Post on 09-Apr-2018
8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Ioannes Tang
Assistant Professor
Department of Civil Engineering
Faculty of Engineering
Room: B1C21, Telephone: 03-8924 8346
Email: Ioannes.Tang@nottingham.edu.my
Originally prepared by
Mick Mawdesley
H24 MPR Lecture 6
Uncertainty in Planning
8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
http://slidepdf.com/reader/full/1011-h24mpr-lecture-6-uncertainty-in-planning 2/15
Uncertainty in Planning
• The construction industry is uncertain
– It builds complex projects in uncertain
conditions
– The weather affects it
– The ground conditions affect it
– It uses materials which have properties that
are uncertain – It uses largely unskilled / low skilled workers
– It has clients who change their minds
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Uncertainty in Planning
• Planning should reduce uncertainty but,
with all this uncertainty:
– How do we decide on durations?
– How do we decide on resources?
– How can we ensure safety?
– How do we make sure that the environment
is not adversely affected?
• Without being able to do these, we
cannot produce good plans.
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Uncertainty in Planning
• We need good records (information)
• We need to carry out sufficient
investigations
• We have to investigate alternatives
• We have to make judgements
• We have to recognise that plans will needto be updated from time to time – control
action is necessary
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Uncertainty in Planning
• These solutions will ‘solve’ most planning
problems and help reduce uncertainty in
construction projects
However:
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Situation 1
• Many tasks in projects have to be
repeated. e.g.
– Pile driving until a particular set is achieved
– Submission of plans for planning permission
– Development of designs until client satisfied
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Question
• How do we determine the duration of
such activities in order to plan the
project?
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Situation 2
• Consider Tingham bypass
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Say that the client has
specified:
We have to build the bypass
with bridges at both High Roadand Low Road
But we can only affect
either High Road or Low Road
at any one time – not both at
the same time.
Question:
How do we draw the network
for the project?
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Possible solution?
Start andPreparation Finish
Const. HighRoad Bridge
ReopenHigh Road
Close HighRoad
Const. LowRoad Bridge
ReopenLow Road
Close LowRoad
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Possible Solution?
• Only if:
– We use resource scheduling (but what
resources?)
– Or we use some similar methods to ensure
constraint is obeyed
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Possible Solution?
Start andPreparation Finish
Const. HighRoad Bridge
ReopenHigh Road
Close HighRoad
Const. LowRoad Bridge
ReopenLow Road
Close LowRoad
Which is correct?Indeed, is either correct?
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Possible Solution?
• We need a ‘Decision Box’
Start andPreparation
Finish
Const. HighRoad Bridge
ReopenHigh Road
Close HighRoad
Const. LowRoad Bridge
ReopenLow Road
Close LowRoad
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8/8/2019 1011 H24MPR Lecture 6 - Uncertainty in Planning
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Possible Solution?
We need a ‘Decision Box’
Start andPreparation
Finish
Const. HighRoad Bridge
ReopenHigh Road
Close HighRoad
Const. LowRoad Bridge
ReopenLow Road
Close LowRoad
Const. HighRoad Bridge
ReopenHigh Road
Close HighRoad
Const. LowRoad Bridge
ReopenLow Road
Close LowRoad
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Possible Solution
• Eisner suggested this in the early 1960s
• How do we do the calculations?
•Very difficult!!
• Is the idea any use?
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