S CURVE REPORTING FOR COST ENGINEERS AND CONSTRUCTION PROJECT MANAGERS

S-curves, a picture is worth a thousand

words.

INTRODUCTION

what the mysterious S Curve is, why it is an important project

management tool, and how to generate one.

WHAT IS AN S CURVE ?

"a display of cumulative costs, labour hours or other quantities plotted against time.

The name derives from the S-like shape of the curve, flatter at the beginning & end,

and steeper in the middle, which is typical of most projects. The beginning represents

a slow, deliberate but accelerating start, while the end represents a deceleration as

the work runs out."

TYPES OF S CURVE ?

There are a variety of S Curves that are applicable to project management

applications, including...

 Man Hours versus Time S Curve

 Cost versus Time S Curve

 Baseline S Curve

 Actual S Curve

MAN HOURS VERSUS TIME S CURVE

The Man Hours versus Time S Curve is appropriate for projects that are labour

intensive. It shows cumulative man hours expended over time for the duration of

the project. As man hours are a product of man power and working hours, these

may be adjusted individually or together to ensure the project remains on schedule

COST VERSUS TIME S CURVE

The Cost versus Time S Curve is appropriate for projects that contain labour and

non-labour (e.g. material supply / hire) tasks. It shows cumulative costs expended

over time for the duration of the project, and may be used to assist in the

calculation of the project's cashflow.

BASELINE S CURVE

Prior to project commencement, a schedule is prepared outlining the proposed

allocation of resources and the timing of tasks necessary to complete the project

within a set time frame and budget. This original schedule is referred to as the

Baseline Schedule. From this schedule, a Baseline S Curve is generated. This S

Curve reflects the planned progress of the project.

TARGET S CURVE

ACTUAL S CURVE

The production schedule is updated on a regular basis throughout the duration

of the project. These updates include the revision of percentage complete for

each task to date. Using this information, an Actual S Curve may be generated.

This S Curve reflects the actual progress of the project to date, and may be

compared with the Baseline S Curve to determine how the project is

progressing.

VALUE AND PERCENTAGE S CURVES

S Curves are useful for calculating the project's actual percentage complete

against baseline percentage complete, and for calculating the project's

percentage growth (or shrinkage).

WHY USE A S CURVE?

 an important project management tool.

 allow the progress of a project to be tracked visually over time,

 form a historical record of what has happened to date.

 allow project managers to quickly identify

o project growth

o slippage

o potential problems

that could adversely impact the project if no remedial action is taken.

DETERMINING PROGRESS

Comparison of the Baseline S Curve and Actual S Curve reveals the progress of

the project over time. In most cases, the Actual S Curve will sit below the

Baseline S Curve for the majority of the project (due to many factors). Only

towards the end of the project will the curves converge and finally meet. If the

project is ahead of schedule, the Actual S Curve will rise above the Baseline S

Curve.

PROJECT BENCHMARKS

HOW IS A S CURVE GENERATED ?

In order to generate a S Curve , a Baseline and Production Schedule are required.

These schedules should contain the following information for each task...

 Baseline / Actual Start Date, Finish Date

 Baseline / Actual Man Hours, Costs

 Actual Percentage Complete

SUMMARY

 S Curves may be used by Project Managers to track the progress of their Projects.

 Graphical tracking allows the quick and timely identification of potential problems

that could adversely affect the progress of the Project.

 S Curves may also be included in the routine Progress Reports required by Senior

Management