Quantitative Indicator of Driving Risk Based on Improved Driving Safety Field

Existing literature suggests that accident rates in road tunnels are lower than those in open roads, but the accidents are considerably more severe and the rear-end collision is the most prevalent crash type in road tunnels. Compared with open roads, the driving behavior is affected by many external factors in tunnels, whereas the existing quantitative indicators of risk perception models are mainly generally based on information of the vehicle's state. In this study, we develop an improved driving safety field to describe the influence of driving risk caused by drivers, vehicles, roads, and changed environments on driving behavior. The improved driving safety field includes the following three parts: (i) potential field, which is by nonmoving objects on the roads, such as no-moving vehicles and speed limit signs; (ii) kinetic field, which is determined by the moving vehicles on roads; (iii) environment field, which is determined by the environmental factors, such as illuminance level and illuminance change rate. In addition, the field force acting on the vehicle is used to represent the vehicle's current risk. This research may help to develop control and management schemes to decrease the driving risk in tunnels.