The objective of this research is to develop the model for construction time prediction of asphaltic roads during the planning stage. The model is developed by determining factors influencing time duration of critical activities and their sequential lag times. The data of forty completed highway projects during 1992-1997 are collected from the Department of Highways. Using a multiple regression method, the time prediction equations of all critical activities including preparation, earthwork, subbase, base, incidental and lag times are developed. The total project duration can be estimated using the Critical Path Method (CPM) by summing the predicted times of the activities which are on the critical path. The errors from the prediction model when compared to the actual construction time of the forty incorporated projects and seven other projects are ±8% and ±13% respectively. These errors are less than the errors from the traditional estimation method, which is estimated based on the productivities of construction machines. The estimation time from the prediction model is also highly correlated with the actual time; the correlation coefficient is equal to 0.956. As a result, the model can be used to reasonably estimate the construction duration of asphaltic roads. Furthermore, the major influencing variables on activity duration and lag time are determined in order to increase awareness when using the time prediction model.
