Historically, active fire protection in tunnels has been limited by significant logistical hurdles. The persistent wind from natural or forced ventilation creates a chaotic environment; smoke and heat are often swept away from the ignition point, making traditional heat detection unreliable. Furthermore, standard low-pressure sprinkler systems are largely unfeasible for tunnels, as the volume of water required for a major fire would demand impractically large piping and pump infrastructure.

Recent breakthroughs, however, have shifted this perspective. Full-scale testing demonstrates that high-pressure water mist can overcome these challenges. Thanks to its high momentum, the mist penetrates turbulent airflow to reach the fire directly—effectively slashing temperatures, halting fire spread, and protecting the tunnel’s structural integrity.