StacksVerified U.S. regulatory reference

23 CFR §650.503

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
The National Tunnel Inspection Standards (NTIS) in this subpart apply to all structures defined as highway tunnels on all public roads, on and off Federal-aid highways, including tribally and federally owned tunnels.