Most projects have a specific finish date, budget, and scope. This trio of time, money, and scope (which is defined as the combination of all project goals and tasks, and the work required to complete them) is often referred to as the "project triangle." If you adjust any one of these elements, the other two are affected. While all three elements are important, typically one will have the most influence on your project.

For example, if you decide to adjust the project plan to shorten the schedule, you might end up with increased costs and decreased scope. If you need to adjust the plan to meet the project budget, the result might be a longer schedule and a decreased scope. Or, if you want to increase scope, your project might take more time and cost more money.

The ways that changes to your plan affect the other two sides of the triangle vary, depending on your specific circumstances and the nature of your projects. In some instances, shortening your schedule might increase costs. In other instances, it might actually decrease costs.

Working with the project triangle

As you create or modify your project plan, you might find that it no longer meets important goals. For example, your plan might show the project finishing too late or going over budget. You'll need to optimize your plan to get it back on track. When you begin optimizing, first determine whether time, money, or scope is most important to the success of your project. In other words, which problem do you need to solve first?

• My project's taking too long.
• My project or tasks are costing too much.
• We're trying to do too much, or we're doing too little.

When you begin to optimize your plan, keep the three elements of the project triangle in mind. Remember that when you adjust one side of the triangle, the other two sides will be affected, either positively or negatively, depending on the nature of your project. Check the other two elements of the triangle to be sure your adjustment hasn't made your project plan unworkable. For example, if you adjusted your plan to reduce costs, check to see if your finish date is still within acceptable limits.

The time side

After some analysis, you might determine that your schedule does not meet the project deadline. There are several ways you can adjust the length of your schedule. The methods you choose depend on the limitations imposed on the project as a whole – such as budget, resource, and scope constraints – and the flexibility of the tasks.

The most efficient way to shorten the schedule is to change the tasks that must be completed on schedule in order for the project to finish on schedule. Such critical tasks make up what is called the critical path. Modifying tasks that are not on the critical path may not affect the schedule. You can:

• Shorten the durations of tasks.
• Overlap tasks if they can be worked on simultaneously.
• Assign additional resources.
• Decrease the amount of work assigned.

As you adjust the schedule, your costs might increase, resources might become overallocated, and your scope might change. For example, if you shorten durations of tasks on the critical path, the project will probably finish sooner, but the scope of those tasks – and possibly the entire project – might be reduced. Or, if you assign additional resources to critical path tasks so that they can be finished more quickly, you might find that these resources are now overallocated and you need to pay overtime, increasing your costs.

The cost side

You might find that the project plan you have built exceeds your budget. Resources, which are the people, equipment, and material assigned to the tasks in the project, are the primary factors that affect project costs. These costs are usually a combination of rate-based costs and fixed costs.

To reduce costs, you can cut project scope so that there are fewer tasks or shorter durations for tasks that need resources.

You can also adjust resources and make sure that your settings for rates, fees, and overtime are correct. You can verify that the resources assigned are the best for the job. You might be able to replace a more expensive resource with a less expensive one, and use the more expensive resource where it is most cost-effective.

As you adjust the plan to meet your budget, your finish date might be extended or your scope might decrease. For example, if you remove overtime from tasks that had overallocated resources assigned, you might find the schedule lengthened, pushing the finish date to later. Or, if you've cut scope to meet the budget, you might find that the finish date is actually scheduled to occur sooner.

The scope side

Typically, you adjust scope when you find a problem with meeting the finish date or the budget. You can cut scope to shorten the schedule or cut costs. You can also increase scope if you find you have additional time or budget available.

Changing scope typically involves changing the number or the duration of tasks. Scope is closely related to quality. When you decrease scope, you might need to lower standards of acceptable quality.

If you cut scope, your costs might decrease and your projects might be scheduled to finish sooner. If you add scope, your costs might increase and your finish date might be later. For example, if you cut a series of tasks that were considered optional, the resources assigned to those tasks are now freed up to work on other projects and are not being paid from this project's budget. Or, if you're increasing scope by adding more time to a series of tasks, you might find that changing scope affects the scheduling of critical path tasks, and the finish date is later.

Where resources fit into the project triangle

Sometimes you need to optimize your project plan to make sure your resources are being used efficiently, with a reasonable, balanced workload. In terms of the project triangle, resources are considered a cost. So, as you adjust resources for more or less work or availability, your costs go up or down correspondingly, based on resource rates.

However, as you adjust resources, your schedule might change. To resolve resource conflicts, you might decide to split one or more tasks. A split task is one that is interrupted in the course of its completion, to be resumed sometime later when resources are once again available. You could also include delays. A delay is the amount of time between the scheduled start of a task and the time when work actually begins on a task. For example, if you have a number of resource overallocations and you resolve them by delaying or splitting certain tasks ? a process called leveling the project ? the schedule might now have an extended finish date. Or, if you have a resource underallocation (resources assigned to work fewer hours than they are available), you might increase the scope of a series of tasks to use the resource's available time.

The quality angle

Quality, a fourth element, is at the center of the project triangle. Changes you make to any of the three sides of the triangle are likely to affect quality. Quality is not a side of the triangle; it is a result of what you do with time, money, and scope.

For example, if you find you have additional time in your schedule, you might be able to increase scope by adding tasks and duration. With this extra time and scope, you can build a higher level of quality into the project and its deliverables.

Or, if you need to cut costs to meet your budget, you might have to decrease scope by cutting tasks or reducing task durations. With decreased scope, there might be fewer opportunities to achieve a certain level of quality, so lower quality may result from the need to cut costs.