BOSTON – The state’s top transit cop says serious crime on commuter trains, subways and rail stations fell by 20 percent during the first half of the year.Massachusetts Transit Police Chief Paul MacMillan reported Thursday that incidents of larcenies and attempted larcenies decreased by nearly 30 percent, from 311 to 220, while robberies and attempted robberies dropped by 20 percent, from 105 to 84, compared to the same period in 2008.The Massachusetts Bay Transportation Authority (MBTA) reported a total of 368 crimes such as larceny, robbery, burglary and assault from Jan. 1 to June 30. During the same six-month period in 2008, a total of 475 crimes were reported.Additionally, MacMillan said reports of indecent assaults dropped from 39 to 33, while drug offenses dipped sharply, from 83 to 36. “There have been no rapes, homicides, or attempted murders this year on MBTA property,” he said, noting that the MBTA is the state’s second-largest property owner.MacMillan said Transit Police have intensified fare-collection efforts, with stops for fare evasion up by 200 percent. Transit Police reported 1,399 fare evasion incidents, filed as fraud in the list of crime categories, during the first six months of 2009. The chief described the initiative as “a dramatic increase” over the 431 incidents during the same period last year.The police have also stepped up efforts against pickpockets and posted signs in train cars warning riders that indecently rubbing against another passenger is a crime.”The involvement of our employees and the riding public is crucial to making the T as safe as possible,” said MacMillan. “Our awareness campaigns have been a success from the standpoint of alerting our passengers to potential problems.”MacMillan credited MBTA General Manager Daniel Grabauskas for his support of the Transit Police. “Through his leadership we have the highest level of officers in the history of the department. He has been a strong advocate of our initiatives to lessen crime on the MBTA,” the chief said.