Project Schedule Delays – Causes, How to Prevent and Mitigate

16 min. read

“If you are in the project delivery space, the project schedule delays are inevitable.” Do you agree with this statement? Many of the project managers think that completing projects on time appears only on books. Well, this is not true. With project management office practices, proper project management skills, proactive risk management, and effective planning, project schedule delays can be minimized even if they cannot be lowered to zero.

We will be going over the following in this post:

  • What is project delay?
  • The common causes for schedule delays in projects
  • How to mitigate project schedule delays

Let’s go through each of them one by one.

What is Project Delay?

Before diving into details of schedule delays in projects, let’s describe what the project delay is. There is a magic triangle that is very popular in project management. There are three fundamental aspects or boundaries of each project. These are cost, scope, and schedule.

  • The scope defines what will be delivered throughout the project and the end results of the project.
  • There is a defined budget to complete the project that is planned to be spent throughout the project. You can read more about project cost overruns.
  • The project team works on the project scope and spends the project budget to complete the project on time. The schedule of a project defines the planned dates to complete project activities and the overall project.
Project Schedule Delays
Project Management Triangle

If the planned activities cannot be completed on time in a project, this is called a “delay”. Note that, delays can be on activity level, phase level, or the overall project level. For instance, if one of the project team members is completing an activity in eight days while the planned duration was five days, this is an activity level schedule delay. There can be several phases of a project. If any phase is exceeding the planned deadline, this will be a phase delay. Finally, if the overall project deadline delays, this will be a project schedule delay. Project overruns can be a project as well as non-project related.

Causes for Project Schedule Delays

When we’ve surveyed 425 participants who attended our corporate training programs, 47.2% of the respondents reported that schedule delays are the top project management issue in their organization.

Project-Management-Issues-in-Organizations-1024x527 Project Cost Overruns - Reasons, How to Prevent and Manage


As you can see from the pie chart, schedule delays were the number one issue for their organization for the majority of the project managers. There can be several reasons for a project delay. We will be going over the top five reasons for the project schedule delays.

Causes for Project Schedule Delays #1- Ineffective Scope Management

The project team must gather detailed customer requirements and make the scope as clear as possible. If the scope is not clear, there will be misunderstandings between the customer and the project team. And, this will result in rework and project schedule delays.

How can an unclear scope cause a delay? Let’s understand it a little further. Let’s say, for instance, a customer did not communicate their needs well to the project team. The result of this will be an ambiguous definition of the scope statement. When the product development will start work, there may be some work done based on assumptions. Furthermore, the team might even feel the need to improve the features. Or even add more features to make the product function or look better. Hence, there could be scope creep and gold plating happening also.

It is possible that the customer has communicated clear requirements. However, the project team did not make an effort to write the requirements well and in detail. Resultantly, in the scope statement, there may be more product features written. Or probably some product features weren’t written clearly or in detail. What would happen next is that upon inspection of the deliverables, the customer would detect issues. They would see mismatches between what they wanted and what was delivered. So, they may be requesting rework on some of the deliverables, causing project schedule delays.

As you see, ineffective scope management could easily become the reason for the project delay. Hence, the PMs and their team must ensure that they gather maximum information from the customer and document it well. The project manager then must make sure throughout the project to adhere to the customer requirements. They should understand that unclear scope could decrease the amount of work to be done. Or it could also increase it very much. So, they should not let project schedule delays occur due to ineffective scope management.

Causes for Project Schedule Delays #2 – Unrealistic Activity Estimation

Once you have defined the project scope, now you can define and estimate the project activities. Since the estimation of every single activity can affect the project deadline, you must ensure definitive and realistic activity estimation. If you make unrealistic activity estimations, you will surely witness project schedule delays.

An activity could be done in 10 days, for instance. However you planned it for 20 days, what would be its effect on the project? Well, it will cause the project to finish 10 days later. Imagine then if estimation for several activities isn’t done correctly, how much impact this will have on the project deadline?

In order to estimate activity duration, the scope must be clear. If the scope was not clear but you are an expert in the estimation, your estimations will not help a lot. It’s because when the activity starts, you may have to make scope adjustments. And this may cause some activities to deviate from their plan. Furthermore, the project manager should know how competent their resources are and how productive they are to complete the activities. The PM should also know about the availability of the material and equipment required to complete the activity. Based on all this information, they can then correctly estimate project activities. Furthermore, the project manager should use their expert judgment to estimate the activity and not make assumptions.

The best estimation is often based on past experience of doing a similar activity. However, when you have not done a similar activity before, you could apply various estimation techniques for the activity estimation. Many estimation techniques exist and some are also explained in the PMBOK guide. These include Analogous estimation, Parametric estimation, and Three-point estimation. These estimation techniques save you from having assumption-based estimations and rather having a realistic activity estimation.

Causes for Project Schedule Delays #3 – Improper Risk Management

Every project has a certain level of risk. In fact, every individual project activity may have some level of risk associated with it. If a risk occurs and there is no ready plan to deal with it, you will experience project schedule delays. Depending on the severity of the risk, the delay could be minor but it could also be significant.

However, when you have proper risk management in place, you would look more deeply into risks. You will look at every possible thing or scenario that could cause the delay in the project. You will also ensure that proper risk assessment is done, risk owners are assigned. And that the risk control plan exists and is also implemented well.

Once you have identified the risks, now you should properly assess their probability and impact. If you’ve determined the risk but didn’t understand well the severity of its impact, its planning won’t be worth it. So, it is important to know how vulnerable your project, the IT, and the financial assets are to the risks. And, you should also know what are the chances that the risks will occur and cause any damage. Furthermore, you should also categorize and prioritize the risks to help you focus and manage them well.

Use reserve management to handle project schedule delays

One of the risk management strategies to overcome project schedule delays is reserve management. However, often due to the absence of reserve management project schedule delays occur. If you know that risk could occur and you’re sure that it’ll cause a project delay, you must add a contingency reserve in the project activities. Since the contingency reserve is a pre-approved time to manage the schedule, you can use it anytime without seeking permission. And, delaying the activity, if necessary, within the reserve time won’t be a wrong thing to do at all. And, if you want, you can add the reserve in project phases, or as a whole, in the entire project. So, when a risk occurs, you will utilize the pre-planned reserve to save the project from going past the deadline.

So, in the absence of risk management, risks will occur and you will not be able to handle them well. Therefore, proper and continuous risk management is very important if you want to avoid project schedule delays. It will help you not only in meeting project deadlines but also in fulfilling the project budget.

Causes for Project Schedule Delays #4 – Incompetent Resources

Assigning competent resources for the project activities is crucial. If you assign a junior team member to an activity that requires seniority, what would happen? It is obvious that the activity will take longer to complete. This will then result in project schedule delays.

Assigning an incompetent resource may be good in terms of saving money. However, your project activities may end up delaying just because of them. A resource who is incompetent to do a particular job may be too slow than expected in completing the activity. Or probably they do not have enough skills to produce the deliverables as you expect, causing the need to rework.

We know that a project often consists of hundreds or thousands of activities. You can imagine then how much collective delay incompetent resources could cause to these activities. Competent resources on the other hand have many advantages. They are not only good for completing the activities, but they can also focus to achieve the project objectives. They also aim to work faster, reduce waste and incorporate their creativity to achieve the best results.

Therefore, the project manager should carefully assess the technical and non-technical requirements of the project activities. And, make sure to assign competent resources to get the job done. The Project Manager Officer leading the PMO of an organization must facilitate collaboration, knowledge sharing, and a servant leadership environment to maximize project management efficiency in the organization.

Causes for Project Schedule Delays #5 – Gold Plating

Gold plating is a project management term. It is defined as “doing more work than what is required”. In some cases, project resources continue to add on new functions or features. Or they try to do more although their activity has finished for a particular task. This causes project schedule delays. Project management is all about delivering a defined scope, within a defined budget and schedule. Not, delivering more than the agreed scope.

Gold Plating may be good for the customer as they would be getting additional things for free. However, it would cost the project more. In some cases, the customer does not like to get additional features. So, they may not be happy with the extra effort that you have made.

The project team gold plates with good intentions, which are obviously to please the customer more. And, sometimes, the project manager adds extra features to earn credit. Or, they may want it done to divert customer’s attention from defects or to prove their team’s ability. However, it may backfire. In either case, whether the customer likes gold plated outcomes or not, you will face project schedule delays. Not just this, you will incur more cost on the project as well.

How to Mitigate Project Schedule Delays?

There are 5 fundamental ways to mitigate the project schedule delays and we explain them in detail below.

1-) Make Project Scope Clear

If the scope isn’t clear, there may be mismatches between what you’ve delivered and what the customer had actually wanted. If there are mismatches, the rework activities will cause project schedule delays. So, for the scope to be clear, we should, first of all, make sure to collect customer’s requirements thoroughly.

When interacting with the customer, you must make sure to ask as many questions as possible. Try to get maximum information until the customer confirms that you have understood exactly what they want. Do not make any assumptions and rely on them! The next step is to define a clear project scope. The scope includes the acceptance criteria, constraints, exclusions, and the detail of the deliverables needed. It also includes a description of the work needed to produce the required deliverables. Hence, defining a perfect scope, which is also clear, unambiguous, and complete is very important. It not only helps stay on the schedule, but it also helps you run the project smoothly.

2-) Acquire Competent Resources

Competent resources will make realistic estimations and complete the activities as much on time as possible. Competent resources will focus on project goals and make sure they are working towards the goal. They will be more productive and more resilient to stressful situations. They will demonstrate creativity and resolve problems quickly. Furthermore, with basic project management knowledge that they may possess, they would have the ability to work through the plans.

Hence, having competent resources will help in completing the project work as planned and also preventing hindrances on the way. Thus, the project manager must know the level of competency required on the project activities and acquire the resources accordingly. Competent resources will prove to be very helpful in meeting the project deadlines and preventing project schedule delays.

3-) Effective Change Management

Effective change management is necessary to ensure a consistent, measurable, and structured environment to deal with the change requests. Your organization should have a document that defines the procedure and the workflow for effective change management. And, the PM should ensure that every change request should go through proper change management.

After you have finalized the scope, you must manage every new requirement through change management. During project execution, there is often a need to make changes. Anyone may request changes such as project resources, the project manager, sponsor, or the customer itself. The project manager, along with other key stakeholders should assess the change requests. They should evaluate the effect of the changes and also understand what is the effect if these changes do not go live. Any change that you do not properly assess and the one that is not beneficial must not be authorized. If you authorize such a change, its implementation will unnecessarily consume project time and cause project schedule delays.

Once the project manager has assessed the change request, they must inform the sponsor and the customer. They should inform them on how the change will affect the project budget and the schedule. Also, they must take the sponsor’s and the customer’s approval before allowing their team to work on the change. If effective change management is not in place, the project may face many problems in its completion. And there could be many schedule delays.

4-) Accommodate Risks’ Schedule Effect

When a risk occurs in a project, there will be two effects to the project immediately. It will require a budget and you will also need time to overcome the effect. Therefore, risk management must ensure that schedule buffers exist for the probable risks that can affect the project schedule.

During the project planning phase, the PM should determine the right amount of buffers to include in the project schedule. The buffers required should be based on a thorough risk assessment and not assumptions. And, during the execution phase, if a risk does occur and an activity delays, only the buffer should be consumed. Time consumed outside the buffer will delay the project, hence doing this must be avoided.

5-) Take Schedule Baselines and Do Periodic Baseline Assessments

Once you have developed the project schedule baselines, these will help in comparing the actual progress with the planned schedule. To know whether you are going ahead of schedule or behind the schedule, look at the schedule baseline. Also, look at the actual progress information.

When comparing the schedule baseline with the actual project progress, if you find a delay, you should take an action. And, if the project has already consumed buffers, then you must act immediately. You should do something to not let the project delay further and bring the project back on track. Therefore, it’s important for the project manager to be knowledgeable of various project management techniques to fix the project delay.

For example, when there is a delay, the PM could add more resources to the remaining work. Or make the existing resources work overtime to finish the task earlier. Or, they may reduce any lag between the activities or make them start in parallel. They could even turn on some weekends to give extra days to the project. By reducing the duration of some of the activities, they can also compress the schedule. What if you have looked at all these options and still couldn’t compress the schedule enough? In that case, you may even remove some activities from the project. You may find some activities which you think you could still manage without them.

When the project schedule delays, the PM should determine the best option to mitigate the effect of the delay. It is possible during baseline assessment that you figure out that no option to remove the delay is currently suitable. In this case, you may then request the management to allow the use of the management reserve. But, this should be your last resort to fix the project schedule delays.

Summary: Project schedule delays

Project schedule delays have a very negative effect on clients, consultants, and contractors. They lose trust in you. And they do not look at you with confidence in terms of future relationships and business growth. Not just this, even the project resources may lose their morale. When they see the project going into trouble, they think that putting full effort into it wouldn’t be worth it. Since the project will fail in terms of schedule anyway, they don’t give much attention to it.

PMI Pulse of the Profession conducted a survey in 2018. According to the survey, just 52% of the projects worldwide could complete on time. This is a shocking figure indeed. But, it is actually the bitter truth that most of the projects face delays. Whether it is an IT project, Civil, Mechanical, or any other project, schedule delays will be there.

One delayed project may be acceptable but when several projects start to delay, there will be unacceptable or irreversible consequences. So, it is ultimately the responsibility of the project manager to try to avoid the project schedule delays. Or if they can’t be avoided, at least the effects should be mitigated. And for the PM to do so, they should have effective reserve management. Moreover, they should have competent resources in the project. Their activity estimation should be correct and there must also be effective risk management in place.

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