TASK dependencies show the relationships or dependencies between tasks and are used to establish the sequencing needed to accomplish the work.

Finish – to – Start

AB – An earlier activity, the predecessor (A) is completed and the next one, the successor (B) is begun. Sometimes, the succeeding activity is not started immediately and there is a lapse of time between the end of the predecessor and the start of the successor. The lapse time is called the lag.

Finish – to – Finish

AB – The two activities are completed almost at the same time. One task may finish before the other, yet each must be completed before the commencement of the successor.

Start – to – Start

AB – The activities are started at the same time. One activity may start later than the others. The gap between the start of one activity and the start of the other activity is called the lag.

Start – to – Finish

AB – In start to finish, activity A is started, before activity B is completed.

Critical Path Analysis

The critical path in the network diagram is the sequence of activities with the longest duration to complete the project. The critical path typically has no slack. The slack or float is the amount of time that an activity can slip or be delayed without delaying the finish date of the project. Activities on the critical path cannot be delayed. A delay in any of the activities on the critical path will delay the whole project. The slack (float) is the amount of time an activity can be delayed without delaying the project completion.

Critical path analysis helps identify the activities that must be completed on time in order to complete the entire project on time. It shows the tasks which can be delayed and for how long without impacting the overall project schedule.

Reasons for Scheduling

Schedules are used to create the logical sequence of execution of the activities in a project which determine the completion date for the entire project. Most projects have a deadline imposed. The critical path helps to identify the activities that will determine the project end date. It is very easy to create good schedules, especially with modern software. A good schedule on paper will not work if resources are not available to implement it as at when due. Schedules are useless without resources.

Another factor hindering schedule implementation is when there is frequent change to the scope of the work that tends to alter the critical path. Scope creeps are created by inadequate upfront definition and planning. They happen because something was left out. Better project definition and planning in the beginning usually reduces scope creep.

Resource Allocation

Resource allocation is the planning function for organizing both people and things for efficient and effective project performance. Resource planning enables the determination of all the resources required for the project, how much of each and when they are needed for the project. These include the people, materials and equipment. The key information required for the resource planning are the activity list, the resource availability, and the project management plan. The following factors should also be given consideration when assigning the people resources.

Availability
Available budget
Education and training
Skill requirements

The techniques for resource planning include expert judgment and project management software.

If resource planning is poor, the project will suffer schedule slippage for various reasons such as not having enough personnel and not having access to materials and equipment for the execution of the project. Engr. Obumeyan is a Chartered Chemical Engineer and is presently engaged as Consultant on the Abuja Light Rail Project.