U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590

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LTPP Precision and Bias Requirements for Weight Data - Specific Pavement Study (SPS) Traffic Pooled Fund Study


Pooled Fund Site 95 Percent Confidence
Limit of Error
Single Axles ± 20 percent
Axle Groups ± 15 percent
Gross Vehicle Weight ± 10 percent
Vehicle Speed ± 1 mph (2 kph)
Axle Spacing ± 0.5 ft. (150 mm)



Office of Infrastructure R&D Links

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» Infrastructure R&D Program
»Long-Term Bridge
  Performance Program

»Long-Term Pavement
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FHWA Pavement Links

» Design
» Construction
» Preservation
» Maintenance
» Management
» Rehabilitation


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Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
Turner-Fairbank Highway Research Center | 6300 Georgetown Pike | McLean, VA | 22101

All Federal Highway Administration (FHWA) information technology systems will be unavailable, Friday, October 28, at 10:00 p.m. to Sunday, October 30, at 11:59 p.m., EDT, while work is being performed on the network. During that time, users will not be able to access any FHWA systems.

If you have any questions or problems, please contact the 5-Help Service Center @ (866) 466-5221 or 5-HelpServiceCenter@dot.gov.