Safety Assessment of Auxiliary Lanes in Freeway Interchange Weaving Areas based on Traffic Conflict Technique

Yao, Rao; Xiang, Qiaojun; Gu, Xin; Guo, Yifan; Zhang, Ting · 2017 · OpenAlex-citations

DOI: 10.1051/matecconf/201712404005

archive: archived pipeline: cataloged verified

Get this paper ↗ (DOI — opens at the source; we link to it, we don't host it)

Summary

This study addresses the safety impacts of auxiliary lanes (ALs) in freeway interchange weaving areas, a critical component of highway networks where traffic flow is complex and safety risks are elevated. While existing design guidelines primarily focus on capacity analysis, there is a lack of detailed safety assessments for ALs, particularly those tailored to specific traffic compositions like those in China. Traditional safety analyses relying on historical crash records suffer from data scarcity and reliability issues. To overcome these limitations, the authors employ the Traffic Conflict Technique (TCT), which uses surrogate safety measures to evaluate safety performance under various design and traffic conditions. The research utilizes a simulation-based approach combining the microscopic traffic simulation software VISSIM and the Surrogate Safety Assessment Model (SSAM). The study focuses on a semi-cloverleaf interchange with a typical weaving area, using field data collected via unmanned aerial vehicle (UAV) photography for model calibration. The simulation model accounts for vehicle parameters (cars and heavy goods vehicles), driver behaviors (car-following, lane-changing, and transverse behavior), and geometric conditions. The model was validated against observed data, showing mean absolute percentage errors of 1.648% for travel time and 9.69% for conflict counts. The experimental design involved 72 simulation scenarios varying ramp spacing (200–400 m), mainline lane numbers (1–3), through volume (1000–1400 veh/h/ln), weaving ratio (0.2–0.4), and heavy vehicle percentage (25%–50%). Safety performance was assessed using the Traffic Conflict Modification Factor (TCMF), calculated by comparing traffic conflict rates before and after the implementation of ALs, with Time to Collision (TTC) < 4s serving as the conflict threshold. The results indicate that installing auxiliary lanes significantly reduces traffic conflict rates across all tested scenarios, with TCMF values consistently below 1.0. The effectiveness of ALs is influenced by several factors. Specifically, the safety benefits are more pronounced when ramp spacing is shorter, as ALs provide necessary space and time for weaving maneuvers that are otherwise constrained. The reduction in conflicts is also significant under high weaving volumes. Furthermore, the number of mainline lanes affects the magnitude of safety improvement, with varying TCMF values observed across different lane configurations. The study confirms that ALs mitigate the disturbances caused by frequent lane changes and speed differentials in weaving areas. The significance of this research lies in providing a quantitative method for assessing the safety benefits of auxiliary lanes, offering support for decision-making in the planning and design of freeway interchanges. By demonstrating that ALs can effectively reduce traffic conflicts, particularly in areas with short ramp spacing and high weaving volumes, the findings advocate for the strategic implementation of ALs to enhance safety. The use of TCT combined with simulation offers a practical alternative to crash-based analysis, allowing for the evaluation of safety impacts for facilities that are yet to be constructed or modified.

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed.

Summary generated by qwen3.6-27b-prismaquant on 2026-06-26; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• intersection design