## 3 Results
### Intelligent Vehicle Platoons Scenario Experiment
#### 3.2.2 Desired Headway of Intelligent Vehicles  
The key factor in the operation of intelligent vehicles is the desired headway between vehicles. Under the condition of a platoon size \(N\) set to 2, the desired headways of both the ACC and CACC vehicles were varied to investigate their impact on carbon emissions. 1. Impact of desired headway of ACC vehicles on traffic flow carbon emissions. Maintaining the desired headway of the CACC vehicles (\(t_{c}\)) at 0.6, the desired headway of the ACC vehicles was set to 1.1 s, 1.6 s, and 2.2 s, respectively. The simulation results show the carbon emission variation curves for each condition in Figure 8.  
Figure 7: Impact of different sizes of electric vehicle fleets. In Figure 8, it can be observed that under all conditions, road carbon emissions decreased as the infiltration rate (P) of intelligent vehicles increased, which is consistent with previous research findings. Additionally, as the desired headway of the ACC vehicles increased, the downward trend of the carbon emissions curve became less steep. The curves can be divided by P = 24%, where for \(p\) values lower than this threshold, the road carbon emissions reach a low value at a larger ACC desired headway of 2.2 s. Conversely, for \(p\) values greater than the threshold, the emissions reach a low value at a smaller desired headway of 1.6 s. This indicates that the optimal desired headway for achieving low carbon emissions varies with different infiltration rates of intelligent vehicles, and a specific analysis based on the specific situation is required. The adjustment of the \"Ta\" parameter is anticipated to yield a considerable influence on the ensuing behavioral paradigms displayed by intelligent vehicles. When confronted with scenarios marked by a sparser distribution of intelligent vehicles, the rationale for maintaining a more substantial interval between these pioneering vehicles and their conventional counterparts becomes readily apparent. Such a strategy confers the latter with an extended response window, efficaciously tempering assertive driving behaviors, including abrupt accelerations or decelerations. Conversely, within contexts characterized by a denser presence of intelligent vehicles, the inter-vehicle communication facilitated through onboard systems endows meticulous control over diminished trailing distances. This strategic arrangement augments the seamless and expedited flow of traffic, thereby culminating in a palpable reduction in carbon emissions along the thoroughfare. 2. Impact of desired headway of CACC vehicles on traffic flow carbon emissions. Compared to the desired headway at 1.1 s, the desired headway of CACC vehicles was varied as 0.6 s, 0.9 s, and 1.1 s, respectively. The carbon emission variation curves for each condition are shown in Figure 9.  
In Figure 9, it can be observed that the carbon emissions curves under different conditions are more closely packed together. This indicates that the desired headway for CACC vehicles has a limited overall impact on the road carbon emissions. However, at tc = 1.1 s, the overall carbon emissions are generally higher. For \(p\) values below 30%, the desired headway (\(t_{c}\) = 0.9 s) results in lower carbon emissions, whereas for \(p\) values above 30%, the desired headway ((\(t_{c}\) = 0.6 s) leads to lower carbon emissions. Therefore, it can be concluded that the optimal desired headway of CACC vehicles for achieving low carbon emissions varies with the different infiltration rates of intelligent vehicles, and changing (\(t_{c}\) does not have a significant effect. Figure 8: Impact of different desired headway settings in ACC. The adjustment of the \"\(t_{c}\)\" parameter has a significant impact on the behavior of intelligent vehicle formations. When there are few intelligent vehicles on the road, a small gap between vehicles can lead to more aggressive driving behaviors among conventional vehicles.