7. implementation (1) time management

Project Management –
Implementation (1)
8/13/2017 1Arch. Dania Abdel-Aziz/ Lecture 7
University of Jordan
Year 2016/2017
First Semester
Arch. Dania Abdel-Aziz

We are going to discus Project management under those main three
headlines:
1. Description.
2. Application.
3. Implementation Procedure.
8/13/2017 Arch. Dania Abdel-Aziz/ Lecture 7 2

3. IMPLEMENTATION

3. PROJECT SCHEDULING

Determining sequence of work:
• Once the activities have been identified the next stage is to sequence
them according to their dependencies. In other words, any relationships
between activities need to be identified so that dependent activities can
be scheduled to follow those that they are dependent upon

• Building network / interdependence

• Analysis of interdependence
It is important to classify any dependencies properly because they indicate
the sequence in which activities must occur. There are four types of
dependency relationships. As mentioned in earlier lectures.

Types of Dependencies
Three types of dependencies are used to define the sequence among the
activities:
1. Mandatory Dependency (hard Logic).
2. Discretionary Dependency (Soft Logic).
3. External Dependency.

• Estimation of total duration (CPM, PERT)
A complex project would normally encounter several delays and may surpass
the budget allocated for it making a project very costly and which may
lead to losses.
To get over those problems we use techniques such as:
1)The Critical Path Method (CPM)
2)Program Evaluation and Review Technique (PERT)

Critical Path Method (CPM)
• A technique that is used in projects that have predictable activities and
tasks such as in construction projects.
• It allows project planners to decide which aspect of the project to reduce
or increase when a adjustment is needed.

• Estimation of total duration (CPM, PERT)
Critical Path Method (CPM)
• Assume that you have been giving this Network Diagram for a general
construction project:
Project Stage Activity Immediate
Predecessors
Time (Months)
Foundation A 4 Months
External Site
Works
B A 8 Months
Building
Skeleton
C B 8 Months
Utilities D B 2 Months
Finishing E C, D 4 Months

1. Draw Network Diagram

RULES WHEN USING THE FORWARD PASS
• Add all activity times along each path as we move through the network
(ES + Dur = EF),
• Carry the EF time to the activity nodes immediately succeeding the
recently completed node. That EF becomes the ES of the next node,
unless the succeeding node is a merge point.
• At a merge point, the largest preceding EF becomes the ES for that node.

We Pick the larger earliest finish.

RULES FOR USING THE BACKWARD PASS
• Subtract activity times along each path as you move through the network
(LF – Dur = LS),
• Carry back the LS time to the activity nodes immediately preceding the
successor node. That LS becomes the LF of the next node, unless the
preceding node is a burst point.
• In the case of a burst point, the smallest succeeding LS becomes the LF for
that node.

When Total Float is 0, means
there is no flexibility at all
Total Float= (ES-EF) or (EF – LF)

The Critical Path is:

Exercise:
Considering the information, answer
the following questions:
• What is the critical path?
• Determine the project duration?

Solution

• In this network diagram, the activities are represented by an arrow and
connected by nodes.
• The nodes represent an event which could be the start or completion of
an activity.
• Finish-to-start is the only relationship that can be used to express the
dependency between activities when using the AOA approach.
• Sometimes it is necessary to use a dummy activity, which is an activity that
has no time, to maintain the logical relationships in an AOA network
Activity on Arrow (AoA)

Activity on Arrow (AoA)
Activity name
Earliest finish
Latest finish Duration

Estimating the Time Required
• This step involves estimating the amount of effort required for each activity and
then calculating the total duration. Effort is the work to be done whereas duration
is this figure divided by estimated resources.
• For example, If there is a requirement to build one hundred meters of wall and a
bricklayer can build 5 meters of wall in a day. The duration of the task can be
calculated by dividing the length of the wall by the number of bricklayers that will
be assigned to the task. Then five bricklayers could be expected to complete the
task in 4 days.

PERT: Program Evaluation and Review Technique
PERT is used in projects that have unpredictable tasks and activities such as
in research and development projects.
• It utilizes three estimates of the time to complete the project:
1. The most probable (m).
2. The optimistic (O).
3. The pessimistic (p).

Difference between CPM and PERT

Calculating time using Pert Method
PO

Exercise
• What is the time estimate of the following activity in which the optimistic
estimate is 4 days, pessimistic is 12 days, and most likely is 5 days? Show
your work.

Using the Beta distribution for probabilistic estimation, the formula is given as:
ED = (o + 4m + p)/6
Where:
ED = Estimated time for activity
o = most optimistic time to complete the activity
m = most likely time to complete the activity, the mode of the distribution
p = most pessimistic time to complete the activity
The solution to this problem is:
ED = (4 + 4(5) + 12)/6, or
= 6
Solution

Consider the following project tasks and their identified best, likely, and worst case
estimates of task duration. Assume the organization you work for computes ED
based on the standard formula. Calculate the ED for each of the following tasks
(round to the nearest integer):
Exercise

Solution
Using the Beta
distribution for
probabilistic
estimation, the
formula is given as:
ED = (o + 4m + p)/6

Exercise 2
• http://optlab-server.sce.carleton.ca/POAnimations2007/PERT.html

• Determination of Critical Path.
• Graph on time chart (Gantt chart).
• Determining human resource loading.
• Establishing milestones / reporting periods.

STEPS TO REDUCE THE CRITICAL PATH
1. ELIMINATE TASKS ON THE CRITICAL PATH.
2. REPLAN SERIAL PATHS TO BE PARALLEL.
3. OVERLAP SEQUENTIAL TASKS.
4. SHORTEN THE DURATION ON CRITICAL PATH ACTIVITIES.
5. SHORTEN EARLY TASKS.
6. SHORTEN LONGEST TASKS.
7. SHORTEN EASIEST TASKS.
8. SHORTEN TASKS THAT COST THE LEAST TO SPEED UP.

Fast Tracking vs Crashing

Fast Tracking
• Fast tracking is a technique where activities are performed in parallel, although these activities
would have been performed sequentially using the original schedule.
• It is usually important to start with this technique first. The main reason for this is that fast
tracking does not involve any costs. It is simply a rearrangement of the activities in the
original schedule.
• It leads to an increase in the risk, because activities that were originally intended to be
performed sequentially are now performed in parallel. It may lead to a rework or
rearrangement of the project. This reworking of the project can cause loss of even more
time.

Crashing
Crashing is the technique to use when fast tracking has not saved enough time on the schedule.
• It is a technique in which resources are added to the project for the least cost possible.
• Cost and schedule tradeoffs are analyzed to determine how to obtain the greatest amount of
compression for the least incremental cost.
• Crashing is expensive because we are adding more resources to the project. Undoubtedly, if
you add more resources to an activity or project, it is going to cost you more. It only works
for critical path activities where it is possible to shorten schedules.

Crash cost & crash time have a linear relationship:
Crashing

Crash cost & crash time have a linear relationship:
$2000
5
$400 /
Total Crash Cost
Total Crash Time weeks
wk


Crashing

Comparison of these two techniques

Example
• The table below shows the normal times and costs, the crash times and
costs for an house building project.
• Calculate the per week costs for crashing for each activity
• Which are the most attractive candidates for crashing? Why?

2000
1500
3000
600
21000
600
7000

• The network and durations given below shows the normal schedule for a project.
You can decrease (crash) the durations at an additional expense. The Table given
below summarizes the time-cost information for the activities. The owner wants
you to you to finish the project in 110 days. Find the minimum possible cost for the
project if you want to finish it on 110 days.
Crashing Example:

• Quiz

References
• Text book for this course
• Jeffrey K. Pinto, INSTRUCTOR’S RESOURCE MANUAL, CHAPTER NINE,
Project Scheduling: Networks, Duration Estimation, and Critical Path
• http://www.free-management-ebooks.com/faqpm/schedule-03.htm
• http://constructionengineeringandmanagement.blogspot.com/2011/11/p
roject-schedule-network-diagram.html
• http://www.simplilearn.com/fast-tracking-vs-crashing-article

Thank you 

7. implementation (1) time management

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