About 2,500 traffic police officers will be on London's streets during rush hours following the deaths of six cyclists over 14 days.
Operation Safeway will see Metropolitan Police officers deployed at 166 key junctions where they will issue fixed penalty notices to people breaking road traffic laws.
There have been 14 cyclist deaths in London this year, nine involving HGVs.
The officers will also be offering advice to anyone seen putting themselves or other road uses at risk. This includes pedestrians, cyclists, motorcyclists and other motorists.
The number of police and locations will rise as the operation progresses. The force said it would continue until Christmas when it would then be reviewed.
The five cyclists who died between 5 and 13 November are: Brian Holt, 62; Francis Golding, 69; Roger William De Klerk, 43; Venera Minakhmetova, 24, and a 21-year-old man from St John's Wood whose name has not yet been officially released by police.
The number of cyclists killed so far in crashes in London this year is the same as the figure for the whole of 2012.
Supt Rob Revill said: "Our aim is to reduce the appalling number of people who die or are injured on London's roads each year.
"Every road death is a needless tragedy that wreaks devastation for the victim's friends and family. Every serious injury is life-changing and distressing."
He added: "We welcome the recent debate around road safety but it is irrefutable that the Met and the public have a duty to ensure that we all take the very best care on the roads."
Last week, Mayor of London Boris Johnson said headphones were an "absolute scourge" and he would consider banning cyclists from wearing them.
However, BBC London transport correspondent Tom Edwards said at Bow roundabout the police were advising cyclists about wearing helmets and high visibility jackets, rather than advising them about wearing headphones.
There have been calls for HGVs to be banned in rush hours, with former Olympic cyclist Chris Boardman saying "the longer we delay, the more lives will be lost".
But Mr Johnson has said imposing a peak-time ban risked damaging London companies and creating a "serious influx as soon as the ban is over".
Mr Johnson also said safety on the roads must be improved and he was looking at investing the "thick end of £1bn" to make cycling in the capital safer.
Last Monday, the Met carried out spot-checks on cyclists and HGVs in Vauxhall, south London.
In four hours, the officers stopped 70 lorries and issued 15 fixed penalty notices for offences such as the vehicles not being fit for the road.
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