The final two planning tasks for a project are resource and cost scheduling. This process uses the resource schedule to assign time-phased costs that provide the project budget baseline. Project scheduling system should address the following questions:
• Will the assigned labor and/or equipment be adequate and available to deal with my project? • Will outside contractors have to be used?
• Do unforeseen resource dependencies exist? Is there a new critical path?
• How much flexibility do we have in using resources?
• Is the original deadline realistic?
If resources are not adequate to meet demands, the late start of some activities must be delayed, and the duration of the project may be increased. This process is called resource-constrained scheduling. Also, it may be desirable to even out resource demand by delaying noncritical activities (using slack) to lower peak demand and, in such way, increase resource utilization. The schedule network diagram assumes the resources in terms of labor and equipment are available to perform the required work, which is often not the case. Parallel activities hold potential for resource conflicts. For example, we may schedule some activities at the same time that would altogether require more resources than available which then need to be reassessed and delayed if necessary changing the schedule network and critical path which can make the project more or less sensitive depending on whether now there are more activities on the critical path or less in comparison to before the reassessing (leveling) was conducted. This approach is using heuristics to resolve the resource constraint problem. Heuristics allocate resources to activities to minimize project delay. The parallel method is the most widely used approach to apply heuristics. The parallel method is process that starts from the beginning of project time and, when resources needed exceed the resources available, retains activities first by the priority rules: 1. Minimum slack. 2. Smallest duration. 3. Lowest activity identification number.
The activities able to be scheduled without delaying others are pushed out farther in time. When a resource limit has been reached, the early start (ES) for succeeding activities not yet in the schedule will be delayed and their slack reduced. Like leveling schedules, the limited resource schedule usually reduces slack, reduces flexibility by using slack to ensure delay is minimized, and increases the number of critical and near-critical activities. Once resource assignments have been finalized project management is able to develop a baseline budget schedule for the project. Using the project schedule, they can time-phase work packages and assign them to their respective scheduled activities to develop a budget schedule over the life of the entire project. Although there are several types of project costs, the cost baseline is usually limited to direct costs (such as labor, materials, equipment) that are under the control of the project manager.
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