The Forth Road Bridge was opened in 1964 and tolls were charged until their abolition by the Scottish Government on February 11, 2008.
The bridge is maintained by the Forth Estuary Transport Authority.
A replacement crossing is planned and in December 2007 Ministers chose the option of a cable-stayed bridge upstream of the existing bridge.
The new bridge will be the single largest transport project for a generation and cost between £3.25 billion and £4.22 billion.