Basic Steps for Scheduling

1- Define the time unit

2- Estimate activity required  time

3- Complete project duration

4- Establish activities early & late start and finish dates

5- Identify critical activities

6- If required, shorten project duration

7- Minimize resource demand conflicts

8- Make a calendar dates schedule

TIME ESTIMATING STEPS:

A. Select time interval to be used:

* Governed by practice, time needed to perform acts

* Commonly working day: 8hr/day

* For large projects –  6days/week

B. Estimate each activity time duration based upon methods to be used and resources to be applied.

ESTIMATING RULES:

1- Subdivide activity if it helps to reduce duration uncertainty.

2- Consider only one activity at a time (independent)

3- Assume a normal level of resources

4- Assume a normal work day and work week

5- Don’t consider known calendar completion dates

6- Use consistent time units

ESTIMATING METHODS:

1- Work involves labor or equipment: a. Establish duration based on (i) Production rates (ii) Labor unit costs; b.Efficiency improvement for repetitive activities must be considered.

2- Operations that do not appear in usual cost estimate but consumes time: a. Concrete curing, obtaining permit b. Duration based on experience and judgement

3- Work done by other agency: a. Subcontractors, material suppliers, the Owner b. Subcontractors and material suppliers should supply estimates for their own operations.

4- Uncertainty: a. A simple probability technique can be used to estimate activity duration: (A) Optimistic time (min) (B) Pessimistic time (max.)  m: most likely time (normal):   (A+4M+B)/6

5- Time Contingency: No allowance should be made in time estimate for contingencies, such as flood, rain, fire, accidents, strikes,etc.

6- Total Float: a. Activity with zero TF have no spare time and is therefore one of the activities that controls the project durations, b. Activities with zero TF are called critical activities.

7- Critical Path: It is the longest path which determines the lenght of time necessary to complete all activities.

Hakkında Cumhur Şamiloğlu
Civil Eng., MRICS Management of International Business (MSc-2002)

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