The theory of improving the appearance of the urban environment in an effort to improve public safety and reduce crime, known as the "broken windows theory", has been vigorously debated since its appearance in a 1982 article by social scientists James Q. Wilson and George L. Kelling. According to Davies, the results of a recent policing experiment in Rotterdam may provide "some much needed proof for this theory."
The project, called ‘The Neighbourhood takes Charge', focused on addressing quality of life improvements identified by local residents, of which the top three concerns were street cleaning, dog mess, and reducing traffic speeds.
According to Davies, "police started focusing on making streets cleaner, removing graffiti, speed gunning motorists, increasing police visibility and improving the public realm. But rather than neglecting serious crimes, they actually saw some dramatic reductions in all sorts of crime over a two year period, including: drug crime dropped by 30%; burglary dropped by 22%; vandalism dropped by 31%; traffic offences dropped by 19%; theft dropped by 11%; violence dropped by 8%."
It's unclear from Davies' article how much of the reduction in crime can be attributed to the individual efforts he mentions, such as merely increasing police visibility.