Construction Management and Project Planning
Core concepts
Understand project delivery methods (design-bid-build, design-build, CM-at-risk), the critical path method (CPM), float (total and free), resource leveling, earned value management (PV, EV, AC, CPI, SPI), and cost and schedule control. Know contract types (lump sum, unit price, cost-plus) and their risk allocation.
Common traps
- Total vs. free float: total float is the slack before project completion is delayed; free float is the slack before the next activity is delayed.
- Critical path: the longest path, not necessarily the path with the most activities. Multiple critical paths can exist.
- Earned value: CPI = EV/AC, SPI = EV/PV. CPI below 1 means over budget; SPI below 1 means behind schedule.
- Contract type risk: lump sum shifts risk to the contractor; cost-plus shifts risk to the owner.
Worked rule of thumb
When computing float, forward-pass to get early starts and finishes, backward-pass to get late starts and finishes. Total float = LS − ES = LF − EF. The critical path has zero total float. For earned value, a quick diagnostic: CPI < 1 and SPI < 1 means the project is over budget and behind schedule simultaneously - a common exam scenario.
Resource leveling may extend the schedule (consuming float), while resource smoothing works within existing float.