# The Car-Following Model and Its Applications in the V2X Environment: A Historical Review
## 3 Research on Car-Following Behavior in the V2X Environment
### Impacts of V2X Technology  
As an emerging technology, the system reliability, social acceptance, and especially the impacts after the application of V2X technology have received a large amount of attention  
Figure 2: Developing process of the traditional car-following models. from academics and people from all walks of life. With V2X technology, the informatization level of the transportation system has been significantly improved. Utilizing V2X technology, drivers can obtain massive amounts of traffic information, and parts of the information were hard to obtain in the past without V2X technology, which will influence the drivers to a certain extent. How and to what extent drivers will be affected are the questions that should be answered before the large-scale practical application of V2X technology. Based on the virtual driving experiment and Gipps model, the impacts of the Intelligent Speed Adaptation (ISA) system on drivers' car-following behavior and the key indicators restricting the system to exert this influence were explored by [PERSON] et al. [16]. The results suggest that the application of the ISA system will reduce the average velocity as well as maximum velocity in the car-following process, and the extents of this influence on various types of drivers are different. The field driving experiment was employed by [PERSON] et al. to study the impacts of the vehicle-to-infrastructure (V2I) system on the safety of the car-following process [17]. The results reveal that the V2I system can reduce the acceleration and deceleration deviations between different drivers and decrease the driver's delay. The results also suggest that these effects are deeper for the older driver. [PERSON] et al. explored the stare characteristics of the driver when he/she is driving a vehicle equipped with the Advanced Driving Assistance System (ADAS) in a car-following process [18]. The results show that the driver will stare more into the distance when using the ADAS. However, are these effects essentially to liberate the drivers from the heavy driving task and enter a relatively relaxing driving state, or to cause them to enter a distraction state? To explain this, [PERSON] et al. carried out a serial of virtual driving experiments, and the results suggest that the drivers who have used the ADAS before will find it easier to enter a distraction state [19]. The above works focus on the discussion of the impacts of V2X technology on driving safety in a car-following process, which could help us better design, deploy, utilize V2X technology to achieve the \"Re-evolution\" of the transportation system. The results can also provide a reference for modeling the car-following behavior in the V2X environment. However, more detailed discussion about the impacts of V2X technology on car-following behavior needs to be carried out. As mentioned above, when the driver accepts V2X technology and then utilizes it, a kind of human-machine interaction relationship is formed. With this relationship, the characteristics of driver's car-following behavior will differ from the past. [PERSON] et al. explored the characteristics of driver's car-following behavior with and without the V2X information [20]. The results suggest that the starting/braking process and fuel consumption and emission in the car-following process are optimized with V2X technology. Considering that V2X technology can help the driver react in advance with the information, [PERSON] et al. introduced a parameter into the Newell model [21] to represent this effect and, based on this, analyzed the positive impacts of V2X technology on car-following behavior [22]. Based on the virtual driving experiment, [PERSON] et al. explored the impacts of vehicle-to-vehicle (V2V) onboard devices on car-following behavior [23]. The results reveal that the V2V device has an obvious positive impact on car-following behavior, which is reflected in the indicators including the lasting time of steady-state, and the extent of this positive effect varies for different drivers.