In order to improve the driving efficiency of intersections with waiting areas, the effect of setting waiting area was firstly equal to the increase of lane green ratio. Then a signal timing optimization model for intersection was developed based on National Electronic Manufacturers Association (NEMA) standard dual-ring phase with the objective of minimizing the average vehicular delay. Next, a genetic algorithm for solving the model was designed by considering the ring-barrier constraint in phase structure. Finally, the model and algorithm were applied to the example intersection. The results show that compared to the signal timing scheme obtained by Synchro software, the model can obtain the scheme with shorter cycle and lower average vehicular delay. The delay reduction of the proposed model ranges from 12.9% to 17.4% when only left-turn waiting areas are provided at the intersections, and from 17.5% to 25.5% when both left-turn and through-movement waiting areas are provided. Besides, the model is not sensitive to the value of queue clearance rate, and can obtain almost the same signal timing scheme at the minimum and maximum vehicular speeds.