The systems are open to public insofar as you must be escorted by a staff member with proper identification. This is usually during a tour of the Capitol complex. However, during votes, the House subway is restricted for Members-only. Also, the Russell Subway is restricted to Members and staff-only (Senate staff tours use the Russell subway to reach the Capitol) during times when the Senate is voting. Additionally, since the terrorist attacks of September 11, 2001, restrictions have been placed on visitors using the Senate subway between the Hart and Dirksen buildings.
The system was built in 1909 to link the Russell Senate Office Building to the Capitol. The Dirksen Senate Office Building was added to the system in 1954 and the Rayburn House Office Building in 1965. The system first ran on March 7, 1909, and was last updated in 1994.
An accident occurred on October 2, 2007 in the Rayburn to Capitol subway line when a car failed to slow down when it reached the end of the line. The operator was injured and taken to the hospital for observation.