Patrol Officers are the Boston Police Department's first line of response when the city reaches out for help. All 911 calls -- from a complaint about a barking dog to a report of gunfire -- are answered primarily by patrol units, who ride through Boston's neighborhoods at all hours of the day and night in uniform and marked police cars. With more than half a million calls a year, patrol officers are not just highly trained but highly experienced in the challenges of urban policing. And they're a huge part of the reason Boston has one of the lowest crime rates of any large city in the country. There's almost nothing they haven't seen and absolutely nothing they won't handle.