It would cost $200,000 a year to have a full-time police presence by the bike cage in Boston’s Alewife subway station. (I hope that’s the estimate for staffing the station more or less around the clock, or I need to consider a career change.) So the city is cutting corners by providing only two dimensions of cop instead of three. A cardboard cutout of MBTA officer David Silen has helped cut bike thefts by 67 percent.

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Stealing a bike is kind of a split-second decision, so if you glimpse a cop — or something that looks like a cop — you don’t really bother to walk fully around him and ascertain that he has depth as well as length and width. You just move on.

Flat Stanley Silen hasn’t cut bike theft so drastically on his own; the MBTA also sprang for video cameras and a new lock on the bike cage. Perhaps they can defray this expense by selling collapsible cop cutouts you can put up wherever.

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