What are the characteristics of large-scale projects that focus managerial efforts on the detailed scheduling of activities.

What are the characteristics of large-scale projects that focus managerial efforts on the detailed scheduling of activities and on project completion dates ?

Project management deals with time- scheduling and resource allocation for these
activities. If the activity times are deterministic then critical path Method can be used as a
systematic method to compute early state and late start times of activities and to identify
critical activitiesTThe slacks associated with each activity can be used for better control
of the project. When activity times are probabilistic, PERT is an effective tool. In this
method three time estimate are made for each activity and these are used to compute
expected project completion time and its variance A project cost-time relationship can be
obtained using project crashing. This can also be used to obtain the optimal project
duration. Resource allocation is one of the major problems in project management. A
simple heuristic is suggested to handle this problem. Now we will study each process in
detail.
Critical path Method (CPM) is an effective tool for project planning and control when
activity times are known with certainty. However, in certain projects like Research and
Development Projects, it seems realistic unrealistic to assume that we can know with
certainty the time durations in which the activities can be completed. In such cases PERT
can be used.
Time Estimates in PERT
In PERT for each activity, three time estimates are made. These estimates are :
a) Most likely Time(TM): the time, which is taken most frequently by the activity.
b) OptiSmistic Time (TO): The time by which activity can be completed, if everything went well.
c) Pessimistic Time (TP): the time by which the activity will get completed even under adverse conditions.



Time the Project Completion
Unlike CPM, in the case when there is uncertainty in activity times, it is not possible to compute the time of completion of the project with certainty. Instead, we shall estimate the expected time and variance of the project completion time. The expected project completion time E (t), can be computed as the length of critical path in the CPM, when activity times are replaced by the expected times (TE) of the activities.
Time cost Relationship And Project Crashing
In addition to time- management, cost plays an important role in any project. The projects costs can be classified in two groups: direct activity costs and indirect project costs. Direct activity costs are those components of the cost, which can be directly linked with the activity, thus direct labour, material consumed , rental charges for the equipment etc. will form part of these costs. For example, by asking the labour to work with OT or with effiency bonus for faster work etc. Crash time is the minimum possible time in which the activity can be completed and the costs associated with this time is the crash cost. Normal cost is the cost incurred when activity is completed in its normal time (or the time used activity time in the critical path computations).
On the other hand, indirect costs are the overheads associated with the entire project including loss of revenue/ benefits due to late completion of the project. This cost will decrease directly with the decrease in the project. Completion time. An optimal project completion time will be the time for which sum of these two costs is minimum. To obtain the optimal time, we have to compute direct activities cost when project duration is reduced by one unit time each time. This is called project crashing.
We summarise the method-4br reducing project completion time as follows:
Stepl: compute for each activity
Cost of reducing activity time by one unit time.
= Crash cost - Normal cost
Normal time — Crash time
Step 2: Identify all the critical paths. Select one activity on each critical path such that the total cost of crashing all these activities by one unit time is minimum among all such that their current activity time is higher than the crash time, i.e. no activity reduction in activity duration can make place beyond its crash time. If there is at least one critical path, on which none of the activities can be crashed, then no further reduction in the project completion time can take place. In that case stop.
Step 3: reduce the activity time for the activities selected for crashing by unit time period and recomputed the early start time, late start Time critical path for the network
Resource Allocation
The analysis up to this point has been based on the assumption that if its predecessors were completed, an activity could begin. Underlying this assumption is the fact that sufficient resources will be available to start activities simultaneously. However, in actual

practice some of the resources may be available in limited quantities. Examples of such resources are expensive equipment, skilled manpower, finances etc. A simple heuristic rule will be as follows:
Stepl; Allocate resources seriously in time. That is start on the first time period and schedules all activities possible with the resources available, then do the same for the second time period and so on.
Step2: When several activities compete for the same resources, give preference to the activities with the least slack. Recomputed the slacks in all the activities.
Step 3: reschedule non-critical activities, if possible, to free resources for scheduling critical or non-slack activities.
Project Updating And Monitoring
For effective use of the above techniques it is essential that project progress should be continuously monitored .As and when there is a change in time schedule of any activity, the project network should be updated and new time schedule finalized. Now days with most of the computers, including PCs, well written CPM/ PERT packages including project crashing and resource allocation are available. These packages will provide all the necessary information needed for efficient project management.