Background About 4000 reindeer die each year in traffic, causing significant costs. This study investigated the acceptability of a real-time reindeer warning service and its potential impacts on driver behaviour, foresight and traffic safety.

Methods Professional heavy goods vehicle drivers participating in the field test on two main roads in Northern Finland received real time warnings based on sightings of reindeer on or near the road. The information was provided by the same group of drivers and a group of reindeer herders.

The warning system was a simple smart phone application and was designed to be easy to use. When a driver saw reindeer near the road, he touched a circle on the screen of a smart phone installed in their vehicle, sending the warning to all nearby drivers using the application. The warnings were in effect within an area of radius 500 m from the initial warning for the following 2–4 hours.

Results The impacts of the service were evaluated by driver questionnaires and interviews. The drivers were interviewed twice, after about 6 and 12 months use of the service. 23 drivers participated in the interviews. In addition, also driving companies, reindeer herders and other stakeholders and experts were interviewed. The majority of drivers assessed the service useful. They especially liked the possibility to foresee unexpected situations. Drivers valued service simplicity. It was estimated that, if installed in every vehicle, the service could lead to a decrease in reindeer accidents by 9.7–17.8%, corresponding to a reduction of 395–725 accidents annually. Regarding all injury accidents in the area, the service was estimated to cause a reduction of 0.76–1.52% corresponding to 2–4 injury accidents annually.

Conclusions The service worked well and was well received by its users. The results of the trial were promising.