## 5 Behavioral Analysis
### Example  
This segment shows an example of a behavioral pattern where none of the vehicles took any evasive action. The speed, time until collision T\({}_{2}\) and GT profiles of both vehicles were estimated using extracted trajectories. Figure 3, given below, depicts the interaction trend between two two-wheelers at a right angle, along with the profiles of the indicators in Figure 4.  
Figure 3: Interaction between two two-wheeler. The following interaction occurred between two two-wheelers (labelled in a green and yellow box) and is individually determined as a risky case. The entire interaction phase was initiated from the point P1 when the vehicle V1 (green box) observed the approaching vehicle V2 (yellow box); at point P2, the second vehicle V2 shows up in the range of assessment. Meanwhile, the vehicles managed to maintain a high speed. The T2 reduced until it attained the minimum value at P3 as both the vehicles approached the possible conflict point. The GT, which permits a whole vehicle to cross through the possible conflict point, also decreased after a 0.5 s lag and attained its lowest  
Figure 4: T2, GT and below Speed profiles. value between \(\mathrm{P_{3}}\) and \(\mathrm{P_{4}}\). \(\mathrm{V_{1}}\) crossed the possible conflict point just before the second vehicle reached \(\mathrm{P_{4}}\), indicating interaction completion, whereas at \(\mathrm{P_{5}}\), both the vehicles crossed the conflict point. In the research sites, various categories of vehicles were observed, such as two-wheelers, cars, auto rickshaws, buses, light motor vehicles, e-rickshaws, etc. Among the total traffic observed at all sites, the major vehicle categories were two-wheelers, cars and auto rickshaws, comprising approximately 95 percent of the total traffic. Hence, only these categories were used to conduct the subsequent detailed analysis in order to obtain unbiased results. Figure 5, below, shows sample graphs of pair wise vehicle-vehicle interactions, plotted to analyze the pattern and to determine if there is any notable difference in the indicators' profile with the changing vehicle categories. Road user behavior was classified into two categories according to the indicators' profile shape and the presence of evasive action. The details of both categories are as follows:  
1. **Non-Aggressive interaction**: When one or both vehicles take any evasive action, it can be categorized into receptive road user behavior (non-aggressive behavior). Upon analyzing the \(\mathrm{T_{2}}\) and GT profiles in Figure 5a, it is apparent that the vehicle interaction with various other vehicle categories generates a similar profile shape. The minimum values for both \(\mathrm{T_{2}}\) and GT occur towards the middle or end of the interactive process. The GT value starts to drop as two vehicles get closer to a potential conflict point until it hits its lowest value, which is close to zero, signalling that the two are most likely to arrive at the conflict point simultaneously. However, because of evasive action taken by the road user, the gap time started to increase again. The lowest value of GT can therefore be described as a risky point. In Figure 5a, when the speed profiles of different interactions were analyzed, it was observed that the speed profiles decreased over time. And, once it reached the minimum value, it started to increase again, indicating that one or both road users had taken significant measures to avoid a potential collision. Therefore, this behavior can be classified as a non-aggressive interaction as it involves an evasive action. 2. **Aggressive interaction**: In this type of interaction, it was observed that despite having low values for \(\mathrm{T_{2}}\) and GT, neither of the road users took any evasive action. As can be seen in the speed graphs in Figure 5b, the speed profiles are nearly horizontal with respect to time. As the vehicles approach the potential conflict point, the distance between them starts to decrease until one of the vehicles crosses the conflict point.