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Primary Topic: Pavement Data Collection
Description: The knowledge of traffic loads is a prerequisite for the pavement analysis process, especially for the development of load-related distress prediction models. Furthermore, the emerging mechanistically based pavement performance models and pavement design methods (such as the anticipated 2002 Pavement Design Guide) require the knowledge of the load spectra acting on the pavement during its lifespan.
This report describes a procedure for obtaining axle load spectra for Long-Term Pavement Performance (LTPP) sections. The procedure has been demonstrated and evaluated by applying it to 12 LTPP sections for which different amounts of monitoring traffic data were available. Typically, for the majority of LTPP sections, there are only a few years for which the traffic load data were collected by automated equipment in the mid-1990s. To obtain axle load spectra for all in-service years, traffic loads must be projected: backcasted (for the years before the installation of traffic monitoring equipment) and forecasted (for the years after the automated equipment no longer provides data).
This report also contains a review of the evolution of motor carrier technology (in terms of economical and political changes, regulatory changes in vehicle weights and dimensions, and engineering changes) and its impact on traffic loads, and a proposal to develop and use new summary statistical measures and tools for the management of load spectra. Major findings and recommendations include:
See also FHWA-RD-03-094, Estimating Cumulative Traffic Loads, Volume II: Traffic Data Assessment and Axle Load Projection for the Sites with Acceptable Axle Weight Data, Final Report for Phase 2.
FHWA Publication Number: FHWA-RD-00-054
Publication Year: 2000
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