State Police Tunnels Barracks

State Police Tunnels, which opened in December 1995, is situated above the South Boston portal of the Ted Williams Tunnel (TWT). Originally designated as the Third Harbor Tunnel, the TWT was the first section of the Central Artery/Tunnel Project (the "Big Dig") to be completed, inaugurated on December 15, 1995. The Tunnels barracks oversees 45 miles of highways, including all Big Dig roadways and the intricate system of highways, tunnels, ramps, and connectors.

The Big Dig is the largest public works project in the nation's history and was constructed while maintaining service to the old elevated highways. Major roadways covered include I-93 North from Exit 18 in South Bay to Exit 28 in Charlestown, I-93 South from Exit 26 in Somerville to the South Bay Mall in Dorchester, I-90 (MassPike) East and West between Interchange 19/20 in Allston-Brighton and Route 1A in East Boston, and the Leverett Connector North and South, between Somerville and Leverett Circle.

Other tunnels patrolled by H-9 personnel include the Sumner and Callahan Tunnels under Boston Harbor, the CANA Tunnels under City Square in Charlestown, and the Prudential and O'Neil Tunnels running east and west.