What is S Curve in Construction Planning?

It is demarcated as curve of cumulative project cost planned against time, which usually follows the shape of the letter "S": The beginning of curve represents a slow, but accelerating start, while the end of curve represents a deceleration as the project comes to an end. The S curve could be considered as an indicator of key dates achieved in project, baseline vs actual progress, cost, time etc.

At first phase there are less opportunities for spending money as the project is in its earlier stage and less activities, when the time passes by, more and more activities are started in the project which require more resources and thus the cost increases sharply with time. In the third phase when the project is about to complete and the activities are finishing up (many activities are already completed) so the increase in cost becomes less likely and graph moves until it becomes constant.

In order to be able to generate an S Curve, a Baseline (contain information about Actual Start date and finish date, labors, hours and costs) and Production Schedule (contains information about the actual percentage complete) are required.

Usages of S curve in Construction Planning

1. Used for performance tracking
2. ‘S’ Curves are an important project management tool. They allow the progress of a project to be tracked visually over time
3. A historical record of what has happened to date
4. Analysis of S Curves allow project managers to quickly identify project growth, slippage, and potential problems

Reference: http://www.aboutcivil.org/