# Study on modular smoke extraction with solid screen in urban road tunnel fires

## TL;DR

This study explores how to improve smoke extraction in urban road tunnels during fires using modular systems and solid screens.

## Contribution

The paper introduces optimal modular smoke extraction strategies and design thresholds for urban road tunnel fires.

## Key findings

- A smoke screen height of 1.5 m significantly improves extraction efficiency and reduces high-temperature zones.
- Dividing tunnels into five modular zones balances hazard control and system cost effectively.
- Unbalanced airflow distribution with 35% exhaust at proximate vents prevents plug-holing and maximizes CO extraction.

## Abstract

A series of numerical simulations were conducted to evaluate and optimize a modular smoke extraction system integrated with smoke screens for urban road tunnel fires. The study aimed to identify key design parameters and propose optimal strategies for tunnel-wide smoke management. The results show that smoke screen height is a critical factor, with a threshold of 1.5 m (25% of tunnel height) significantly enhancing extraction efficiency and reducing high-temperature zones, while vent-screen distance has minimal impact. Dividing the tunnel into five modular zones achieves the optimal balance between hazard control and system cost. Furthermore, an unbalanced airflow distribution strategy—allocating 35% of the total exhaust volume (180 m³/s) to proximate vents and 15% to distal vents—proves most effective in preventing plug-holing phenomenon and maximizing CO extraction efficiency. These findings provide specific design thresholds and actionable strategies for the optimization of transverse smoke extraction systems in urban road tunnels.