Tunnels are essential infrastructure across different transport systems to help shorten distances and travel time. There are tunnels across road systems, rail and metro systems, through mountains, below the sea. These are expensive infrastructure that need to last long, endure harsh environmental conditions and must remain free of major maintenance and repairs in its lifetime. Proper waterproofing and protection from chemicals is critical to ensure this. GS TPO Tunnel membrane allows contractors to extend the service life and enhance the safety of such structures in a most cost-effective manner. It protects the tunnels against damage from moisture, water pressure, puncture, chemical attacks, corrosion and other environmental conditions, while providing reliable, durable and flexible sealing and leak-tightness over long years.