The nightmare is approaching fast. On October 1, the roads of east London and the City will be put to the ultimate test with the three-month closure of Tower Bridge .

The Blackwall and Rotherhithe tunnels are likely to be put under even more pressure, as will the Woolwich ferry and bridges further west and every rat ran and advantage will be sought out by drivers unable to use the vital crossing for three months, including the busy Christmas period.

Transport for London is attempting to limit the fall-out as far as practical possible. Some 21,000 vehicles that use the crossing daily will have to find alternative routes as will cyclists.

TfL has banned all non-emergency roadworks on surrounding roads to help reduce the impact as well as put in place plans to remove any vehicles blocking key routes.

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They have also lifted the Congestion Charge for drivers using the official signed diversions – northbound over London Bridge and southbound over Southwark Bridge.

Three London Bus routes that use Tower Bridge (42, 78 and RV1) will be affected. Signed alternative routes for cyclists will also be in place and pedestrians will still be able to cross the bridge, although there will be three weekends when the bridge is closed entirely.

Planned diversions around Tower Bridge, taken from the TfL's closure website

Managing director of surface transport at TfL Leon Daniels said: “We’ve been working closely with the City of London to minimise the impact of this vital refurbishment and to ensure that Londoners have the travel advice they need.

“We do understand concerns about this taking place at the same time as Network Rail’s work on Tooley Street. However, our analysis has shown that combining the works will make only a small difference in disruption, whereas to do both separately would see road users face disruption continuously until late 2018.

The 122-year-old Tower Bridge was last refurbished in the 1970s and the structure now requires major maintenance, including re-decking of the lifting bascules, new expansion joints, waterproofing of the viaduct arches and resurfacing.

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Chris Hayward, chairman of the Planning and Transport committee at the City of London Corporation , said: “This decision to close Tower Bridge to vehicles has not been taken lightly. This course of action has been taken after years of extensive consultation and planning in conjunction with numerous stakeholders.

"We will use this time to repair, refurbish, and upgrade London’s most iconic bridge, which has gone without significant engineering works for more than 35 years.

“We recognise that these works may cause some frustration to residents and commuters, but these vital works really do need to take place.”

Go to tfl.gov.uk/tower-bridge-closure .