Schedule and Cost Planning
Domain 3 tests schedule and cost planning for security projects: dependency logic, critical path and float, estimating and reserves, and life-cycle cost. Expect calculation items, not just definitions.
Schedule rules
- Define activities from WBS work packages, sequence with dependencies (finish-to-start is most common), estimate durations with the people doing the work, then build the network.
- The critical path is the longest path through the network and sets project duration; critical activities have zero total float.
- Total float = late start minus early start. Free float = how long an activity can slip without delaying the next activity.
- Resource leveling may change dates and extend the critical path; resource smoothing consumes float without extending duration.
- Long-lead procurement (cameras, controllers, head-end servers) frequently drives the schedule more than installation labor does.
Cost rules
- The cost baseline is the approved, time-phased budget excluding management reserve. Contingency covers identified risks from the risk register and sits inside the baseline; management reserve covers unknown unknowns and sits above it, released only with sponsor authority.
- Estimate accuracy ranges: rough order of magnitude roughly −25%/+75%, budgetary about −15%/+25%, definitive about −5%/+10%.
- Life-cycle cost includes installation, licensing or subscription, maintenance, energy, training, and decommissioning - not just the capital purchase.
Worked example
Activity A takes 4 days; B (6 days) and C (3 days) both follow A; D (2 days) follows both B and C. Paths: A-B-D = 12 days, A-C-D = 9 days. The critical path is A-B-D at 12 days. C has 3 days total float, so a two-day slip in C does not move the finish date; a one-day slip in B makes duration 13 days unless B is crashed or the dependency is re-sequenced. Cost side: a $480k baseline with 10% contingency is $528k. A risk never entered in the register cannot draw on contingency - that requires management reserve and sponsor approval.
Traps
- Confusing total float with free float when deciding which slips to escalate.
- Spending contingency on scope changes; contingency is for risks, scope changes go through change control and rebaselining.
- Padding every duration and then adding risk contingency - double counting.
- Scheduling acceptance testing and training after the go-live date.