Proliman and Kejaksaan Junction in Sukoharjo regency are signalized intersections equipped with a countdown timer. The installation of this tool aims to improve the level of service at the two intersections. This study intends to evaluate the performance of the countdown timer by comparing level of service and level of traffic violations when the countdown timer is turned on and off. Data related to intersection service levels was calculated using the formula in the Indonesian Road Capacity Manual (MKJI), while traffic violations were analyzed using Independent T Test. Based on the results of the analysis, it was known that there were differences in the level of service and traffic violations between two conditions. At both intersections, the delay was higher when the countdown timer was activated, with a difference of 2,9 seconds / vehicle for Proliman Junction and 1,4 seconds/vehicle for Kejaksaan Junction. The level of service at Proliman Junction increased to C when the countdown timer was turned on, while at the level of service at Kejaksaan Junction remains C for both conditions. The C level of service indicating that delay at the intersection is between 15 and 25 seconds. At both intersections, the rate of traffic violations was higher when the countdown timer was activated, with an increase of 34% for Proliman Junction and 19% for Kejaksaan Junction. Based on the results of different tests, it was known that there was a significant difference in the number of traffic violations when the countdown timer was turned on and off, with a p-value of 0,001 for both locations (H0 was rejected).