Autonomous measurements of bridge pier and abutment scour using motion-sensing radio transmitters.

Abstract

Two portable Radio Frequency IDentification (RFID) systems (made by Texas Instruments and HiTAG) were developed and tested for bridge scour monitoring by the Department of Civil and Environmental Engineering at the University of Iowa. Both systems consist of three similar components: 1) a passive cylindrical transponder of 2.2 cm in length (derived from transmitter/responder); 2) a low frequency reader (approx 134.2 kHz frequency); and 3) an antenna (of rectangular or hexagonal loop). The Texas Instruments system can only read one smart particle per time, while the HiTAG system was successfully modified here at University of Iowa by adding anti-collision feature. The HiTAG system was equipped with four antennas and could simultaneously detect 1,000 s of smart particles located in a close proximity. A computer code was written in C++ at the University of Iowa for the HiTAG system to allow simultaneous, multiple readouts of smart particles under different flow conditions. The code is written for Windows XP operational system which has a user-friendly windows interface that provides detailed information regarding the smart particle that includes: identification number, location (orientation in x, y, z), and the instance the particle was detected. These systems were examined within the context of this innovative research in order to identify the best suited RFID system for performing autonomous bridge scour monitoring. A comprehensive laboratory study that included 142 experimental runs and limited field testing was performed to test the code and determine the performance of each system in terms of transponder orientation, transponder