Effects of the Driver's Disturbance Risk Preference Heterogeneity and its System Thresholds on Traffic Flow Instability

Driver's disturbance risk preference is defined as the driver's reaction degree to the disturbance, which is one kind of driver's attributes and can be expressed by the disturbance risk preference coefficient. This paper first attempts to investigate the effects of the driver's disturbance risk preference heterogeneity and its system thresholds on traffic flow instability based on a car-following model. An analytical analysis is conducted to obtain the calculation formulas of traffic system unstable threshold and traffic system instability eliminated threshold and traffic flow unstable region headway range, and the calculation method of the probability of traffic congestion caused by a small disturbance under some traffic scenarios, and then, the numerical analysis is carried out to present the main contributions and findings of this paper. It is shown that: 1) when the disturbance risk preference coefficient ratio between the preceding vehicle driver and the following vehicle driver is not less than the traffic system unstable threshold, the traffic flow is always unstable; 2) when the disturbance risk preference coefficient ratio between the preceding vehicle driver and the following vehicle driver is not bigger than the traffic system instability eliminated threshold, the traffic flow instability is completely eliminated; and 3) when the disturbance risk preference coefficient ratio between the preceding vehicle driver and the following vehicle driver is bigger than the traffic system instability eliminated threshold and less than the traffic system unstable threshold, such as for the general traffic situation, the smaller the coefficient ratio, the traffic flow instability is smaller, and vice versa.