The Critical Path Method (CPM) - Construction Project Scheduling and Control - page 64

Critical activity: An activity on the critical path. Any delay in the timely comple-
tion of a critical activity will result in a delay in the entire project.
Critical path: The longest continuous path in a network from start to finish. It
represents the summation of the durations of activities and lags along that path,
taking into consideration calendars, constraints, resources, and other impacting
factors.
Driving relationship: A relationship from a predecessor activity that controls the
start or finish of a successor activity. For any activity with predecessors, there must
be at least one driving relationship.
Early dates: The early start date and early finish date of an activity.
Early finish (EF): The earliest date on which an activity can finish within project
constraints.
Early start (ES): The earliest date on which an activity can start within project
constraints.
Event: A point in time marking the start or end of an activity. In contrast to
an activity, an event does not consume time or resources. In computer software,
events with significance can be created as milestones, and they are either start
milestones ,suchasNoticetoProceed,or finish milestones , such as Substantial
Completion.
Forward pass: The process of navigating through a network from start to end
and calculating the completion date for the project and the early dates for each
activity.
Late dates: The late start date and late finish date of an activity.
Late finish (LF): The latest date on which an activity can finish without extending
the project's duration.
Late start (LS): The latest date on which an activity can start without extending
the project's duration.
Total float (TF) : The maximum amount of time an activity can be delayed
from its early start without delaying the entire project or violating a schedule
constraint.
Tip Box 4.10
A project manager needs to decide on a single set of dates within the range of early/
late dates. Never give your subordinates two start dates and two finish dates.