National Tunnel Inventory

The National Tunnel Inventory dataset was compiled on September 02, 2025 and published on August 26, 2025 from the Federal Highway Administration (FHWA) and is part of the U.S. Department of Transportation (USDOT)/Bureau of Transportation Statistics (BTS) National Transportation Atlas Database (NTAD). The National Tunnel Inventory (NTI) is a collection of information (database) describing the more than 500 of the Nation's tunnels located on public roads, including Interstate Highways, U.S. highways, State and county roads, as well as publicly-accessible tunnels on Federal lands. The inventory data present a complete picture of the location, description, and classification data for each tunnel, as well as any load rating and inspection information. The Specifications for the National Tunnel Inventory (SNTI) contains a detailed description of each data element including coding instructions and attribute definitions. The Coding Manual is published for each year of data collection; the manual is available at: https://doi.org/10.21949/1519104. For additional questions regarding regulations for the National Tunnel Inventory or the Coding Guide please contact the National Bridge and Tunnel Inventory team at NBTIS_Support@dot.gov. For questions on the geospatial component of the dataset, contact the NTAD team at NTAD@dot.gov. A data dictionary, or other source of attribute information, is accessible at https://doi.org/10.21949/1529051