A Displaced Left Turn (DLT) intersection utilizes a signal-controlled left turn lane that crosses opposing traffic on the same split road prior to a direct turn onto an intersecting road. An alternative name for DLT is Parallel Flow Intersection (PFI).
Conventions for the LEFT turn from the split road onto the cross street are:
- Naming Convention: to [cross street name] [direction] (i.e. "to SR-741 N")
- Road Type: Ramp
- Junction Angles: Between 1 and 43 degrees for the first turn instruction (“stay to the left”), while the second instruction may vary based on local usage (usually between 45 and 90 degrees for “turn left”).
- Junction Position: The initial junction ideally should be as close to the start of the solid white line as possible (if present) for the dedicated turn lane.
- Elevation: -1 (or anything that differs from the road that the ramp segment crosses). No junction should be created with the opposing roadway, and the different elevations help prevent automated map problems suggesting that a junction be created.
Conventions for the RIGHT turn from the cross street onto the split road are:
- Naming Convention: Unnamed
- Road Type: Ramp
All other turns at the intersection are treated as standard at-grade connectors. Due to the potential number of at-grade connections in addition to the ramp segments, care must be taken to ensure that all turn restrictions are properly set.
Sample DLT as it appears in Waze Map Editor (permalink):
