The expansion of an existing two-lane road by building a parallel roadway next to it, effectively creating a divided highway or dual carriageway. This method increases capacity and safety by physically separating opposing flows of traffic with a median, often utilizing the original roadbed for traffic in one direction.
Heard on the job
The province announced the twinning of Highway 11 will begin next spring, which should finally stop the head-on collisions on that stretch.
Related terms
Dualize
To upgrade a single-carriageway road by adding a central reservation and a second roadway.
Head-on collision
A crash in which the front ends of two vehicles traveling in opposite directions strike each other.
2+1 road
A three-lane highway where the middle lane alternates as a passing lane for each direction.