The new Northern line tunnel is being dug from a worksite on King William Street, using the underground spaces left over from the closed King William Street tube station. Former running tunnels have previously been used as circulation space at Angel and London Bridge stations. Before the project can be completed, the Northern line Bank branch will have to close for several months to allow the existing line to be connected to the new running tunnels. , this closure is planned to occur in late 2021/early 2022.