Bus passengers travelling through a west London station will face prison-style weapons checks.
If it proves a success, it could be introduced into other areas.
A metal scanner, based on technology used in prisons, has been installed at Hammersmith Bus Garage by police as part of a week-long trial.
The site was chosen for the number of public disorder offences and the influx of people from across London who use the station daily.
Hammersmith police said it hoped those carrying knives would think twice.
Police officers will be on hand to carry out searches on anyone who triggers the scanner.
Operation Blunt, part of the Met's anti-knife initiative, will run from Tuesday until Friday.
If it proves a success, it could be introduced into other London boroughs.
Chief superintendent Heather Valentine said: "Knife crime is a dangerous culture and one that we wish to remove from our community.
"I hope those carrying a knife in Hammersmith and Fulham will take note of this operation and think twice before doing so."