A plan by the Brunswick Police Department and the Federal Railroad Administration could make the department the first in the country to use drones to patrol for trespassers along railroad tracks in town. The project, which is still in its infancy, also would make the Brunswick Police Department the first in Maine to use drones to look for potential criminal activity, rather than at a crime scene or at a crash site. But both state and federal officials say they will not be writing tickets if they spot people using the camera-equipped quadcopters. “This device will only be used for detection, not enforcement,” said Desiree French, a spokeswoman for the railroad administration. Brunswick is the current northern terminus of Amtrak’s Downeaster line, and if plans are approved to extend seasonal Downeaster service to Rockland, police would have to patrol an extra four miles of track, Brunswick Patrol Commander Thomas Garrepy said. “We can cover a mile in every direction in a fraction of the time (with a drone),” Garrepy said.