Interaction Of Resource Use And Activities

In conventional Project Management, constraints can be placed on the maximum availability of resources, and these constraints then affect the starting dates of activities, effectively delaying the project due to a lack of resources. For most planning purposes, this is far too crude a control - it is necessary to have some idea what the result of resource use would be before deciding to control it. Orion provides the ability to tentatively make resource bookings, analyse the result, then control those bookings with maximum and minimum constraints, and have the constraints on resource use feed back to control the positioning of activities.









The control of cashflow is a good example of how control of resource use can be used to control activity placement. Each activity carries a usage of cash. The intensity of usage may have a single value, a range, or a number of discrete values (different values for process plant cost, depending on process used). Bookings of these intensities are made, over the possible range of occurrence of the activities. The total range of bookings for each period is accumulated, resulting in a tentative cashflow. Constraints made on the cashflow affect the activities by constraining their range or usage intensity. Putting a maximum limit on the cash in a particular period may push activities away or cut away a particular option if the range of cash usage is made up of a few discrete values. The moved activities will alter their resource bookings, which alters the cashflow, and so on. A deleted cost option may also delete one of the alternative periods for construction, say, tightening the cashflow. Enforcing a minimum limit will make activities draw closer as they pivot around the point of constraint.

The next level of constraint control is to constrain the envelope of cashflow using one of the metrics that reduce cashflow to a single number, such as NPV. Constraining the envelope constrains the cashflow, which constrains the position of activities, or the existence of alternative activities.

Similar tentative booking and then control can be used with risk as the resource.