This study was conducted on the Canadian Pacific main line railway, which bisects the Bow River valley within Banff National Park, Alberta in the Canadian Rocky Mountains. Several dozen train-animal collisions occur annually in this area.
The warning system comprised of four types of self-contained electronic devices connected through a wireless radio-frequency network, which were termed train detectors, warning devices, camera controllers, and signal repeaters. These devices were deployed along the railway track to coordinate the activation of warning signals and cameras (for observing animal responses) with the arrival of a train. A warning time of 30 ± 5 seconds was targeted, in contrast to previous work that targeted 20 ± 5 seconds, based on the desire to ensure that conditioned (warning) stimuli were typically presented to animals before unconditioned (train) stimuli.
At each site, a test zone was designated for the study, consisting of a 200-meter straight length of track exiting a curve, where trains were more likely to be obscured by vegetation and topography. Train detectors were mounted on the track 40 seconds away at previously measured mean train speed in both directions from the test zone center. When a train moving towards the test zone passed a detector, this device sent a radio signal to all other devices in the network. This signal was received by camera controllers (two per site) mounted in trees on either side of the test zone, where they triggered trail cameras facing the test zone to take 90 photographs at up to two frames per second, yielding at least 45 seconds of footage. The radio signal was also received by warning devices (four per site) within the test zone, which emitted the warning signals (flashing amber lights and bell sounds) after a 10 seconds delay for a period of 35 seconds (30 seconds before and 5 seconds after train arrival at the test zone center). Signal repeaters were placed as needed (one to four per site) between the train detectors and camera controllers to ensure network connectivity. All devices were programmed to wait six minutes after an activation while the train passed.
- Wildlife warning systems have the potential to reduce train-animal collisions, as shown by an increase in animal flight initiation times in response to warnings. The results from the system testing warrant efforts to further quantify actual collision reductions. However, the sampling effort required to measure collisions directly, as compared to flight initiation times, would be substantial. Advances in computer vision and energy management could lower the cost of evaluation.
- Future implementations of this warning system may benefit from increased warning time. Animals in 13 treatment sequences (which were excluded from the analysis) began to flee before the warning devices were expected to emit signals. Two other large animals (also excluded) appeared to interrupt or delay their retreat from the train to look directly towards the warning devices. An increase in warning time to 35 or 40 seconds might have allowed the activation of warning signals to precede the flight responses of all observed animals. However, the time between warning activation and train arrival must remain short enough that learning can occur.
- Warning systems like the studied design could be implemented as a cost-effective alternative or as a complement to exclusion fencing.
Volume 87, October 2020