Transportation systems are complex dynamic systems that hard to be modeled exactly. The correct model need model verification and validation. This paper presents an improved discrete event simulation model of traffic light control on a single intersection. Model is developed using SIMULINK / SimEvent toolbox provided by MATLAB. We proposed the improved model using controller with two input switches and two output switches combined with traffic signal logic block. In this research, the fixed time controller algorithm is located within traffic signal logic block. The intersection model uses four approaches, and each approach consists of one trough stream and one right turn stream. Each stream is modeled as an M/M/1 queue. FIFO discipline is applied to the vehicles queue in each stream. Inter arrival time between vehicles is modeled using exponential distribution. Model validation is done in two different scenarios of inter-arrival time between vehicles 15 s (for low traffic volume), and 5 s (for high traffic volume) respectively. Experiment results show that the number of vehicles in queue and average waiting time of low traffic volume is lower than high traffic volume. That means the model has functioned correctly.