A ban on northbound motor traffic turning left into Abbey Street from Tower Bridge Road came into force on Friday, just over one year after the death of cyclist Ellie Carey.
The banned left turn is the latest in a series of measures – including advanced stop lines and trixi mirrors – which have been introduced at the junction since the death of cyclist Ellie Carey in December 2011.
Ms Carey, a 22-year-old student from Guernsey, was killed at the junction on 2 December 2011 when her bicycle was hit by a lorry.
Transport for London says it will announce plans for further changes to the junction – including improved pedestrian crossings – early in 2013.
"Residents' delight that these safety improvements are finally being made is tempered by the scandalous lack of urgency shown by TfL," said Grange ward councillor Mark Gettleson.
Last month – to coincide with the World Day of Remembrance for road traffic victims – more than 200 cyclists took part in a sponsored ride around the north coast of Guernsey to raise funds for the Eleanor Foundation which has been set up by Ms Carey's family.
The event raised more than £4,000 for the foundation, as well as charities RoadPeace and Water Aid.