Abstract: In order to increase the vehicle operating efficiency at the approaches of signalized intersections with variable lanes and make the upstream fleet transit smoothly into approaches, traffic characteristics of upstream variable lanes at signalized intersections are analyzed to ascertain the main lane-changing regions and lane-changing characteristics of the upstream fleet at approaches, which provides a basis for the detector layout of upstream variable lanes. Meanwhile, according to the variable lane control strategies based upon detector data, the detector trigger conditions and trigger timing are put forward. The suggested strategies are verified with simulation software VISSIM and specific examples. The results show that the method can increase the traffic capacity of signalized intersections, and the proposed trigger conditions and trigger timing can make the upstream vehicles transit smoothly into approaches.