Once the variances from project goals are quantified and their responsibilities assigned, informed team decisions may be made and the necessary management support provided to mitigate the impact. Time is of the essence in engineering and construction, and, therefore, for the decision-making process. The importance of quick and early action should be obvious. Changes to scope made at the start of a project phase can generally be accommodated with the least cost and time impact.

As discussed in the Project Management Module for the three project goals of scope, cost, and schedule, a change in one will impact at least one of the others. Therefore, it is important to prioritize the goals at the start of a project. Effective control of scope changes, adequate budget contingency, and baseline schedule "total float" (time allowed for a task to slip behind without impacting the completion date) are essential in reducing the variances of the three goals. Project scope and cost attenuation methods were discussed in the previous section. The means and methods are the remaining issues that impact schedules.

Maintaining the Schedule

Early and continuous planning and scheduling of a project allows for prompt detection of schedule impacts with sufficient time to explore a range of options to maintain the schedule. Scheduling the project from beginning to end provides the benefits of expending resources early to stay on or ahead of schedule. This avoids expending even greater staffing resources at the end of the project, trying to catch up.

As an example of resource options, Figure 5 shows a sequential or finish-to- start (i.e., finish the entire preceding task before starting the next) schedule that satisfies the contract duration. However, you should realize that this is not the typical way the project is to be built. It is essential that the work is broken into tasks of reasonable work-day duration. 15-day tasks, in this example, are difficult to manage unless subdivided into smaller tasks. A sequential plan often does not provide adequate flexibility to respond to delays. By subdividing the activities into concurrent (those that may occur simultaneously) tasks, the work can be completed in a shorter time with the same total resources. Figure 6, shows a possible approach, given manpower availability. The critical activities are connected by logical constraints and durations. A delay in one activity will delay the project completion date. The critical (longest) path is determined by summing up the longest activities for each sequence below. In essence, because of the shorter overall duration, Figure 6 builds in "total float" (the schedule equivalent of budget contingency) to the contract completion date, thereby providing for potential disruptions. This shows that projects can also be accelerated by re-sequencing, as well as the obvious method of providing additional resources to reduce critical path durations.