Mayor of London Boris Johnson visited St George's Circus on Tuesday to mark the official start of more than a year of roadworks to create a new north-south cycle superhighway.
Asked about the current disruption to local traffic, the Mayor replied that "it will be worth it in the end".
Work on the route south of the river will be finished by the end of the year, with the City of London section due for completion next spring.
"The early superhighways were largely paint on the roads," he said.
"Although that did actually achieve a significant shift of people from public transport and cars to bikes, it wasn't deemed good enough by cyclists and other groups.
"This is going to physically segregated. There will be a kerb between you and the rest of the traffic if you're on a bike, and that is a whole lot safer."
Cllr Mark Williams, Southwark's cabinet member for regeneration, planning and transport, said: "The Blackfriars Road project is a real milestone for Southwark and will bring significant benefits for our residents.
"The new high quality cycling route will help us meet our target to more than double cycling and open it up to more people. The Cycle Superhighway will link in with our own 'Southwark Spine' cycle route which will connect the Thames to Crystal Palace.
"The project also brings huge pedestrian benefits and Southwark Council is providing an additional £2.2 million of investment to help deliver a high quality boulevard on this historic road."