Avoiding Project Schedule Slippage

A classic quotation from the world of project management is the question ‘how does a project get to be a year late?’ And the answer is one day at a time.

Think back to your own experience, if you have heard of a project that came in late or overspent, can you honestly say that it was due to some major catastrophe, or was it more likely to have been the end result of many small daily slippages?

From my own experience, whenever a major problem occurs on the project, it gets to meet you to focus attention and resources are firmly applied to resolve the problem and get back on track. The project manager and the team stepped up a gear and resolved the problem.

The daily slippages or more importantly their consequences seem to slip by unnoticed. If a meeting needed to be postponed for whatever reason, or materials were delayed in arriving to the team, or someone got sick for a few days, or the customer requested an urgent meeting with the project manager, ect….

It is precisely for these facts that such day by day slippage is harder to predict and prevent and seemingly harder to catch up, and that three key approaches are required to minimize and keep such situations under better control:

project schedule slippage

Understand and apply the technique of critical path analysis.

This is not hard to understand nor apply, particularly as these days, there are excellent software management tools freely available to help identify and apply the use of critical path to a given project.

The critical path schedule of activities shows clearly those tasks that if they were to slip, that this delay will have the same effect on the project end-date and/or key milestones. These are called critical activities. Critical path will also identify those activities whose duration can extend by some amount or that their start and end dates can slip – without creating any delay to the project end-date.

The corollary of this is of tremendous importance, since it allows the project manager to focus on putting their best people and priority on critical tasks, while assigning resources that are still developing those skills for example, on non-critical activities.

Just applying this one technique will allow the project manager throughout the whole of the project, to quickly identify where daily slippages will have an impact on the project delivery, and give the project manager the relevant information to determine actual progress and future forecast. Knowing today that if we keep doing what we are currently doing will result in future slippage, allows the project manager to take timely corrective action.

Having a schedule.

And this ties in to my critical path comments above. But I am referring here to identifying clear products or deliverables that need to be created throughout the project. Do not confuse products or deliverables such as ‘completed help desk’ with the activities – which are typically stated as ‘build new power supply’.

The key dates that such deliverables or products needs to be created, can be seen as milestones within the project schedule. But there will be other milestones as well. An example here would be an important date that they demonstration or a meeting needs to occur on.

Such milestones in the schedule must be concrete well defined and specific measurable events. A milestone is defined as a zero duration task.

Blame Culture.

The third approach is possibly harder to implement because it refers to the human condition! Let me explain. If your organisational culture tends to be a blame culture, such that any errors by others is seen as a failure, then it will cause everyone within the organization to take a protective stance on everything they do.

So what does this mean to the project manager? It probably means that if your team notices a small slippage, their instinct is to hope that they can fix it themselves without communicating it up to you. Clearly there is a balance here in ensuring that individuals take responsibility for their actions and don’t feel the need to escalate every small thing as this would be likely to overwhelm the project manager and distract them from managing and controlling the project.

The solution here is to make it clear from the very beginning of the project that sharing of information is to be encouraged and that problem-solving is an admirable trait! Another is to set up regular reviews reports and audits that encourage giving honest and timely information so that swift corrective action can be applied.

One of the fundamental approaches when confronted with a delay, is to throw more resources at the problem, but simple studies have shown that as a general rule, doubling the resources will only increase the task duration by a third.

Brooks’s Law states that when adding another member to an existing team then communication effort needs to increase, and this will include aspects such as familiarisation with the work involved and training. In short a new team member needs to be ‘bedded in’. The communication effort between that new individual and all other individuals within the team can be significant.

In summary, adding extra resources will quickly reach a point where it ceases to have any value. Of course, here I am referring to human resources as adding extra tools for example can directly increase productivity.

Establish the root cause

Like any aspect of problem-solving, the first step should not be add extra resources, but first identify the root cause of why slippage is or has been occurring. You will want to know WHY first, before considering what best corrective action to take. Here are some questions to consider asking:

Are the activity deliverables clear to all concerned?

This in and of itself should demonstrate the benefits of first identifying the products and deliverables within a plan before identifying the activities and resources. Suppose you have a product called new Power Supply. As much information as possible relating to the Power Supply must be documented. Key information is the quality or acceptance criteria upon which successful completion of the Power Supply can be determined. Other aspects are resource information needed, the way in which the work should be carried out, tools/standards to be used, and any dependencies human or otherwise, that will lead to successful completion of the Power Supply.

This has a surprising side effect. When people have clarity in the outcome of any task or activity, then they are motivated and work far more efficiently.

Leadership and motivation.

The project manager must take the lead here and ensure that all members of the team are committed to the success of the project, not just by telling them that, but by demonstrating on a regular basis. An excellent way of ensuring all the team are committed is to make sure they are fully involved in the planning aspects of the project. If they are ‘in at the birth’, they will take more interest and responsibility in nurturing their responsibilities within the project to a successful conclusion.

Realistic and achievable targets.

The use of planning workshops where all key stakeholders are involved is a powerful tool to ensure that accurate, realistic and achievable estimates are arrived at.

By realistic I mean that the number of team members can be obtained, and that their knowledge skills and experience had been taken into consideration when establishing such estimates.

Rewards and individual value.

There is a famous book called ‘the 1 minute manager’ written by Dr Kenneth Blanchard, and this describes the excellent management practice of not only acknowledging shortfalls in performance or results by both directly acknowledging and supporting its resolution, but equally keeping an eye open for when an individual performs good work and going on to openly acknowledge it.

You will notice enthusiasm amongst the team builds fast if you carry this out because if an individual does not get praise for doing a job well, then why would they be motivated or enthusiastic about their work within the project. Rewarding them does not have to be financial for them to feel valued.


As part of planning, the project manager should identify the knowledge skills and experience needed for the team that is to work on the project. However, in the real world is may be that the project manager has to accept less experienced staff. Unless this is funded separately, then the project manager should build a training budget into the project as this will save money by preventing expensive reworked or errors throughout the project. In a similar way, training can fix slippage if given promptly.


I’m ‘old school’ on this topic as I believe that an individual works most efficiently and effectively when doing one thing at a time, even though many organisational cultures seem to praise those who multiplex and interleave many of their task responsibilities on a regular basis. One thing is for sure however, and that is that part time teams are used on your project and therefore have to share their time. This should be factored in when making initial estimates and balancing the work effort required against the actual duration such an activity will take. If slippage occurs, consider negotiating for an individual to be full-time on your project – even if only for an agreed period.


It is sometimes necessary particularly when knowledge skills and experience neither exist nor are available, that some of the project work needs to be sub contracted out to a third party. Again, be aware that subcontracting does produce extra management and communication overhead. Whether this is planned in from the start or not, subcontracting can be used where slippage is occurring. If work is subcontracted to a specialist department, group or organisation then they can often create the products in a more efficient manner because that is their specialism.

Work scope.

When defining the project scope (scope means what is included within a project and what is not included, with the focus of a clearly understand the project boundaries), then a potential technique to reduce slippage, is to reduce the project scope and hence the work needed.

This may refer to reducing functionality of a particular product, or relaxing the standards or quality criteria, or it may be to remove the need for one or more products within the main project deliverable. Sometimes discussions with the user or customer about which products or deliverables are ‘must haves’ and which are ‘nice to haves’can be a usefull start to agreeing scope reduction.

Change control.

As part of creating the project plan, an agreed approach and system for managing changes’ must be set up. A key part of this is the agreement that once a plan has been sign-off that any changes to it can only occur when given by the appropriate authority.

In addition, the change process must include a step that examines the impact across the whole of the project to any requested change, considers options to implement such a change, and only then seek authorisation from the appropriate individual.

The project manager must therefore keep a close eye to ensure that changes are not appearing too frequently, as this is a clue that something is out of control. Sources to check here are that are the requirements are sufficiently understood, have the right individuals been involved in agreeing the project deliverables, or that is the end deliverable of the project to be implemented within a dynamic operational environment. In other words is the operational use of the end-product highly likely to change throughout the duration of the project. The customer must be made aware of time and budget consequences when requesting changes to what was originally agreed.

Finally I would like to acknowledge the benefits of a particular approach to project management which has been called ‘management by walking about’. What this rather humorous phrase refers to, is that a manager should not just rely on the more formal sources of project progress such as emails and reports, but should get off their rear ends and talk to the team. This should be done informally and will give many of the leadership and morale boosting points I have made above as well as discussing team problems and fostering cooperation between all those involved.

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David spent 25 years as a senior project manager for US multinationals and now develops a wide range of project-related downloadable video training products under the Primer brand. In addition, David runs training seminars across the world, and is a prolific writer on the many topics of project management. He currently lives in Spain with his wife Jude.