The Maine Department of Transportation plans to install more centerline rumble strips on undivided highways in an effort to reduce head-on collisions and save lives. Department safety manager Duane Brunell said rumble strips are planned along Route 4 in Berwick and South Berwick and Route 111 between Biddeford and Alfred this fall. The state first installed centerline rumble strips along Route 4 in Turner and Route 1 in Woolwich in 2006. Since then, collisions and fatalities have decreased. Brunell told the Portland Press Herald that rumble strips are a ‘‘low cost . . . high return’’ effort, especially at a time drivers face more distractions from mobile devices.