Basic Steps for Scheduling
Nisan 30, 2014 Yorum bırakın
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.
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
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.