Traffic Monitoring Guide Truck Weight Monitoring Section 5
Traffic Monitoring Guide
Truck Weight MonitoringSection 5
Objective Identify Truck Weight Users Needs Describe Truck Weight Program Identify Data Collection Issues Describe Truck Weight Data
Reports
Pavement Design / Maintenance Bridge Design / Loading Enforcement Research Taxation & Administration Freight Planning
Data Users
Truck Weight Program Products Components Structure
Products Gross Vehicle Weights (GVW) Axle Load Distribution Equivalent Standard Axle Load
(ESAL) Day-of-Week and Seasonal
Patterns
ProductsRural Interstate Travel
by Vehicle Type (2001)
77
24 61
4
17
89
Traffic Volumes Equivalent 18,000 lb. Axle Load
0
20
40
60
80
100
Pe
rce
nt
COMPARISON OF GROWTH IN VOLUME AND LOADINGS ON THE INTERSTATE SYSTEM
70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 00 020
100
200
300
400
500
600
700
PE
RC
EN
T G
RO
WT
H (
3-Y
EA
R M
OV
ING
AV
ER
AG
E)
RURALAVERAGE DAILYLOAD
RURALAVERAGE DAILYTRAFFIC
YEARSource: Truck Weight Study and HPMS
Products
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
Structure of Vehicle Weight Program Continuous Count Program
Short Term Count Program
Continuous Count Program Purpose?
How many?
Locations?
Purpose Temporal distribution
Hourly Day-of-week Seasonal Direction
Axle adjustment factor Freight studies
How many? Supplement ATR program
Truck corridors
Short Term Count Program Purpose?
Segments?
Cycles?
Duration?
Factors?
Purpose? Spatial distribution (geographical)
Comprehensive
Foundation for AADTT
Axle adjustment factors
Segments? Homogeneous truck traffic section
Usually longer than volume segments Not always Between
Intersections Roadways Interchanges
Cycles? Quarterly Yearly 2 Years 3 Years (TMG) TMG (obsolescence )
Durations? 24 Hr 48 Hr (TMG) 72 Hr 7 - days
Types of Weighing Static Weighing Weight-in-Motion
Static Weighing Advantages
Accurate weight and dimensions Permanent scales
Disadvantages Time consuming Safe site Resource intensive
Picture of Static Weighing
Weigh-in-Motion (WIM) Advantages
More vehicle weighed Better coverage Unbiased sample
Disadvantages Higher installation costs Higher equipment and maintenance
costs Fixed locations
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
Picture of Load Cell WIM System
Picture of Bending Plate
WIM System
Picture of Piezo-CeramicWIM System
Picture of Capacitance MatWIM System
Picture of Capacitance Strip
WIM System
Picture of Bridge WIM System
With Strain Gauges
WIM Calibration Calibration Issues
Actual vs. WIM Test truck and random truck Auto-calibration and re-calibration
Front Axle Temperature
Reference Materials WIM Handbook ASTM WIM Standard Long Term Pavement Performance
Software and Reports Vehicle Travel information System
(VTRIS) Truck Weight Study (TWS)
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
VTRIS Products
System wide weight and ESAL’s values
Vehicle weight by vehicle class Weight distribution
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
Summary Truck weight User Needs Truck Weight Program WIM Issues Truck Weight Data Reports