One of the known reasons for construction projects failure is missing to achieve the target work at the time specified in the scheduled time of baseline , and this can be caused because of the fragility of creating of the schedule time plan of the project, because of determination a particular time period for each part of the project that far a way and less than reality. And this attributed to eliminating weather changing effects on labors in site. So, according to these Effects, we concentrated in this book on measuring the shortage in amount of work done by labours to help submitting realistic schedule plan.