Driver behaviour assessment due to changes in the geometric layout to integrate lateral jet fans in long road tunnels

This driving simulation study is aimed at evaluating the effects on the longitudinal and transversal behaviour of drivers attributable to layout changes in an existing long tunnel caused by the introduction of jet fans along the tunnel walls. Furthermore, the effects of two different levels of light intensity capable of revealing or masking the presence of jet fans, thus manipulating the vision of participants, were also evaluated. Forty drivers were involved in this multi–level mixed-factorial experiment, in which twenty car and twenty truck drivers drove on three different layouts of a two–way two-lane long tunnel. Two different pairwise analyses were carried out to assess the effects of these two within-subject factors. The presence of oncoming traffic was also considered as a factor in the study. The presence of jet fans led to lower speeds and affected the transversal behaviour of car and truck drivers in different ways. In the presence of the jet fans trucks reduced the lateral distance to the tunnel wall, while car trajectories were always closer to it. All drivers showed better lateral control when facing the jet fans and when meeting oncoming vehicles. When the light intensity was reduced, truck drivers adopted lower speeds, while with higher light intensity they drove closer to the tunnel wall, thus reducing the risk of collision with any oncoming traffic.