An experiment in London’s Underground has found crime declines in areas where police patrolling was recently seen, meaning potential offenders become apprehensive about police presence and adjust their crime behavior pattern accordingly.
Data from the experiment showed that four 15-minute patrols a day in some of the capital's most crime-ridden train stations reduced reported crime and disorder by 21 percent.
London’s Underground, akin to NYC’s subway system, was the first underground railway in the world, and now services more than 1.3 billion passengers per year. Of reported crime, train platforms—which previously did not have a regular police presence—experienced about 11 percent of the total, with the majority occurring on trains and in the concourse area.
For this experiment, conducted by University of Cambridge researchers in cooperation with the British Transport Police (BTP), the confined platform with finite entry and exit points was ideal for gauging patrol effectiveness.
"We wanted to measure what happens when police patrols are introduced into an urban environment for the first time in over 150 years,” said Barak Ariel, the first author of the paper published in Criminology.
The Cambridge team identified 115 London stations where reported crime was the highest. They randomly assigned 57 of the stations for police presence, using the remaining 58 as controls.
Twenty uniformed BTP officers were selected and trained to work exclusively on patrolling platforms for 15 minutes four times per day. Police were deployed four times a week, Wednesday through Saturday, at hours of peak crime. The officers were asked to conduct patrols in a random order, and encouraged to engage with the public while patrolling. In the six months the experiment was running, calls to police from platforms without a patrol totaled 3,549, while calls from platforms with an established police presence only totaled 2,817.
Examining crime data from the six months prior to the start of the experiment, the researchers found that recorded crime fell 14% overall in those stations treated with the new patrols. Interestingly, they also discovered that the vast majority of reduction in both crime and calls for assistance occurred when police patrols were absent—not when they were on the platform.
"The total crime prevention benefit of police patrols may be greater when they are absent than when they are present. In the London Underground experiment, we see a huge residual effect of brief appearances by patrolling officers after they leave," said study co-author Lawrence Sherman. “[The] paradox could have implications for debates on police priorities in an age of austerity, such as the benefits of investigating past crimes compared with the benefits of preventing future crimes.”