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Additional Long-Term Pavement Performance Studies


Seasonal Monitoring Program (SMP)

The SMP study attempts to understand the impact of daily, yearly, temperature, and moisture changes on pavement structure and its response to loads. Sixty-three sites were selected from the general pavement study (GPS) and specific pavement study (SPS) and are being monitored continuously for temperature and moisture. Measurements were made using the following devices:

  • Time-Domain Reflectometry – Subsurface moisture changes.
  • Thermistor Probes – Subsurface temperature changes.
  • Electrical Resistivity – Frost/thaw depth.
  • Piezometers – Ground water table determination.
  • Air Temperature Probes – Ambient temperature.
  • Tipping-Bucket Rain Gauge – Precipitation.


In addition, collection of deflection, profile, and distress data is being accomplished using Long-Term Pavement Performance (LTPP) equipment and testing protocols.

Information on instrumentation and data collection is contained in the report LTPP Seasonal Monitoring Program: Instrumentation Installation and Data Collection Guide, FHWA-RD-94-110, which can be obtained from the FHWA Product Distribution Center by emailing report.center@dot.gov, faxing 814–239–2156, or calling 814–239–1160.

For additional information, contact LTPP Customer Service Center, at 202–493–3035 or ltppinfo@dot.gov.

Dynamic Load Response Studies

Various portland cement concrete (PCC) pavement sections of the SPS-2 project in North Carolina were selected for measuring pavement response under controlled loading conditions. Both deflections and strains at defined positions within the slab were recorded under loading by known vehicles. A total of 30 traces were obtained from each pass of the loaded vehicle with multiple repetitions at multiple speeds collected at various times of the day. Data were collected quarterly over a two-year period. For additional information, contact LTPP Customer Service Center at 202–493–3035 or ltppinfo@dot.gov.



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