Narrow Results

In this paper, we study the effect of randomization probability p on the fundamental diagrams of the Nagel–Schreckenberg model (NS) with "slow-to-start" rule introduced by Benjamin, Johnson and Hui (BJH). It is shown that this model exhibits metastable states (which leads to the occurrence of hysteresis) only for very low values of the randomization probability (p≤0.08). Here we propose a simple generalization of the BJH model by introducing a distance-dependent randomization. With such simple generalization, the hysteresis effect and phase separation exist for all values of randomization probability. The new fundamental diagrams are analyzed within the framework of the distributions of time and distance headways.

The correlation between the velocity of two successive vehicles as a function of time headway is studied in the one-dimensional cellular automata (CA) NaSch model within parallel dynamic update. It is found that a strong correlation occurs in short time headway. The behavior of the correlation velocity as a function of the car density in different traffic states is also investigated. Moreover, our study is also extended to a more complicated situation where the two vehicles are separated by a number n of other vehicles. It is shown that the velocity correlation coefficient depends strongly on the number n of vehicles in between and on their positions.

As the road conditions deteriorate during the period of ice and snow in the cold region, the probability of traffic accident increases. The prediction method presented in this research proves to anticipate the trend of traffic accidents, and provide a reference for traffic management. By adopting time headway as determination for conflicts, and number of conflicts as determination for traffic accident. Thresholds of conflict time were calculated based on the result on the field study for driving speed and pavement friction coefficient during the period of ice and snow in the cold region. In this paper, based on the data of urban arterial sections in Harbin, China, a model is developed to capture the interrelation between traffic volume and number of conflicts. By combining the relationship between traffic conflict and traffic accident, this model can further prove the interrelation between traffic volume and the number of accidents. Hence, this paper presented a method for determining the relation between number of traffic accidents and traffic volume during the period of ice and snow in the cold region.