Speed cameras are getting smaller, smarter and more mobile as local governments increasingly turn to them to nab speeding drivers.

Prince George’s County has quadrupled its fleet of speed cameras over the last year with the purchase of nearly five dozen mobile cameras, which are battery-operated and can be easily relocated, unlike the more commonly used fixed-pole cameras, which require underground wiring. The county gave out more than 349,000 citations in the first nine months of the program, which began in September.