Case Study: CODEL’s Air Quality Monitoring in the Hsuehshan Tunnel, Taiwan

18-03-2025

Overview

The Hsuehshan Tunnel, also known as the Snow Mountain Tunnel, was the longest road tunnel in Asia and the fifth longest in the world at the time of its construction. Spanning nearly 13 km, it plays a critical role in Taiwan’s transportation network, forming a key section of the national expressway linking the capital, Taipei, with Yilan County. Completed at a cost of nearly $2 billion, the tunnel has significantly reduced travel time from over two hours to just thirty minutes, fostering economic growth and tourism in the region.

Project Challenges

Constructing the Hsuehshan Tunnel was an immense engineering feat. The tunnel cuts through Taiwan’s central mountain range, presenting complex geological conditions that required innovative solutions to ensure structural integrity and operational safety. Maintaining optimal air quality within the tunnel was a key consideration to protect commuters and ensure compliance with environmental standards.

CODEL’s Contribution

In 2005, 90 CODEL TunnelCraft II Air Quality Monitors (AQMs) were installed in the Hsuehshan Tunnel, supplied by the Atlas team. These included 41 CO monitors, 8 NO monitors, and 41 VIS monitors. These monitors provided real-time data on air quality parameters such as carbon monoxide (CO), nitrogen dioxide (NO₂), and visibility, ensuring safe driving conditions for motorists.

System Upgrade and Maintenance

To enhance monitoring capabilities, the TunnelCraft II AQMs were replaced in 2018 with CODEL’s advanced TunnelTech 200 Series AQMs—33 CO/VIS (2-in-1) units and 8 CO/NO/VIS (3-in-1) units. This upgrade improved reliability and accuracy, reinforcing the tunnel’s commitment to safety and efficiency. During the contractual five-year warranty period, which concluded in October 2024, Atlas provided quarterly maintenance services and necessary repairs, ensuring the continued functionality and durability of the monitoring systems.

Results and Impact

The integration of CODEL’s air quality monitoring solutions has played a vital role in maintaining safe environmental conditions within the tunnel. By continuously monitoring emissions and visibility, the system helps prevent hazardous pollution build-up, contributing to a safer and more efficient transport corridor.

The Hsuehshan Tunnel is now a model for large-scale tunnel infrastructure projects, demonstrating the importance of reliable air quality monitoring in ensuring the safety and sustainability of major roadways.