The fair prediction of completion time of the road project at the initial stage is crucial for the preparation of the tenders. Usually, the engineers using their past experience to assign inaccurate execution time for this type of projects which are not supported by any statistical models. This paper aims to find an acceptable mathematical model that helps specialists in road projects to estimate the implementation time in a more realistic way. Two mathematical models have been developed, which can effectively predict the execution time of road projects in Iraq based on quantities of each of base layer length, width, earthwork, sub base and final cost of the road project. The test results of the nonlinear regression model (NLRM) seem to be more accurate than multi linear regression model (MLRM). NLRM coefficient of determination (R2) is 88.6%, while 76% for MLRM. The mean absolute percentage error (MAPE) 20.29%, 11.65% for MLRM and NLRM respectively. The root means square errors (RMSE) are 76.59, 45.73, and the average accuracy percentages are (AA) 79.71%, 88.35% for MLRM and NLRM respectively. The developed NLRM model reinforces the ability of the decision maker in such projects to accurately estimate the required time pre tendering process.