Everything You Need to Know about S Curves in Construction

As a construction project manager, you're responsible for monitoring all aspects of your project from the commencement until its completion. One of the most valuable tools in your toolkit is the S curve. S curves are a graph of a project's performance over a period of time, and are critical for successful project management.

In this article, we'll be covering 10 things you need to know about S curves for construction project management, from an explanation of what an S curve is and how to make one, to how to analyze them and leverage them for bettering your project management skills.

Once you read this article, you'll have a firm grasp of how S curves can assist you with cost control, managing your time, monitoring your project, and more, and how you can use those knowledge gains in your construction projects. Let's dive in!

Understanding S curves

Before we move to the 10 things you must know about S curves for construction project management, we first need to examine what an S curve is and why it matters. Simply put, an S curve is a graph of a project's development over a period of time, with the x-axis as the axis for time and the project performance as the axis for the y-axis.

The S curve itself is known as an S curve because, when graphed, it typically forms an S shape. S curves are critical when it comes to construction project management for a number of reasons:

• Cost control: By monitoring your project's performance over a period of time, you can spot any over-runs or under-runs in your costs early and act to fix them before it's too late.
• Time management: S curves can be used to monitor your project's schedule and make certain you're on a schedule to hit your deadlines.
• Resources allocation: S curves can be used to allocate resources properly, by monitoring when and where you need resources during the project.

By combining S curves with other tools you use for project management, you'll be able to get a fuller picture of your project's performance and make certain that it stays on course from the very beginning through the very end.

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Creating S curves

Making S curves for your construction project may look intimidating at first, but it's a fairly straightforward process once you've mastered the basics. The following are the steps to make S curves for your project:

• Define your project scope: First, you need to define your project scope. This means you need to identify the most critical deliverables, milestones, and deadlines.
• Gather your data: To make an S curve, you need to gather information about your project's performance over a period of time. This can be information about the amount of money, the amount of time, and the amount of resources used. The most effective teams get this directly from their site diary.
• Graph the data: Once you've got your figures, you can draw them onto a graph, with your timeline down the x axis and your performance up the y axis. Use software tools such as Microsoft Excel or project management software to draw your S curves.
• Customize the S curve: You will need to customize your S curve depending on the particular details of your project. For instance, you might need to draw different S curves for different project phases or for different resource types.
• Update the S curve regularly: To maximize the usefulness of your S curves, you will need to update them periodically with current project information. This will enable you to monitor the progress of your project over time and make any required adjustments.

By following these steps, you can draw S curves which give you a precise and realistic snapshot of the progress of your project, and help you keep direction throughout the construction process.

Analysing S curves

Just drawing S curves is half the process when it comes to effective construction project management. The second part is to analyse them and use them for monitoring project performance. Here are a few things which you need to keep in mind when you are analysing S curves:

• Look for trends: S curves will help you spot trends in the performance of your project over the passage of time. For instance, if the curve is becoming flat, you can be certain that the project is slowing down or is running late.
• Identify impending problems: Through the analysis of S curves, you can spot impending problems and address them. For instance, if the trend for the cost curve is increasing above forecast, it can be a sign that you need to make a change to your budget or redistribute resources.
• Use the curves to make forecasts: S curves can also be used to make forecasts for your project's future performance. For instance, if the cost curve lies below the planned curve, it can be a sign that you are likely to fall within your budget.
• Compare actual performance with planned performance: S curves can be used to compare actual project performance and planned performance, and to see which areas you are under-performing or over-performing.

By regularly monitoring S curves and making adjustments to your project plan based on the knowledge you gain, you can ensure you are on course and deliver a successful construction project.

Using S curves with Earned Value Management

S curves are a valuable resource for monitoring project performance, and are even more useful when used together with Earned Value Management (EVM). EVM is a project management methodology that combines cost, schedule, and performance measures to gauge project completion and make forecasts of future performance. When you use S curves with EVM, you can learn even more from your construction project. Here is how you can use S curves with EVM:

• Calculate the Earned Value: To compute the earned value, you must calculate the budgeted cost of work performed (BCWP). This is the actual budget for the amount of work that's been carried out. For instance, if your budget for a certain task is £10,000 and you've carried out 50% of the task, the earned value would be £5,000.
• Compare the earned value with the actual cost: Once you've worked out the Earned Value, you can then compare it with the actual cost of the amount of work carried out (ACWP). This will inform you whether you are over or under spending, and uncover any potential problems.
• Use S curves to visualize performance: S curves help you visualize how your project is performing against the planned schedule and budget. You can get an even clearer picture of your project's performance by comparing your S curves with the earned value figures.
• Calculate essential EVM measures: With S curves alongside EVM, you can calculate essential measures such as the cost variance (CV), schedule variance (SV), and cost performance index (CPI). Using these measures, you'll have a precise understanding of the way your project is performing and whether you need to implement changes to keep your project on course.

By employing S curves alongside EVM, you can gain a richer appreciation for your construction project's performance and make evidence-based decisions to ensure a positive result.

Common Mistakes to Avoid

Although S curves are a formidable construction project management tool, there are certain traps you can fall into and reduce their usefulness. Some of the most frequent mistakes you can make when using S curves include:

• Failing to update the curves frequently: S curves must be updated frequently in order to account for the changes in project performance. Failure to update them can result in outdated information and suboptimal decision-making.
• Not leveraging S curves alongside other project management tools: S curves are only one component of the project management toolkit. To maximize their impact, it's essential to leverage them alongside other tools such as Gantt charts and earned value management.
• Failing to communicate the information correctly: S curves will only be effective if all members of the project team can interpret them. Failure to communicate the information correctly can result in misinterpretation and confusion.
• Focusing exclusively on the cost curve: The cost curve is indeed a vital measurement, however, it is not an exclusive one. Focusing exclusively on the cost curve can result in the neglect of other critical factors such as schedule and resource allocation.

By avoiding all of the above pitfalls, you can make S curves an effective and powerful mechanism for managing your construction project.

Final Thoughts

S curves are a very valuable construction project management tool. With them, you are able to monitor project performance, ascertain how the project is performing against the planned schedule and also against the planned finances, and make decision-making based on facts to ensure project success. However, for you to maximize the use of S curves, it is critical to leverage them alongside other project management tools and techniques and avoid pitfalls such as a lack of updating the curves from time to time or an over-reliance only on the cost curve.

When used appropriately, S curves can assist construction project managers in keeping the project on course, handling the expenditure, and maximising the allocation of resources. They are an indispensable management tool for making sure that your project is delivered on schedule, to a reasonable cost, and to the required standards of quality. Follow the advice and best practices set out in this article, and you will be well down the road to becoming a S curves expert and a successful construction project manager.

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