Getting Better Truck Flows and Loads: Truck Weight Case Study

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Florida has 20 years of experience in running continuous weigh-in-motion (WIM) stations and currently has 13 continuous WIM stations in operation. Therefore, an exhaustive investigation of the WIM data with the purpose of determining the optimum number of WIM sites to address the needs of pavement management systems was conducted by the Florida Department of Transportation for FHWA. The study was organized according to results of specific tasks (1 through 5). Under the early tasks the WIM data were examined for seasonal patterns or other patterns for allocating a continuous WIM station to a pattern group. Florida found little or no seasonal patterns. However, Florida has decided to divide the state into seven geographic areas for WIM data collection and analysis. The basic unit of analysis was the average equivalent single-axle load (ESAL) value per truck for a day at a site. Daily ESAL values are more variable than was originally thought. Florida found that 1 week (7 days) of data collection at stable sites, two 1-week collections at moderately stable sites at semiannual intervals and four 1-week collections at unstable sites spread over the quarters of a year were recommended. The last task investigated how many WIM sites should be conducted within Florida. These results should be helpful to other states conducting a WIM program.

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Transportation Research Record, v. 1435, p. 169-177