The Influence of Dynamic Signs on Cyclists’ Braking Rates: A Systematic Study Using Immersive Virtual Reality

Dynamic signs are signs that incorporate movement and are projected from a vehicle toward pedestrians or on the wall or floor of a public facility. Projection-based signage systems that are easy to install and move are becoming increasingly practical as a result of recent improvements in projector technology, and there is a need to accumulate knowledge on such signs and their interactions with people from an ergonomic perspective. This paper studies dynamic signs projected from parked cars (these signs warn that the car is about to reverse or open a door) with the goal to clarify the influence of these dynamic signs on the braking behavior of cyclists riding near the cars. In an experiment, we placed several parked cars in an immersive virtual reality space and created a system that allowed participants to move through the virtual space by steering a real bicycle. As participants rode past the row of parked cars, they took evasive actions to avoid a collision by actually operating the brake and handlebar in response to signs projected from cars warning that the car was about to reverse or open a door. For the experimental conditions, we looked at participant age groups, the method used to display the signs, and the timing of displaying the sign. The results suggest that the various experimental conditions produce different effects, and our discussion focuses on brake selection rates as a measure of cyclists’ responses to events.