Leads and Lags in Project Scheduling

Correct Answer: The successor activity must start 5 days after the predecessor starts and finish 10 days after the predecessor finishes

When a schedule has both Start-to-Start (SS) and Finish-to-Finish (FF) relationships between two activities, each relationship functions independently to control different aspects of the activities' timing. The SS+5 relationship means the successor activity must start 5 days after the predecessor starts. The FF+10 relationship means the successor activity must finish 10 days after the predecessor finishes. Both conditions must be satisfied simultaneously, which means the successor activity must start 5 days after the predecessor starts AND finish 10 days after the predecessor finishes. The other answers are incorrect because: - A constant duration offset would require the same lag value for both relationships - Total float is unrelated to the relationship constraints in this scenario - Splitting the activity would not resolve the dual relationship requirements and would unnecessarily complicate the schedule

Correct Answer: Leads reduce duration by allowing parallel work, while lags enforce necessary waiting periods between activities

The correct answer states the fundamental truth about leads and lags in schedule optimization. Here's why: Leads are negative time adjustments that allow activities to start earlier than they normally would, enabling parallel work and schedule compression. For example, starting painting when plastering is 80% complete, rather than waiting for it to finish completely. Lags are positive time adjustments that enforce necessary waiting periods between activities, such as concrete curing time or paint drying time. The other options are incorrect because: - Leads do not require additional resources; they are timing adjustments, not resource modifications - Leads and lags do not need to be equal in duration; they are independent timing adjustments based on specific activity requirements - Leads and lags can apply to any dependency relationship type (FS, SS, FF, SF), not just specific relationship types

Correct Answer: The successor activity can start 3 days after the start of its predecessor

In project scheduling, a Start-to-Start (SS) relationship with a lead value of +3 means the successor activity can begin 3 days after the start of its predecessor. This is the fundamental definition of a positive lead time in an SS relationship. A positive lead value in this context indicates a delay between the start dates of the two activities, while a negative lead value (lag) would indicate the successor starting before the predecessor. The other options are incorrect because: - Starting before the finish of predecessor contradicts the SS relationship definition - Starting after completion of all predecessors describes a Finish-to-Start relationship, not SS - Maintaining a constant buffer throughout duration misinterprets the lead concept, which only affects the start timing