The increasing number of electric vehicles (EVs) on the roads has raised concerns regarding fire safety in road tunnels. With the higher energy density of batteries in EVs compared to traditional combustion engines, EV fires in tunnels can pose greater risks to drivers and passengers, resulting in more severe damage. This study simulates a 5.2 MW fire in a 700-meter tunnel section and evaluates the impact of different fire detection times on smoke distribution. Using the Fire Dynamic Simulator, numerical simulations were conducted to provide insights into the effectiveness of early fire detection and its potential impact on mitigating the risks associated with EV fires in tunnels. The findings highlight the importance of emergency ventilation activation in reducing the hazards posed by fire spread upstream and enabling safe evacuation of individuals in potentially life-threatening situations. The study highlights the significant challenge in managing emergency ventilation in modern road tunnels and emphasizes the need for improved fire detection systems to ensure the safety of drivers and passengers in case of emergency.