An important part of transportation asset management is inventory management of roadside infrastructure such as traffic signs. Developing and maintaining an inventory of roadside signs can support tracking of associated attributes such as measured retroreflectivity. Researchers in Vermont assessed an approach using passive radio frequency identification (RFID), a wireless tracking technology, for transportation signage management. The tested technology utilizes a reader to wirelessly read a radio frequency tag attached to, or embedded in, an object. In July 2019, this asset management system was tested on Vermont State Route 63 and on the University of Vermont (UVM) campus in Burlington. The testing process used a total of 32 RFID tags attached to traffic signs or guard rails and an RFID reader mounted on a survey vehicle. The system performed the RFID tag interrogation while researchers drove the survey vehicle past the signs during field tests, and the performance in successfully reading the tags was evaluated under varying configurations and speeds.
- Consider the limitations of the current passive RFID technology. Vermont Agency of Transportation had an expectation for a reader vehicle traveling at 50 mph speeds at a 60-foot distance to the sign. Based on the field tests, a 100 percent scan rate for passive RFID tags can only be achieved with a maximum of 35 mph and 30 feet between in-vehicle reader antenna and RFID tag. Scan rate at a higher driving speed and a farther distance will decrease the successful RFID tag read rate.
- Increase the number of antennas and use a combination of the circular and linear polarization antenna. Antenna configuration can achieve a higher percentage of tags read.
- Adjust default setting of RFID reader’s response time. This can increase reading performance when multiple antennas are used. By default, each antenna is allocated 1000 ms/scan reading time before another antenna is switched in. To optimize reading performance, this switching time was adjusted to 1 ms during the field test, the shortest value.