When are protected only left turns typically implemented?

Protected only left turns are typically implemented at intersections with a high volume of through traffic, especially when there are more than two through lanes and constrained sight distance. In such scenarios, a protected left turn can enhance safety for left-turning vehicles by reducing potential conflicts with opposing traffic and situations where visibility is compromised.

High volumes of through traffic increase the likelihood of conflicts during a standard left-turn phase, where a vehicle may turn left while others are proceeding straight. By using a protected left turn, which allows left-turning vehicles to go while opposing traffic is held, safety is improved significantly. The presence of more than two through lanes often indicates a busy intersection, and constrained sight distance may make it difficult for drivers to judge gaps in oncoming traffic, further justifying the need for a protected turn signal that eliminates these conflicts entirely.

In contrast, low traffic or off-peak hours, while potentially relaxing the need for protection, do not typically necessitate protected left turns. Residential areas may also have different traffic patterns and considerations, which further separates them from high-volume intersection scenarios that require protective measures.