This study investigated the effect of green phase countdown timer (CDT) on the reduction of drivers dilemma at signalized intersection. The proposed system provides the remaining green time to the drivers in real-time to support the stop/pass decision making. Driving simulator experiment equipped with the CDT indication system showed that the proposed system significantly increased the probability of selecting stop. Also, logistic regression analysis (LRA) revealed that the system reduced the probability of facing the dilemma and encouraged the drivers to decelerate earlier and stop before entering the intersection. Especially, it contributed to decreasing the approaching speed for the drivers who travels at high speed.