## 4 Data Extraction and Indicator Estimation  
To assess the overall behavior of the road users in our study, a comprehensive trajectory profile of the vehicles was required. After reviewing the literature, Kinovea (semi-automated tool) was found to be the most suitable tool for accurately tracking vehicles [33; 35; 36; 37]. One of the key advantages of using Kinovea is that it is an open-source and free tool with a user-friendly interface. Thus, Kinovea 8.27 was used in our study to extract the linear kinematic characteristics--such as the trajectories, speed and distance--from the video data of all the intersections. Table 2 summarizes the various indicators that were derived from these trajectories, along with their brief description. Several safety measures that can accurately calculate the safety of a traffic event have been proposed in earlier studies. For example, time to collision (TTC) and post encroachment time (PET) are some common safety measures [20]. These measures can be used to anticipate possible crashes and near misses, providing important information about the safety of traffic situations. Many of these measures can be derived from the trajectories of road users and a few other characteristics, like the weight and dimension of a vehicle [30]. Only those indicators that can be derived from the trajectories of vehicles were used in this study. Some clarification regarding the choice of indicators is presented in this section. Although TTC is the most commonly used surrogate safety indicator, its applicability is somewhat constrained; it requires the presence of a collision course to calculate its value and cannot be calculated for many of the less severe scenarios, which is a drawback. Given that, in this study, we are interested in situations spanning the complete severity continuum, \(T_{2}\) (time remaining for the latest road user to arrive at the potential conflict area) was chosen over TTC as it is a more adaptable measure [20; 30]. TTC counts the time before a potential collision, whereas \(T_{2}\) measures the time needed for the latest road user to reach the conflict area. When a crash is about to happen, \(T_{2}\) gives the same advantages as TTC, but also  
Figure 1: Brief Methodology of the study. supplies helpful information when there is no chance of a collision. As a result, this study used \(T_{2}\) rather than TTC as a reliable safety indicator. The other measure used in this study is distance. The main benefit of using distance as a measure is the simplicity of its calculation. There is an advantage to using straightforward universal measurements in comparison to complex ones that may be subject to misinterpretation [38]. This study focused on two forms of distances: the shortest straight-line distance between the road users' closest points and the distance along their predicted paths to the point of conflict (see Figure 2). The other surrogate measure is PET, which is defined as a time interval between the first road user's departure and the second road user's arrival at the point of conflict [19], whereas gap time is used to check the temporal closeness of the vehicles [39]. The deceleration-based measures and speed were also estimated for the vehicles involved in the interaction to illustrate the possible consequences if the crash occurs.