London's cycle superhighway work starts
Work has begun on the north-south route of a £160m cycleway across London.
Mayor Boris Johnson officially started the work on the so-called "superhighway" at St George's Circus in Southwark, south London.
The north-south route will operate for more than three miles, from King's Cross to Elephant and Castle.
The east-west route will see cyclists segregated from traffic over 18 miles, from Barking to Acton.
Ashok Sinha, chief executive of the London Cycling Campaign, said the project was "absolutely" a good thing.
He said: "The partition for cyclists will substantially reduce serious injuries and fatalities from lorries. Boris [London Mayor] is keeping good his promise."
But, opponents said the scheme will take too much road space and lead to an increase in congestion.
London First, London Travelwatch, City of London, Canary Wharf and the London Taxi Drivers' Association have all voiced concerns.
City of London said while it was not opposed to the principle of "cycle superhighways" it had concerns about the reduced accessibility from closing side road junctions.
It also had concerns about extra hazards for pedestrians and said: "Our primary concern, as ever, is for the safety of all road users."
The routes are expected to be open next year.
Mr Johnson, said: "This is a big day for cycling and for London, the culmination of years of campaigning by cyclists and months of planning by TfL.
"Getting more people on their bikes will reduce pressure on the road, bus and rail networks, cut pollution and improve life for everyone, whether or not they cycle themselves."
TfL hopes the number of cyclists will treble as a result of the new routes.
The first phase of work through St George's Circus is intended to transform Blackfriars Road "from a car-dominated street into a new urban boulevard".
The work will include planting new trees, almost 1,858 sq m (20,000 sq ft) of new space for pedestrians and a two-way segregated cycle track.
Work on the route south of the river will be finished by the end of the year. North of the river, work will begin in the summer and and was due to be complete spring 2016.