• Homogeneous truck traffic section
• Usually longer than volume segments
• Not always Between
• Intersections
• Roadways
• Interchanges

Slide 16

Cycles?

• Quarterly
• Yearly
• 2 Years
• 3 Years (TMG)
• TMG (obsolescence )

Slide 17

Durations?

• 24 Hr
• 48 Hr (TMG)
• 72 Hr
• 7 - days

Slide 18

Types of Weighing

• Static Weighing
• Weight-in-Motion

Slide 19

Static Weighing

• Advantages
  • Accurate weight and dimensions
  • Permanent scales
• Disadvantages
  • Time consuming
  • Safe site
• Resource intensive

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• Advantages
  • More vehicle weighed
  • Better coverage
  • Unbiased sample
• Disadvantages
  • Higher installation costs
  • Higher equipment and maintenance costs
  • Fixed locations

Slide 22

WIM Sensor Technology

• " Load Cell" . Hydraulic load cells
• "Bending Plates" . Strain gauge load cells
• "Piezo" . Piezo-electric cables / film / quartz
• Fiber Optics
• Capacitance mats / pads / strips
• Strain gauges on bridge beams

Slide 23

Picture of Load Cell

Slide 24

Picture of Bending Plate WIM System

Slide 25

Picture of Piezo-Ceramic WIM System

Slide 26

Picture of Capacitance Mat WIM System

Slide 27

Picture of Capacitance Strip WIM System

Slide 28

Picture of Bridge WIM System With Strain Gauges

Slide 29

WIM Calibration

• Calibration Issues
  • Actual vs. WIM
  • Test truck and random truck
  • Auto-calibration and re-calibration
    • Front Axle
    • Temperature
  .

Slide 30

Reference Materials

• WIM Handbook
• ASTM WIM Standard
• Long Term Pavement Performance

Slide 31

Software and Reports

• Vehicle Travel information System (VTRIS)
• Truck Weight Study (TWS)

Slide 32

VTRIS (Vehicle Travel Information System)

• Windows-based System
  • FoxPro data base (DBF)
• Data Base Management System
  • Load / Validate
  • Generate summary file
  • Produce W-Tables
  • Archive and ship data

Slide 33

VTRIS

• Products
  • System wide weight and ESAL's values
  • Vehicle weight by vehicle class
  • Weight distribution

Slide 34

W-Tables(TWS)

• W1-Weigh Station Characteristics
• W2-Comparison of Weighted vs. Counted
• W3-Average Empty, Loaded, and Cargo Weights
• W4-Equivalency Factors
• W5-Gross Vehicle Weights
• W6-Overweight Vehicle Report
• W7-Distribution of Overweight Vehicles

VTRIS Reports: http://apps.fhwa.dot.gov/vtris/vtris.aspx

Slide 35

Summary

• Truck weight User Needs
• Truck Weight Program
• WIM Issues
• Truck Weight Data Reports