Minnesota DOT experience with animal warning systems.
The Minnesota DOT (Mn/DOT) installed an active deer warning system on a one-mile section of rural roadway. The system was found to be effective; however, shortly after the system was installed, technical issues associated with power supplies limited operations. Specifically, the solar power battery charging system used to energize beacon warning lamps (100 watt) and mechanical rotators could only last a few days without follow-up service calls. In addition, communications between detectors and beacons had to be hardwired which limited system flexibility. Mn/DOT, for example, wanted detectors to activate beacons on both sides of the roadway when deer were detected on one side, however, expensive under-roadway conduit would have to be installed.
In 2007, the system was redesigned to improve performance and flexibility. The new system used beam-type infrared detectors in 18 detection zones connected to 10 LED beacons (15 watt) using 900-Mhz wireless communications. System components were powered by solar rechargeable batteries having 300 percent more output and 350 percent more reserve capacity than the original system.
Park Rangers evaluated the effectiveness of the system by tracking the number of deer carcasses in the project area before and after the new system was activated in late April 2007.
Seven deer carcasses were observed in the project area from May through November of 2007 compared to 20 carcasses found during the same period in 2006. This represented a 65 percent reduction in deer-vehicle collisions. Researchers noted that the new system had less down time than the old system and this played an important role in the benefits observed. The older system was more susceptible to low sunlight and cold temperatures causing the system to become non-functional at times when the power draw was greater than the supply.