Animal Vehicle Crash Mitigation Using Advanced Technology Phase I: Review, Design and Implementation
This report compiled data from several evaluation studies that examined the impacts of animal warning systems in the Unites States and Europe. In Montana and Pennsylvania, data related to planning, installation, reliability, and acceptance testing were evaluated to assess technical performance. Additional research, examining historical data collected from other sites (worldwide) was used to construct a hypothetical benefit-cost model and determine the benefits needed to justify system costs.
Overview of Animal Detection Systems and Evaluation Results
Data collected from previous reports, Internet resources, media, and interviews with transportation agencies and industry were used to identify the main characteristics of animal warning systems. Overall, researchers identified 34 animal detection systems. As of February 2006, 5 sites in North America and 15 sites in Europe were operating; many others had been retired or dismantled.
In general, two types of detection systems were identified: "area-cover" systems that use microwave sensor or infrared heat detection technology; and "break-the-beam" systems that use microwave, infrared, or laser beam technology. Other strategies, such as tagging animals with radio transmitter collars and installing roadside receivers to detect large herds have also been implemented. At the roadside, warning signs with LED lights or flashing beacons and roadway illumination systems have been installed. Most warning systems reset automatically; others have been equipped with wireless communications for remote management. To check system reliability, roadside cameras have been installed to monitor system performance. In areas where access to the power grid is not practical, solar power and batteries have been used.
Detailed data were provided for seven animal warning systems in Switzerland where passive infrared sensors were used to detect deer (1993-1996). Sensors were installed at each site creating a 20-30 meter wide detection zone that ranged from 50-200 meters in length depending on site conditions. Once an animal was detected, LED signs with a deer symbol were activated to alert approaching drivers. Once activated, the warning lights remained on for 45 seconds. Five (5) of the sites also had an LED sign with an enforceable maximum speed limit of 40 km/h (25 mi/h).
Data collected before and after the deployment indicated that animal detection systems can reduce ungulate-vehicle collisions by as much as 81-82 percent. All seven sites had fewer collisions. Three of the seven sites did not have a single collision 6-7 years after installation.
Experimental Deployment of Animal Warning Systems in Montana and Pennsylvania
Montana (MT), Yellowstone National Park. The MT system was based on a "break-the-beam" principle. Low power microwave radio signals (around 35.5 GHz) were used to detect large animals in a coverage area of about one mile alongside US-91 between mile marker 28 and 29. When an animal’s body interrupted the signal between a transmitter and receiver, flashers on the closest three static messages were activated for a minimum of three minutes with a max continuous operation of 12 minutes. Overall the system was designed with 15 detection zones (6 on the east side and 9 on the west side).
Overall, researchers indicated that the MT system was able to detect large animals reliably. Patterns in the detection data showed no indication of system failures or abundant false detections. The system had a median number of 47 detections per day and a median detection interval of 1 min 33 sec indicating the total time that the flashing warning lights would be activated was 1 hr 13 min per day. Compared to permanently activated warning signs which tend to be ignored by drivers, researchers indicated that real-time activation of warning lights after a detection event could potentially lead to increased driver response.
Pennsylvania (PA): Thompsontown (Northwest of Harrisburg). The PA system used microwave sensors (10.525 GHz) to detect the movement of large animals. If animal movement within the detection zone of sensor exceeded threshold values (1-2 seconds of sustained movement) the system activated warning flashers on static message signs for at least three minutes or until no new detections occurred. Overall the system had 17 pole stations, each with two sensors (9 along the westbound lanes and 8 along the eastbound lanes). The coverage area included about 0.5 mile alongside Highway 22/322.
In general, the PA system suffered from a range of technological challenges. The system was able to detect elk but, had problems detecting humans (a model for deer) during reliability testing.
Cost-Benefit Analysis of a Hypothetical Deployment
The potential benefits and costs associated with the installation and use of an animal detection system were calculated. The calculations were based on an analysis of a hypothetical system deployed on a one mile section of roadway.
The Results of the cost-benefit analysis suggested that the benefits of animal detection systems are greater than the costs at locations that have an average of at least five deer-, three elk-, or two moose- vehicle collisions per mile road length per year.