A virtual reality evacuation experiment on driving behavior in reduced visibility

Highlights Two visual effects attributed to visibility: loss of contrast and loss of detail. Smoke and fog density affected headway during driving in virtual reality. Some participants followed the lead vehicle while others lagged behind. Limitations of virtual reality could have an impact on driving behavior. Abstract Understanding human behavior during wildfire evacuations helps to improve the emergency management response. Virtual reality allows to simulate wildfire scenarios that would be challenging or unsafe to recreate in the real-world. Few studies have examined the impact of poor visibility conditions due to smoke on individual and aggregate driving behavior during a wildfire evacuation. This paper presents two studies conducted in virtual reality to better understand the effect of reduced visibility on headway (distance between vehicles). The first study, a pilot study involving 20 participants, investigated how smoke affects visibility using a head-mounted display. Participants’ task involved reading out loud the speed limit on a traffic sign placed along the road (no driving required). The results revealed two visual effects that could be attributed to visibility in the virtual environment: the loss of contrast and the loss of detail. Following the pilot study, a driving study involving 51 participants was conducted to examine the impact of lighting conditions (day/night), atmospheric conditions (smoke/fog), and varying density levels of smoke/fog on driving behavior. Participants drove in one atmospheric condition (smoke or fog) during daytime and nighttime through all density levels (random order). The results show that smoke and fog density affected distance headway.