This research describes a study of vehicle behavior and delay at signalized intersections. The objective was to develop a regression model based on simulation model developed from observed traffic behavior. The developed simulation model has reasonably wide range of applications. To illustrate that within the scope of this research a regression model for the prediction of optimum cycle times, which minimizes vehicle delay at signalized intersection, was developed. The developed regression model is implicitly based on the sampled driving practice currently used in Baghdad.The OSCADY/3 software package was used to verify and calibrate the developed model outputs of vehicle delay. The obtained results are presented in this paper. The comparison suggested the existence of harmony between the produced and predicted results. Finally the predicted model is used to evaluate the traffic performance at an existing intersection by simulating its observed data. Based on the obtained results, suggestions were made to reduce vehicle delay at this particular function.