Construction Planning, Scheduling, and Controls
This domain tests planning and control tools: work breakdown, critical path method, float, resource management, schedule updates, and earned value progress measurement.
CPM mechanics
Break the job into a work breakdown structure, then into activities with durations and logical ties (finish-to-start, start-to-start, finish-to-finish) including lags. The forward pass gives earliest start and finish; the backward pass gives latest start and finish. Total float = LS − ES; free float is the time an activity can slip without delaying its successor. The critical path is the longest path through the network (zero total float) and sets the project duration.
Managing the schedule
Resource leveling smooths peaks and can extend duration; crashing adds cost to shorten duration and should target critical activities; fast-tracking overlaps activities and raises risk. Look-ahead schedules drive weekly work; the baseline is only changed by approved change orders.
Earned value
Planned value (PV), earned value (EV), actual cost (AC). SPI = EV ÷ PV (below 1 = behind schedule); CPI = EV ÷ AC (below 1 = over budget).
Worked example
Activity A lasts 4 days. B (6 days) and C (3 days) both follow A. D (2 days) follows both. Path A-B-D = 12 days; A-C-D = 9 days. The critical path is A-B-D, so the project is 12 days. Activity C has 12 − 9 = 3 days of total float, so a 2-day slip in C does not move the completion date. Crashing C would cost money and buy nothing; crashing B, or A, could shorten the job.
Traps that cost marks
- Confusing free float with total float.
- Crashing a non-critical activity and expecting the end date to move.
- Treating percent of cost spent as percent of work complete.
- Failing to update the schedule for approved changes and actual progress.
- Ignoring lags and long-lead procurement activities.