Project Management: Critical Path, Iron Triangle, and Project Types

This article covers critical path, iron triangle, and different project types like derivative, platform, breakthrough, and blue sky project in project management. It also discusses the ways in which a project manager may choose to compromise some dimensions of the iron triangle, depending on the nature of a particular project. The subject is project management and the content is suitable for students pursuing courses in project management. The college/university is not mentioned.

Project Management
Table of Contents
Question 1:.......................................................................................................................................1
a) Find the critical path, duration and cost for this project.....................................................1
b) If each task requires one decorator then, assuming that all tasks are to take place at their
earliest start times, how many decorators are required for the project?.................................1
c) Is it possible to reallocate activity start and finish times so as to reduce the number of
decorators required: i) Without making the project any longer?............................................2
ii) Without increasing the length of the project by more than five days? In each case, carefully
explain and show why, or why not and state any possible disadvantages of the changes
suggested................................................................................................................................2
Question 2:.......................................................................................................................................2
a) If all activities were to take place at their normal durations, find the project duration,
identify the critical path(s) and calculate the given total project costs...................................2

b) Crash the project to a minimum duration at the lowest possible cost. Explain why your
solution represents a minimum time solution and find the total cost at minimum time........3
Question 3:.......................................................................................................................................5
What is meant by the ‘iron triangle’ in project management? Discuss the ways in which a
project manager may choose to compromise some dimensions of this triangle, depending on
the nature of a particular project. Give different examples to illustrate your answer............5
Question 4:.......................................................................................................................................7

Question 1:
a) Find the critical path, duration and cost for this project
A 5 G 5
0 5 9 14
0 5 9 14
B 3 E 4 F 7 J 3
0 3 5 9 5 12 5 8
2 5 5 9 4 11 11 14
C 2
0 2
2 4 H 3
5 8
D 3 11 14
0 3
4 7
I 4
3 7
7 14
The critical path is AEFJ, with the time duration of 19 days.
Cost: sum of normal costs + 19* 400= £20000 + £7600 = £27,600
b) If each task requires one decorator then, assuming that all tasks are to take place at their
earliest start times, how many decorators are required for the project?
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c) Is it possible to reallocate activity start and finish times so as to reduce the number of
decorators required: i) Without making the project any longer?
ii) Without increasing the length of the project by more than five days? In each case, carefully
explain and show why, or why not and state any possible disadvantages of the changes
suggested.
Question 2:
a) If all activities were to take place at their normal durations, find the project duration, identify
the critical path(s) and calculate the given total project costs.
A 5 C 6
0 5 5 11
3 8 4 10
E 2 F 3
8 10 10 13
8 10 10 13
B 8 D 3
0 8 11 13
0 8 10 13
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The critical path is ACD, with the time duration of 14 days.
Cost: sum of normal costs + 14* 120= £2000 + £1680 = £3680
b) Crash the project to a minimum duration at the lowest possible cost. Explain why your
solution represents a minimum time solution and find the total cost at minimum time
There are four paths through this project: ACD, AEF, BEF, BD
(this symbol”*” denotes critical path)
A5C6D3 = 14* Option A=50 C=60 D=70
A5E2F3 = 10 for minimum cost, crash A by 1 day (to minimum)
B8E2F3 = 13
B8D3 = 11 Cost= 50
A4mC6D3 = 13* Option C= 60 D= 70 and B=80 E= 20 F= 40
A4mE2F3 = 9 for minimum cost, Crash C and E by 1 days (E to minimum)
B8E2F3 = 13*
B8D3 = 11 Cost= 80
A4mC5 D3 = 12* Options: C= 60 D= 70 and B=80 F=40 and
A4mE1mF3 = 8 Crash C and F by 2 days each (to minimum F)
B8E1mF3 = 12*
B8D3 = 11 Cost=100 per day
A4mC2D3 = 9 Options: B= 80 D= 70
A4mE1m F1m = 6 Crash D by 1 day (D to minimum)
B8E1mF1m = 10
B8D3 = 11* Cost= 70 each day
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A4mC3 D1m = 8 Options: B=80
A4mE1m F1m = 6 Crash B by 4 days to minimum
B8 E1mF1m = 10*
B8 D2m = 10* Cost= 80 per day
A4mC3D1m = 8 * Options: C=60
A4mE1m F1m = 6 Crash by 2 day to minimum
B4m E1mF1m = 6
B4m D2m = 6 Cost= 60 per day
A4mC1m D1m = 6 * Critical and all minimum
A4mE1m F1m = 6* critical and all minimum
B4m E1mF1m = 6*
B4m D2m = 6*
Hence, minimum duration is 6 days as ACD is critical path and the other entire task is at
minimum duration.
Summary Crash Cost Benefit Total Cost
14 £3680
13 A 50 120 £3510
12 C,E 80 120 £3480
11 C,F 100 120 £3460 minimum
10 D 70 120 £3490
8 B 80 120 £3480
6 C 60 120 £3500
So, minimum duration is 6 days with total cost £3500.
c) The minimum durations is 6 days but the minimum cost is £3460 lesser than original cost.
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Question 3:
What is meant by the ‘iron triangle’ in project management? Discuss the ways in which a project
manager may choose to compromise some dimensions of this triangle, depending on the
nature of a particular project. Give different examples to illustrate your answer.
Iron Triangle is represented in the graphical form in the project management to show
how the different projects have certain constraints. The three constraints of the Iron Triangle are
cost, time and scope. The focus of this Iron Triangle in the project management is that for a
project to be successful all the three constraints are required to be balanced. For every industry in
the business organisation the concept remain same the only thing that might differ are the
constraints on the basis of the industry type.
According to the (Kate Eby, 2017), The rule of the Iron Triangle states that if any one constraint
is disturbed or changed than other two are required to be adjusted else quality of the project
suffers. The three constraints are also useful in measuring the success and failure of the project.
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Illustratio
n 1: The Triple Constraint: The Project Management Triangle
of Scope, Time, and Cost, 2021
(Source:The Triple Constraint: The Project Management
Triangle of Scope, Time, and Cost, 2021)

The three constraints are:
Time: the time to complete the project is calculated through its planning phase. The time is
estimated on the basis of complexity of the project, availability of resources, dependency,
barriers etc.
Cost: the cost is sum of all the resources used to complete or deliver the project. It is allocated
budget for the project completion.
Scope: The scope is the amount of work done in delivering the project. Basically it is measure of
planned work implementation.
The project manger plays the main role with the Iron Triangle concept as they are required to
balance the act of above discussed three constraints for the overall project delivery. For instance,
there is the project of new product development and commercialization. In this typical project
the different stakeholders of the company will have different priorities for example the marketing
team will be more interested with quality, financial team with budget and cost, support team for
the stability and reliability of product and senior management for the schedule of the project. All
such factors become tough for the success of the project and their the project manger has to find
out the ways to compromise the constraints of the Iron triangle and adjust other accordingly to
maintain the success and quality.
For example if the support team or marketing group changes the scope of the particular project
and ask to complete the project within same time and cost it will break the cycle of Iron Triangle
and lead to failure of project. In such case the project manager can has way to compromise some
dimension of triangle such as:
 The project manager can skip the testing of product this will consume less resources and
also save the time. Therefore by making such adjustments the Triangle can be balanced
and project can become successful.
For example if the senior manager ask to complete the project in less time the schedule/time
constraint is compromised which means the project needs a way to modify other two constraints
accordingly:
 The project manager can use the 3rd party solution as a way that can cut the development
time and only their will increase in cost and scope is changed by adding new features by
the 3rd party.
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Hence, the Project manager must understand the stretch ability of the Iron Triangle that if any
one constraint is modified and other also has chance of modification because by this quality of
product won't be compromised and successful project can be delivered.
Question 4:
In the project management area there are different types of projects some of the basic
types are derivative, platform, breakthrough and blue sky project. The discussion of these
projects are discussed below:
Derivative project
The derivative projects are just the variations or augmentation in the existing product. This can
also be refereed as the project to lower the price over the time. Basically it is the improvement
project for the product or process or both. In this manager face the difficulty to maintain the
original essence of the product and also has concern that addition might not increase the
additional cost. The example are : change in the car colour, iPod hard drive means the some car
companies bring new scheme of colours.
Platform project
These are the development project type where the company develop new products for the next
generation. This is done by adding some relevant technology or features to the existing product
for the future growth. These type of projects holds the advantage of cost, quality and
performance improvement. The examples of this type of project are Microprocessors of the
computer generations where the new processors are developed with growing technology with the
change in speed, size, cost and storage capabilities.
Breakthrough project
The breakthrough project is the initiative of the group to attain the quantifiable goals and aims at
the best thinking to challenge the prevailing market opportunities with business mindset. For
such project the company's project manager has to divert it from regular mainstream actions and
stretch the thinking to innovate. The project Breakthrough has a stimulated focus for
transformative insight. The main aim of this project type is to evolve the current business and
lead towards sustainable development. The example of such project is hybrid cars or fibre optic
both has evolved the system of data transferring and the cars that doesn't depend on fuels
respectively.
The difficulties associated with this project type to the managers are:
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 The project manager has to take suitable risk for disturbing the mainstream course of
business actions for evolving the business.
 Project manager also face a difficulty of compromising the scope of business and may
also face on budget difficulties.
Blue Sky project
This project means the research level project type where the project has no limits rather posses
the exciting possibilities to conduct the project. In this type of project the project manger
converts or translates the practice or research into the theory. In The blue sky project the
managers draw real experience for the delivery of the project. Blue sky project type are for those
managers who are who have a capabilities to change themselves for better and in order to
achieve more. The most important thing about managing this type of the project is time, results,
money and resources. Example of this type of projects is 3D televisions where the company
requires extensive research to generate something like this for consumers.
The difficulties associated with this project type to the managers are:
 With this type of project the manager also requires the resources for change also the
project requires deep insight of money and time.
 For this project the project manager requires stable business with good financial
performance to develop something new through such project type.
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