Operational Advantages of Contraflow Left-Turn Pockets at Signalized Intersections

The contraflow left lane has been implemented in Handan, China. For safety reasons, left-turning vehicles cannot have access tothe CLT pocket all along the lane, but only through an entrance. The inflow can be controlled by a pre-signal near the entrance. A proposed signal phasing plan with protected left-turn phases on all approaches is illustrated. The contraflow treatment will benefit an intersection as long as left-turn demand is high. Increased left-turn movement capacity can mitigate or eliminate spillover. In some cases, additional left-turn capacity could allow left-turn green times to be reduced, such that green time could be reallocated toward other turn movements at the sign. This CLT treatment is not recommended for all intersections, but only for high left-turn volume demand and appropriate existing geometric designs.