Just had this email from TFL
From Monday 16 March until the end of October 2020, London Bridge will be closed to all traffic except buses, licensed taxis, motorcycles and cyclists.
This is so that the City of London Corporation can carry out essential maintenance work on the bridge.
Expect queues when crossing the river using Blackfriars Bridge or Tower Bridge. Delays are also expected on roads in the surrounding area.
Travel outside of peak times and use alternative river crossings, including Vauxhall, Westminster and Lambeth bridges for a quicker and easier journey.
For more information, visit https://tfl.gov.uk/status-updates/major-works-and-events/london-bridge-works