Long-Term Field Study of Lightning Surges Through Traffic Monitoring In-Pavement Sensors

Proper protection of environmental sensors from lightning surges requires knowledge of the quantity and magnitude of lightning surges that may be experienced through the sensor. This effort involved the characterization of lightning surges propagating through the in-pavement sensors used for vehicle count and classification by the Florida Department of Transportation (FDOT). Field tests were conducted during the peak summer lightning months in central Florida from 2005 to 2014. Lightning surges were counted and the peak surge current determine for piezoelectric axle sensors and inductive loop presence detectors typically used in the FDOT's over 300 permanent telemetered traffic monitoring sites distributed over the highways in the State of Florida. These tests revealed that the lightning surges were numerous, complex and sometimes very large. From the results of these tests, the FDOT has replaced many of the SPDs used to protect their equipment from in-pavement sensor surges.