Indonesia has more than 270 million people, most of whom use private transportation to access various places. The high population also influences the number of vehicle uses in Indonesia. Congestion is often caused by vehicle users violating traffic lights at road intersections. Traffic violations are no longer commonplace for motorists in Indonesia and have become a driving habit. The regulations regarding driving contained in Law Number 22 of 2009 concerning Road Traffic and Transportation (UU LLAJ) are often ignored as if they do not cause problems. Quantitative methods were used to answer research conducted at Simp crossing lights. Medan City Script. Data from research analysis showed that there were 96 traffic light violations during 3 red light changing times. This research was conducted to look at the violations committed as well as the factors that influence the occurrence of traffic light violations in Medan City.