Displaced Left Turns
A Displaced left turn (DLT), also known as a Continuous flow intersection (CFI), is a type of intersection in which all left-turns from the mainline road and in some cases left-turns from the minor roadway are made in a two-stage process. Vehicles first cross from the center to the opposite side of the roadway at an upstream secondary signalized intersection, and then proceed to the primary signal via a special roadway parallel to the mainline. At the primary signal, vehicles complete the left turn at the same time as through traffic because they are no longer in conflict with one another, due to the upstream crossover intersections.
Intersections of this type are becoming common and have performed well in other states including Michigan, Ohio, Colorado, Utah, and North Carolina. DLT intersections are proven to reduce delay at high-volume locations by allowing left turning traffic and through traffic to proceed through the main intersection simultaneously. This eliminates the additional time necessary to accommodate left turns at a traditional intersection. The DLT provides reduced delay and improved operation at high volume intersections, for a greatly reduced cost and physical footprint when compared with a grade-separated interchange. Additionally, a full displaced left turn intersection has only 28 conflict points where crashes could occur, in comparison with 32 conflict points at a traditional intersection and removes the left turn severe right angle crash type from the primary intersection.
INDOT has several displaced left turn intersections in various phases of project development. INDOT’s policy is to use alternative intersections, including the displaced left turn, where appropriate to support its ongoing commitment to improve safety and operational efficiency through innovation and cost-effective investments.
This graphic shows how major street left turn movements work at a DLT intersection.
This graphic shows how all the major street vehicle movements work at a DLT intersection.
This graphic shows how all the minor street vehicle movements work at a DLT intersection.