A train operator reported seeing a white male with a dog crossing from the C1 to the C2 track, at about milepost 22.5. Trains conducted track inspections and the train operator of a Pittsburg bound train located the man walking north on the C1 track. The man boarded the train and officers intercepted the train at North Concord Station. The train operator placed the man under citizen's arrest and he was cited and released. Northbound trains were delayed about 15 minutes as a result of this incident.