Download Weather and Contingency Allowance

Weather and Contingency Allowance
• Two approaches for assignment of weather
allowance:
1. Add the Weather Allowance at the end of
the project as a separate activity.
2. Add Weather Allowance to those affected
by the weather.
* Can add weather allowance at the end of
each construction segment ( site
preparation, foundation…etc. )
* Other contingency items.
-- Procurement Allowance
-- Strikes
Time Zero
The close of the work period immediately
preceding the start of the project.
Scheduling Computations
for Arrow Diagram
Four time values associated with each
activity:
1.ESD
Early start date
2.EFD
Early finish date
3.LSD
Late start date
4.LFD
Late finish date
Early Start Date for an activity is the
earliest point in time that any activity
bursting from its beginning node can start.
Late Finish Date is the latest point in time
that any activity which merges at the
activity’s ending node can finish.
Types of Activities
1. Production Activities
Those that can be taken directly from plans
and specifications
2. Procurement Activities
Procurement of material and equipment
3. Management Decision Activities
Activities that can be created by
management to avoid certain situations
- Delay Concrete
- Company Vacation
Precedence Diagram
Advantages of Using Precedence Diagram
1. No dummy activity are required
2. A single number can be assigned to
identify each activity.
3. Analytical solution is simpler.
* Numbering System
Same concepts used in Arrow diagram
– Even or odd or in fives or tens
– Smaller numbers to the left
– Each Activity has its unique number.
Constructing the Precedence Diagram
1. Create Activity list and eliminate
redundancies.
2. Construct Rough Diagram “ Ball of
string”
– Activities with no dependencies arranged at the
left.
– Create dummy start if you have more than one
start “ Contract Award”
– Ball-of-string provides a mean to determine
sequence steps for each activity.
Constructing the Precedence Diagram (cont.)
3. Arrange Activities in a sequential order
– Start by first activity “Contract Award”
– Possible sequence step are those activities
located at the arrow head
Estimating Activity Duration
Time Interval
• Time Interval is selected according to the
nature of the activity (seconds - minutes…)
• It is common practice in construction
industry to use calendar day.
• Use one and only one time unit for any
schedule.
Estimating Activity Duration
1. From Company’s Record
2. From Standard Estimating Guide
3. Interviewing Field Personnel.