National Tunnel Inspection Standards (NTIS)

The National Tunnel Inspection Standards (NTIS) are set guidelines used by transportation authorities in the United States to regularly assess the safety and condition of tunnels. These standards specify inspection procedures, inspection intervals, and reporting requirements to identify issues such as structural damage, water leaks, or deterioration. The goal is to ensure tunnels remain safe for the public by systematically monitoring their condition, prioritizing repairs, and maintaining infrastructure integrity. NTIS helps standardize inspections across regions, promoting consistent safety practices and preventing accidents or failures.