The now disused St Margaret’s Head Tunnel was a structure originally formed as part of the Dunfermline to North Queensferry railway line, providing a link to the ferry service until the opening of the Forth Bridge in 1890 and remaining in limited use for freight until 1954. The vaulted roof and brick lined tunnel is located 15 metres below the A900 trunk road and the B981, adjacent to the northern approach to the Forth Road Bridge. Cordek were asked to supply a structural fill solution, encapsulated within a protective membrane to fill the entire cavity of the tunnel.