Dependency of Project Activities

Dependency of Project Activities

Project completion within allocated time is critical for business value attached to it and one of the critical criteria for project success (Atkinson, 1999). One project will be completed when all activities or tasks in that project will be completed. These activities could be completed successfully if project team knows that when to start which activity. This information of logical sequence of activities is shown in network diagrams (Ramakrishna, 2010, p. 124) based upon dependency of activities. Activity dependency is relation of one activity with one or more other activities i.e. one activity will start with the start or end of another activity or it will finish with the start or finish of another activity (Schwalbe, 2006, p. 112).

Dependency of all activities and type and nature (constraint) of dependency should be marked clearly and known at all stages of project to keep project at track/schedule and to review project plan if needed (Wysocki 2012). Activities dependencies could be of four types Finish-to-Start (FS), Finish-to-Finish (FF), Start-to-Start (SS) and Start-to-Finish (SF) and this depends upon different factors or constraints. Wysocki (2012) has described these constraints in detail and divide them in four categories of Technical, Management, Inter-project and Date constraints. These constraints are described below in detail with practical examples;

Technical Constraints: According to Wysocki (2012, pp. 206-207) any constraint which comes to act due to some conditions within project is described at technical constraint. This type of constraint could be due to availability of resources, previous experience about similar activities, input requirements from other activities or risk mitigation. This should be noted that PMI (2008) has divided this in two different categories of mandatory and discretionary constraints while Wysocki has expanded these under Technical Constraints to address different issues arise during project. Mandatory constraints applied to any activity are difficult to be changed and sometimes require extra resources while other constraints could be changed during any stage of project according to risk or schedule of project assigned to these activities.

Practical example of this type of constraint normally occur in every project as recently my company is carrying out Hail Public Transport Study for which environmental data collection activity was delayed due to same technician has to work at other activity of traffic data collection. Another example was to delay the work at best possible scenario design till the approval of previous work from Ministry of Transport.

Management Constraints: Wysocki (2012, pp. 207-208) has described this as some external factors changing the sequence of activities. These factors lie outside of task or activities in a project and imposed by the management to ensure risk mitigation or business value of one project. A practical example of this constraint was applied in a project of Traffic Impact Study when Traffic Data Collection activities were delayed due to upcoming vacations and exams of schools. Because data collection activities cannot be completed before school vacations and during school vacations the traffic volumes are not considered as normal and high peak to represent actual rush hours.

Inter-project Constraints: Wysocki (2012, p. 208) has described