Continued Field Testing and Refinement of Novel Water and Ice Sensor Systems on Bridge Decks - FY12 NATSRL

Project summary:

This project seeks to continue field testing low-cost sensing systems for monitoring ice and water on bridge deck surfaces. These sensing systems are based on the measurement of the dielectric response of the sensor in contact with or close proximity to ice, water, or aqueous solutions of deicing chemicals. The study uses time domain reflectometry, which probes the physical state of precipitation and deicing chemicals on the deck or road surface (via dielectric relaxation) using low-cost sensors.

During Phases III and IV of this project, it was determined that the physical attributes of the prototypes developed during the earlier work were inappropriate for bridge deck installations. MnDOT engineers required that they be planar and not require drainage through the deck. As RWIS platforms had been widely deployed on decks throughout the state, the researchers decided to adhere to the RWIS geometric format. This necessitated a significant re-engineering of the sensor hardware before installation and testing at remote bridge sites could proceed. To that end, extensive development of a robust sensor meeting these requirements was developed and tested without compromise to the earlier performance results. In large part the maintenance of performance was achieved through a significant modification of the software to include Wavelet analysis of the raw data in determining the surface state of the sensor platform (ice vs. air vs. water vs. electrolyte present on the sensing electrode structure). The combined regression results for raw TDR responses treated by three analysis procedures are shown to give rise to very reliable results. Unfortunately, remote field testing of sensors installed on bridge decks was not accomplished.