Blackwall Tunnel is going to close for three nights so "critical repairs" can be carried out to the tunnel's fire detection system.

Nearby roads and routes across the river are expected to be extremely busy during the closure of the The River Thames crossing which links Greenwich to Tower Hamlets through a pair of road tunnels, and delays are likely according to TfL.

The closure will be in place from 1am on July 21 to 5am on July 23, and 1am on July 25 to 5am on July 26.

TfL said it needed to undertake 'planned' safety critical works within the Blackwall Tunnel which will require the closure of the southbound tunnel - the northbound tunnel will remain open throughout.

Whilst the southbound tunnel is closed, roads in the surrounding area and nearby alternative routes across the river are expected to be busy and delays are likely.

People travelling locally on Sunday 25 July are encouraged to use the Jubilee line or DLR services across the river.

News Shopper:

For longer journeys, people are advised to consider routes away from the centre of London, such as the A406 or M25 and use river crossings further out to complete journeys.

Glynn Barton, TfL's Director of Network Management, said: 'Safety is our top priority, and this critical closure of the southbound Blackwall Tunnel is essential to ensure the tunnel remains safe for people to use. 

'I'd like to ask people in the area who need to travel to plan ahead for their journeys and to thank them for their patience while we carry out this work.'

These works are to install a linear heat detection system (LHD) above the carriageway, which is part of an upgrade to the current fire detection system.

TfL says it regularly maintains its tunnels to ensure that they are safe to use, and upgrades to the Blackwall Tunnel's fire detection system are needed to ensure they work optimally in the event of a fire.

The Tunnel itself forms part of the A102, with the southbound tunnel passing underneath the O2 — formerly known as the Millennium Dome — as it travels below the river slightly downstream from its northbound neighbour.

Despite various stalled plans to build another Thames crossing, the Blackwall Tunnel remains the most easterly free road crossing on the river, with only the Dartford Crossing (toll) and the Woolwich Ferry further east.