Test Methods for Evaluating Field Performance of RWIS Sensors

Abstract

Abstract for Part II: Field Test Procedures for Testing Environmental Sensor Stations. At least 42 state departments of transportation and other public and private sector agencies which use Road Weather Information Systems (RWISs) typically specify requirements for the accuracy of instruments at Environmental Sensor Stations (ESSs) at the time of procurement. These instruments include atmospheric and pavement surface and subsurface sensors. Most agencies rely on vendor-developed testing and calibration methods or they accept the sensor data without regular testing of calibration. This creates uncertainty in the accuracy of the data generated by the sensors and compromises the value of the information in decision making. As part of the National Cooperative Highway Research Program (NCHRP) it was determined that a need existed to develop guidelines for practical field testing of ESS sensors to evaluate if a sensor is providing an accurate representation of actual conditions at the installed site. The procedures contained in this document define the equipment and describe the procedures that state, county and city personnel can use to measure sensor parameters and evaluate sensors. The standardized methodologies for field testing various models of ESS pavement sensors were developed as a result of research performed under NCHRP Project 6-15, Testing and Calibration Methods for RWIS Sensors. Pavement temperature, surface state, and freezing point temperature are the three pavement sensor parameters that were addressed in the study. In order to develop these procedures, extensive laboratory and field tests were conducted, analyzed and documented. The basic approach of the process was a comparative test between baseline and pavement sensor data. Various potential field test procedures were developed and evaluated using a laboratory environment where external variables could be controlled and the tests could be repeatedly run. Based on these tests, a draft document of standard field test procedures was prepared. These draft field test procedures were then evaluated during on-site field testing in Minnesota, Nevada and Pennsylvania before being finalized for this document.