Resource Management

Resource management assigns limited resources to project activities while preserving precedence relationships and the required project completion date.

The project network supplies the durations, earliest times, latest times, and floats used in the schedule.

Three Different Tasks

Use the methods in this order.

1. Schedule activities at their earliest feasible starts.
2. Calculate resource demand in every interval.
3. Level the schedule if demand exceeds capacity.
4. Smooth the feasible schedule if peaks and idle periods remain.

Resource Profile

For resource $r$, the demand in time period $t$ is

Create the profile by splitting the timeline at every activity start and finish. Add the resources of the activities running in each interval.

An activity contributes from its start up to, but not including, its finish. A dummy activity contributes $0$ resources.

Scheduling

1. List every activity, duration, predecessor, and resource requirement.
2. Apply the forward and backward passes to the project network.
3. Place every activity at its earliest start.
4. Calculate the resource profile.
5. Compare every demand with the available capacity.

Activities with positive total float are candidates for movement. Critical activities have zero total float and normally remain fixed.

Leveling

Leveling removes over-allocation. The resource capacity is a ceiling that no interval may cross.

Quick Leveling Method

1. Find the first interval where demand exceeds capacity.
2. List the activities running in that interval.
3. Remove critical activities from the candidate list.
4. Choose a candidate with enough float to move.
5. Prefer the move that removes the most excess with the least loss of float.
6. Move the activity to its latest feasible start.
7. Recalculate the affected intervals.
8. Repeat until no interval exceeds capacity.

Check these 3 conditions after every move.

• Precedence
  Every predecessor still finishes before the activity starts.
• Capacity
  No resource demand exceeds its available capacity.
• Completion
  The new project finish is recorded.

Leveling may extend the project when available float is insufficient. A move within existing float does not extend the project.

Smoothing

Smoothing reduces variation in a schedule that already satisfies capacity. It does not change activity durations, precedence relationships, or the project completion date.

Think of the resource profile as bars.

• Leveling removes bars above a fixed ceiling.
• Smoothing moves bars away from peaks and into valleys.

The goal is not a perfectly constant profile. The goal is fewer avoidable peaks and idle intervals.

Quick Smoothing Method

1. Start with a feasible, leveled schedule.
2. Find a high-demand interval and a nearby low-demand interval.
3. Find an activity crossing the high-demand interval with positive float.
4. Shift it toward the low-demand interval.
5. Keep the shift if the project finish is unchanged and the profile improves.
6. Repeat until no useful shift remains.

Worked Example

Resource $R$ has a capacity of $3$ units per time period.

The project duration is $12$. The critical path is $B \to E \to G$.

Prepare the earliest-start schedule. Level the resource use. Then smooth the leveled schedule.