Reducing the lead time of construction projects is a great challenge in today's competitive world and especially where the LD (Liquidated Damage) is high. The duration is commonly lengthened due to high dependencies among activities/parties. Greater concurrency can shorten project duration and this can be achieved by getting early information from precedent activities especially in the design phase. The concept of using early estimated information is found to be useful in reducing the duration of the design project. However, this concept imposes rework for successor(s) if there is mismatch between used estimated information and the original information that comes from full analysis. On project completion, the impact of rework due to the use of early estimated information is of great concern. Therefore, this study examines the benefit from early information through estimation and the adverse effect of rework. In the design process, some activities are estimable while some are not. Moreover, most of the events are stochastic in nature including the probabilistic nature of the activity durations and potentials for rework. For this reason, in order to validate the abovementioned concept, the simulation technique has been utilized to model the design process.