Putney Bridge has been closed today for three months and traffic is expected to be heavily congested in the surrounding area.
No vehicles are able to use the bridge, including buses, but pedestrians can cross, as can cyclists although they will have to dismount.
Bus passengers will have to get off to walk across before catching another bus at the other end. Transport for London (TfL) have ensured passengers will not have to pay twice as a transfer card or voucher will be issued by staff.
The work is expected to last until October. TfL have advised motorists to avoid the area where possible.
It coincides with work to Hammersmith Flyover will be closed westbound during the next four weekends. The westbound lanes will be closed from 10.30pm Friday until 5am on Monday. Drivers are advised to use the A40 Western Avenue via Warwick Road instead.
The A4 Talgarth Road westbound off-slip lane is also closed until further notice.
TfL say both works are being carried out during the summer because traffic levels are lower.