The Milligan Street footbridge entrance on Roe Street will move west from Monday, December 2.
Pedestrians and cyclists will continue to travel over the roof of the new Fremantle Line tunnel but use a new entry/exit point on to Roe Street, 150 metres west of Lake Street (see map).
The route change is because of building work on the temporary bus station on Roe Street for the next phase of the City Link rail project, sinking the Wellington Street Bus Station.
Cyclists, pedestrians, and motorists also will continue to experience temporary diversions on Roe Street, and the Principal Shared Pathway (PSP) between Lake Street and Nicks Lane.
The City Link rail project is due to be finished in the middle of next year.
It is one of the first stages of the Perth City Link, a Federal, State and Local Government supported project to connect the central business district and Northbridge.