## 4 Discussion  
This research aims to examine the driving behavior characteristics and the determining factors influencing them within tunnel-interchange connection sections. Drawing upon 11 highway project instances, the study creates 72 road models and 216 corresponding  
Figure 18: Analysis of failure samples. driving simulation scenarios. Comprehensive driving data were collected and processed, yielding indicators related to CF and LC maneuvers such as driving speed, headway, the duration and angle of LC, and the accepted gaps. These indicators shed light on the behavioral patterns exhibited by drivers under varying road conditions. The experimental findings highlight noteworthy primary and interaction effects of CD, IV, and TC on driving performance. Particularly, under fluctuating traffic volumes, CD significantly shapes drivers' decision-making concerning LC gaps. To further clearly quantify these effects, Table 11, informed by [PERSON]'s test results, summarizes the thresholds of CD and IV's impacts on various behavior indicators. The spacing between the tunnel and interchange, referred to as CD, is a pivotal factor affecting driving behavior. When the CD falls below 700 m, certain behavioral indicators notably differ from those observed in GDS. For instance, drivers demonstrate more urgency in LC behaviors within small spacing scenarios, reflected in LCD of 2 to 5.5 s and accepted gaps ranging from 2.5 to 4 s, which elevates the potential for rear-end risks, indicated by a sharp increase in DCC max and failure rate. Similarly, an extended headway can compromise traffic efficiency, especially under high-volume conditions, potentially leading to congestion. Past studies suggest that compared to a tunnel-interchange spacing of 500 m, road capacity decreases by approximately 7.6% to 9.67% when the distance shrinks to 300 m [13]. Thus, for maintaining driving stability and traffic efficiency, it is recommended that the information volume in the diverging area should not exceed nine units. If the CD between the tunnel-interchange falls below 500 m, the information volume should ideally be capped at seven units. In regions with substantial directional information, clear and concise prompts should be utilized to guide drivers effectively toward the correct choices. In contrast to other indicators, drivers' gap acceptance selection is primarily influenced by TC and exhibits significant interaction with CD. This could be attributed to the inverse relationship between the average headway and traffic volume. Under conditions of low-density traffic (1 st LOS), the average TH is relatively large (>4 s), allowing drivers to identify suitable gaps without speed adjustments. However, with escalating volume, the average TH within the 3 rd LOS falls to below 3 s. In such circumstances, combined with a short CD (below 500 m), drivers are faced with the challenge of rapidly identifying suitable gaps within a limited LC window and promptly transitioning to the outer lane. The critical accepted gap drops significantly from 4 s to 2.73 s, which is considerably lower than that in general sections. The distribution of gap acceptance offers additional insights into the distribution of other LC indicators under conditions of reduced spacing. It is worth noting that the traffic conditions examined in this study, based on field surveys, consider a relatively conservative 1 st to 3 rd LOS. If traffic density continues to increase, gap acceptance behavior could pose an even greater challenge for drivers. However, this hypothesis requires further investigation for validation. To enhance road safety, considering the role of navigation systems and Cooperative Intelligent Transportation Systems (C-ITS) is crucial. Building an effective in-tunnel navigation system could preemptively inform diverging vehicles of the distance to upcoming exits. Moreover, emerging technologies like C-ITS, which facilitate vehicle-to-everything (V2X) communication, are particularly relevant in tunnel-interchange scenarios.