Mobile speed cameras are to be used at accident hotspots to try to reduce the numbers of people being killed or injured.
Mobile speed cameras will help tackle road deaths
The first of five vans to be deployed across the city will be in place outside a school in Greenwich, south-east London, on Wednesday after parents asked for help in getting drivers to slow down.
Transport for London (TfL) says the mobile units will be clearly marked and police officers will wear highly visible clothing.
The initiative is part of TfL's strategy to reduce the 6,000 people killed or seriously injured on London's roads each year.
The parents of children at Deansfield Primary School on Rochester Way wrote to TfL after there were six accidents and two fatalities in two years on the busy commuter route.
TfL found that on average drivers were doing 43mph in a 30mph limit.
We are confident mobile enforcement will bring positive change to the speeding culture and reduce casualties
Jenny Jones, deputy mayor
The new mobile units are fitted with cameras able to detect speeding motorists more than half-a-mile away.
London's deputy mayor, Jenny Jones, said: "Too many children are killed or seriously hurt by speeding traffic.
"These mobile enforcement vans will play an important role in slowing drivers down, especially around schools and in community areas."
She said London had the highest toll of death and serious injury in the country - 18% of the total.
"We are confident mobile enforcement will bring positive change to the speeding culture and reduce casualties," she added.
The vans will add to the existing 650 speed and red light cameras around London.
All five will be painted bright yellow and blue and details of their locations will be published on the TfL website and be made available to local radio travel bulletins.