Mobile speed cameras will be monitoring Edinburgh's roads for 12 hours a day over the summer.
Mobile speed vans are to have an increased presence in Edinburgh
They will target speeders between 0700 GMT and 1900 GMT.
Until now the cameras have only been out between 0800 GMT and 1600 GMT, but research shows a significant amount of collisions occur at evening rush hour.
The transit-sized vans, which are brightly coloured, can be seen parked at the side of roads in the Scottish capital.
Police officers warn that drivers will not get flashed as it is a video camera that records the speeds, rather than the type of camera used in the fixed safety cameras.
Colin McNeil, Lothian and Borders Police safety camera partnership manager, said drivers may not even be aware that they have been caught until the letter drops through their letterbox.
He said: "We really don't want to catch people speeding, we are here to make roads safer.
"We all know that if we travel at high speeds we are more likely to be involved in collisions and that injuries will be serious, possibly fatal.
"Our aim is to make speeding as socially unacceptable as drink driving or not wearing a seatbelt - things that you just don't do anymore."
Quality of life
Councillor Andrew Burns, Edinburgh Council transport leader, said road safety measures had reduced the number of people dying or being injured on the streets of Edinburgh.
"All of these measures have played their part in an impressive road safety record in recent years," he said.
"No children have been killed on Edinburgh's roads for the last three years. In the three years previously eight children lost their lives, which is a price we are just simply not willing to pay.
"Improving road safety can directly improve the quality of life for neighbourhoods and families.
"We want to continue the good work and increasing the hours that mobile speed camera vans operate is a positive step towards this."