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TPF-5 (004), Long-Term Pavement Performance (LTPP) Specific Pavement Study (SPS) Traffic Data Collection


The traffic pooled fund study is designed to fill in gaps and improve the quality and quantity of monitored traffic data from the LTPP program's SPS-1, -2, -5, -6, and -8 projects.

More information is available at the Transportation Pooled Fund Study website.

Participating States
Map of the United States highlighting the participating States: Alabama, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Kansas, Maryland, Michigan, Mississippi, New Mexico, New York, North Carolina, Ohio, Pennsylvania, and Texas.

A core objective of the LTPP SPS studies is to understand and quantify the relationship between pavement performance, truck volumes, and axle loadings. The objective of this pooled fund study is to improve the quality and increase the quantity of monitored traffic data (volumes, classifications, and weights) at the SPS-1, -2, -5, -6, and -8 test sites. There are a total of 64 SPS-1, -2, -5, and -6 test sites and 20 SPS-8 sites throughout North America.

This multi-year study will attempt to collect research quality data by installing a Bending Plate, Load Cell, or Quartz Sensor at as many of these SPS sites as economically possible. For the purpose of this study, research quality data is defined to be at least 210 days of data (in a year) of known calibration meeting LTPP's precision requirements for steering and tandem axles, gross vehicle weight, vehicle length (bumper-to-bumper), vehicle speed, and axle spacing.

This pooled fund study has two phases that run concurrently. Phase I consists of performing annual field calibrations and validations of Weigh-in-Motion (WIM) systems according to LTPP field procedures. All WIM systems must meet LTPP's precision requirements for steering and tandem axles, gross vehicle weight, vehicle length (bumper-to-bumper), vehicle speed, and axle spacing. Phase II consists of maintaining WIM systems installed by the Phase II contractor and performing daily downloads and verification checks of the data from these systems.

The Phase II contractor is only responsible for maintaining and verifying the data from the systems they install under this project. Any WIM system installed by the highway agency using their in-house staff must be maintained by the highway agency. However, the Phase I contractor will perform the annual field calibrations and validations for all SPS WIM systems that are part of this study.

State highway agencies and industry representatives still have the opportunity to join the pooled-fund study. To learn more, contact Deborah Walker at FHWA, 202-493-3068 (email:


More information about the study is available below:



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