PORTLAND (AP) — 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 (http://bit.ly/1aYzaAx ) rumble strips are a “low cost … high return” effort, especially at a time drivers face more distractions from mobile devices.

The cost is about $135,000 for every 20 miles of road.

She said rumble strips are likely to become more widespread in coming years.