fast tracking and crashing schedule compression techniques

Today we will discuss fast-tracking vs crashing, the two schedule compression techniques.

There are many reasons why you might need to compress the schedule.

For example, your project is delayed, and you must bring it back on schedule. Perhaps management asks you to compress the schedule, which often happens when your resources are needed for a new opportunity.

Project delays can happen for many reasons:

  • An unrealistic schedule
  • Unavailability of promised resources
  • The occurrence of unidentified risks
  • Force majeure

Other reasons for using schedule compression techniques include:

  • The client wants you to complete the project early.
  • You have an opportunity to get another project if the current one completes early.
  • You want to launch a product early because a competitor has done so.

You can use one of two schedule compression techniques, fast-tracking and crashing, to decrease the project’s duration with no change in scope. 

Fast Tracking Vs Crashing

Let’s start with fast-tracking.


The PMBOK Guide, 6th edition, defines fast-tracking as a schedule compression technique in which activities or phases normally performed in a sequence are done in parallel for at least a portion of their duration.

In fast-tracking, you review the critical path and list all vital activities. Then you analyze and determine which ones can be performed partially or fully parallel with other activities.

You don’t need to review the activities on the non-critical paths, as they have float, sometimes known as slack, the allowable delay before the overall project is affected. Reducing the duration of those activities will not affect the schedule; it will only allow more float to them.

You should monitor other paths whose durations are close to the critical path. If any other path becomes critical, you will need to reduce the duration of the new critical path. In this case, your current path will no longer be critical.

Accordingly, you will then rearrange the fast-tracked activities and reanalyze the schedule.

Project managers start with fast-tracking to compress the schedule because it does not cost more. However, it increases risk as activities overlap.

As a rule of thumb, you can fast-track sequential activities by 33%. This means you can start the next activity when the previous is 66% complete. Both activities partially overlap, increasing the risk but within acceptable limits.

Fast-tracking helps you compress the schedule up to certain limits. Continuing beyond that limit will increase the risk, which may lead to rework and further delays.

fast tracking

Example of Fast-Tracking

Let’s say that you are building a school and the initial construction work is about to finish. Next, you have planned to start carpentry and electrical work.

When you review your progress, you see that you are behind schedule; consequently, you have to move faster to complete the project on time.

You will review the carpentry and electrical work activities and decide if you can perform them in parallel. If so, you can apply fast-tracking.

In this case, you can start the electrical and carpentry work simultaneously, allowing you to speed up the schedule.

Lead Vs Fast-Tracking

On a compressed network diagram, activities with lead and fast-track activities look the same. Hence, many aspirants often think the lead is the same as fast-tracking, but there is a significant difference.

Lead is a type of dependency that you use while developing a network diagram. It is already factored into the schedule. On the other hand, fast-tracking is a forced overlap. You do it to shorten the schedule. Fast-tracking increases risks and potential rework, while lead is a dependency type on the network diagram and does not affect the risk.


The PMBOK Guide, 6th edition, defines crashing as a technique used to shorten the schedule duration for the lowest incremental cost by adding resources.

In crashing, you review the critical path activities and find ones that can be completed early with extra resources, providing the highest compression with the least cost. In other words, you add labor, resources, and anything you can to speed up the process, crashing the activities.

A few examples of crashing techniques are:

  • Overtime
  • More resources
  • Monetary rewards

While crashing, you will monitor other paths as well. It is possible that the duration of other paths could become equal to or greater than your critical path.

Initially, you will get a greater reduction in duration with less input cost. However, as you continue further, the cost will increase, and the reduction will dwindle.

Therefore, do a cost-benefit analysis.

Crashing cannot be applied to all activities. 

For example, you have to wait until the concrete dries before starting your next activity; there’s no way to speed up that process.


Example of Crashing

You are constructing a room. According to the duration estimate, two masons will take four days to complete it.

You can reduce the duration of this activity by crashing, and adding two more masons to complete the task in two days.

Sometimes, crashing may not produce the desired result. Getting skilled resources is not easy, and they take time to settle. You cannot bring in a new group of people and expect them to perform immediately. 

Therefore, it is possible that the cost will increase with no significant gain. Make sure you perform due diligence before crashing to determine if it’s worth the cost.

Difference Between Fast-Tracking and Crashing

The following are a few differences between fast-tracking and crashing:

  • In fast-tracking, activities are rescheduled to be performed partially or fully in parallel, while in crashing, you add extra resources to the activities to finish them early.
  • Fast-tracking does not cost you extra money; crashing does.
  • Fast-tracking increases risks. Crashing does not, significantly.
  • You use fast-tracking when activities can be overlapped to decrease their duration, while you use crashing on those where adding extra resources can decrease their duration.

When Should You Use Fast-Tracking or Crashing?

This depends on your situation and requirements.

For example, if the client wants to complete the project early and is willing to pay, use crashing.

Generally, you will start with fast-tracking to shorten the schedule. If fast-tracking doesn’t yield the desired results, shift to crashing.

Sometimes you may use both techniques. For example, the client is threatening to fine you for the delay. To avoid this, you will compare the cost of crashing with the fine. If the crashing cost outweighs the fine, you will use it with fast-tracking for maximum schedule compression.

You may also use crashing if the project delay will negatively affect the company’s image or credibility.

Why Do You Apply Schedule Compression Techniques to the Critical Path?

As the name suggests, these are schedule compression techniques. The schedule is based on the critical path, the longest path of the network diagram, and its duration is that of the project.

Reducing other paths won’t reduce the duration of your project; it simply gives those paths more float.

If you want to reduce the schedule duration, you have to shorten the duration of the critical path.


Projects often get delayed, and you have to compress the schedule; fast-tracking and crashing are two ways to do that. These schedule compression techniques help you decrease the duration of your project. Fast-tracking does not involve cost, but it does increase risk. Crashing does not significantly increase risk, but it is a costly process. Use these techniques carefully because you are dealing with critical activities. Any wrong step can affect your project negatively.

Schedule compression techniques (Fast-tracking and crashing) are essential techniques in project management. They are also crucial for the PMP exam; therefore, understand these techniques well.

How do you perform fast tracking and crashing in your projects? Please share your thoughts in the comments section.

Fahad Usmani, PMP

I am Mohammad Fahad Usmani, B.E. PMP, PMI-RMP. I have been blogging on project management topics since 2011. To date, thousands of professionals have passed the PMP exam using my resources.