This paper reports a library research which investigated the way decisions of early start or late start schedules are applied in the MS Project. The problem intended to solve or clarify is whether literature holds the scenarios where options of early or late start schedules may show superior schedule performance. It is noted that key scheduling processes and procedures such as choice of early start schedule and late start schedule will significantly impact project performance. This literature search proposed answer to the question: How can the planner make better scheduling decisions and explore relative benefits of alternative options? It shows that project performance evaluation results may provide evidence that some choice influence schedule variability which in turn, is strongly and positively correlated to productivity. It is imperative for contractors to continually monitor the scheduling practices adopted, the choice made when the schedule is developed and relate these to project performance in order to identify particularly effective scheduling practices for use in scheduling future projects. Strong argument is developed from literature that if network scheduling methods fail to address the issue of start time constraints for various project tasks, it is likely that the schedules generated will be inaccurate. This is because changes in the schedule are inevitable occurrences in construction projects. The causes of such changes are numerous and well catalogued in the literature: weather, owner-directed changes, information request and information release problems, period for approval of submittals, unexpected soil conditions, long lead supply items, delays, accelerations, and rework that affects schedule coordination difficulties. Such changes are challenging and difficult to proactively accommodate in the initial schedule development because they affect multiple activities, often leading to disruption of activity start dates of succeeding tasks. It is therefore important to satisfy practical scheduling requirements, such as scheduling an activity to start only when all information requests, all prerequisite work and materials required for its commencement are available. The paper concludes that a good understanding of the tasks affected by these listed delay causes is important so that a right choice of start date is made to proactively nip the delay situation at the bud. If disruption of activity start is reduced to zero particularly for the critical activities, then the project may finish on the due date, with optimum overall project cost.
Keywords: Construction Scheduling, Decisions, MS Project, Optimism, Pessimism, Project Calendars