Assessment 5 - Hard Constraints
The DCMA sets the use of Hard Constraints to a maximum of 5% of incomplete activities
There are eight types of constraint used in programming which affect the way the programme calculates the timing and duration of activities through the network of logic. However, there will be occasions when a different type of constraint will be needed.
Of these eight types of constraint, the first four are advisory and known as soft constraints:
Soft Constraints are used to guide the programme around an issue, whilst still allowing following task dates & durations to be driven by the logic of the network, subject to compliance with a set restriction, - the soft constraint. They do not impede the calculation of task dates occurring later in the programme.
The default constraint used in programming is ‘As Soon As Possible’ and does exactly what it says, it tells the programme that a task should start at the earliest opportunity as dictated by the logical network of dependencies and durations within the project.
The last four are mandatory controls which allow no leeway on start or finish date and prevent the programme from pushing the constrained date out later. These are known as Hard Constraints:
This type of constraint represents a major risk to the calculation of critical path, as they prevent a task from starting or finishing on a date later that that set. This could obscure and hide an otherwise clear indication of a possible late and costly finish date until it is too late to take corrective action.
Therefore, if a constraint must be used the use of a Soft Constraint is preferable. Ideally, don’t use Hard Constraints at-all in the programme. It’s better to use a deadline on a task needing a fixed date, as this allows the programme to forecast late finish long before the event and allow the opportunity to take corrective action.
