A 2-1 road (often called a 2+1 road) is a three-lane highway layout. It features a continuous middle lane. This middle lane alternates as a passing lane for each direction every few miles. A wire rope barrier usually separates the directions. This design prevents head-on collisions while allowing safe passing. It is a cost-effective alternative to building a full four-lane highway.
Mechanic Glossary
2-1 Road
A road design containing two lanes in one direction and one lane in the opposite direction, separated by a median or barrier.
Frequently Asked Questions
A three-lane road where the middle lane alternates as a passing lane for each direction.
Yes. They are safer than standard two-lane roads. The middle passing lane reduces risky passing maneuvers.
Signs and road markings warn drivers before the passing lane ends. The lane then shifts to the opposite direction.