Simulation-Based Performance Analysis of Ventilation and Fire Protection Strategies in Road Tunnel Fires: Review

Tunnel fires are among the most critical hazards in transportation infrastructure due to rapid smoke spread, high heat release, and constrained evacuation opportunities. In recent years, computational simulation has become the primary tool to evaluate tunnel fire safety, enabling detailed analysis of smoke propagation, ventilation effectiveness, suppression systems, and evacuation performance. This review critically synthesizes studies published between 2015 and 2024, with focus on simulation approaches using CFD-based fire modeling and agent-based evacuation tools. Comparative discussion shows that while longitudinal ventilation is effective for moderate fire sizes, its performance in large-scale fires is inconsistent, particularly when coupled with suppression. Water-mist and sprinkler systems demonstrate significant potential in reducing HRR and gas temperatures, though their interaction with strong airflow remains inadequately resolved. Evacuation models highlight the dominant role of visibility and toxic gases in determining egress time, yet often rely on simplified behavior assumptions. The distinct contribution of this paper is its integrated assessment of ventilation, suppression, and evacuation simulations, clarifying contradictions across studies and identifying gaps such as coupled multi-system modeling and validation under extreme fire conditions. The review concludes with recommendations for more realistic, hybrid simulation frameworks to support tunnel fire safety design.