Namely establishes the left-turn waiting area in the big intersection, let the left-turn vehicles follow the direct vehicles to enter in the left-turn waiting area during the red period, pass through the intersection quickly as soon as the traffic light turns green.

Left-turn vehicles waiting areas established at large crossroads could reduce left-turn signal time and realize reciprocal transformation of time and space.

Appropriate method in determining the left-turn yellow interval in right-hand-side driving environment would result in signal timings that are either safer for left-turn vehicles or more efficient for intersections.

The left-turn flow is the bottleneck that leads to the traffic conflicts(congestions) at the signalized intersection;therefore,analyzing left-turn flow delay is the foundation of studying intersection delay.