## 3 Data and Scenarios
### Work Zone Location and Scenarios  
The work zone sites are located northeast of Nanjing on the G36 highway. Generally, there is a construction vehicle with a lane-change warning sign, shown at the video's endpoint. And the taper areas usually start 150-200 m ahead of the construction vehicle, as shown in Figure 3. To investigate the vehicle merging characteristics under different traffic states and layouts, in this study, we selected eight work zone sites to form three scenarios, which are described in Table 1.  
Figure 3: Aerial views of representative work zone sites of all three scenarios. Site B3 and Site C1 belong to Scenario 1, Site B2 belongs to Scenario 2, and Site A4 belongs to Scenario 3. Figure 2: Measurements of kinematic vehicle indicators. In selecting the sites, our principle was to ensure diversity in traffic conditions and work zone markings as well as lane configurations. The traffic conditions needed to encompass low traffic flow, saturated traffic conditions, and traffic oscillations. Regarding work zone markings and lane configurations, the sites had to cover varying numbers of lanes and the presence or absence of solid white lines. Based on these criteria, we ultimately selected eight work zone sites and categorized them into three scenarios. The representative characteristics of each scenario are as follows:  
* Scenario 1: This scenario represents a basic three-lane configuration where the leftmost lane was closed for construction. Under typical conditions, traffic in this area remains light, allowing vehicles to pass through at higher speeds, as depicted in Figure 4a,b. However, on 18 May 2022, during the evening peak hours, the inner lane closure resulted in denser traffic, with 1700 vehicle trajectories captured in a 15-min video, as shown in Figure 4c,d. This scenario covers a wide range of traffic volumes and densities, offering a comprehensive dataset for analyzing vehicle merging behavior under varying conditions. * Scenario 2: The work zones in this scenario occur near the end of solid white lines, where drivers must cross the solid white line to change lanes. These markings are typically used in weaving sections, tunnels, and bridges to prevent lane changes. As shown in Figure 4e,f, merging behavior under these conditions often induces traffic oscillations, even in lower traffic volumes, as drivers hesitate due to the legal restrictions associated with crossing solid lines. In the following section, we further explore how merging behavior differs in work zones with and without solid white lines. * Scenario 3: This scenario involves a two-lane configuration where traffic oscillations are observed, as shown in Figure 4g,h. With only one open lane, vehicles must either accelerate or yield to merging traffic, but they lack the option to make discretionary lane changes to another lane, as is possible in Scenario 1. The layout of this work zone creates additional complexities in merging behavior, which will be discussed further in the next section. Ensuring diversity across these conditions allows the findings to be more broadly applicable to other highway work zones beyond the specific locations studied. It is worth noting that, in some cases, such as at Site B4 and Site A4, Lane 4, vehicles maintain relatively high speeds even when approaching the work zone. This phenomenon can be explained by two main factors. First, it relates to the length and distance of the lane closure as well as the smoothness of the cone placement, which can provide a clearer and more navigable path. Second, the traffic flow plays a significant role in influencing this behavior. The complexity of these interactions generally results in longer decision-making times for drivers and more short-term lane-changing opportunities, reducing the need for deceleration. Consequently, fewer speed reductions are observed under these conditions.