Glossary - Construction Project Scheduling and Control - page 483

Network —A graphical representation of the activities (and events) composing the
project, in a logical and chronological depiction. Network diagrams are basically
of two types: arrow networks and node networks . Arrow networks are also called
arrow diagramming method (ADM), activity on arrow (AOA) ,orthe I-J
method . Node networks are also called activity on node (AON) or Node
Diagramming Method. Precedence diagrams or precedence diagramming method
(PDM) are an advanced form of node networks.
Noncompensable Delay —A project delay beyond the control, and not the fault of,
the owner, caused byunusual weather conditions, natural disasters (earthquakes,
floods, hurricanes, etc.), wars or national crises, and labor strikes. Such delays
usually do not entitle the contractor to monetary compensation but most likely
entitles the contractor to a time extension.
Nondriving Relationship —A relationship between a predecessor and a successor
that does not affect the current activity dates. If a nondriving relationship is
omitted, the CPM calculations—including all activity start and finish
dates—should not change. However, a nondriving relationship may become
driving if network conditions change, such as activities' durations or logic, or if
activities are added or deleted.
Nonexcusable Delay —A delay that does not entitle the contractor to either a time
extension or monetary compensation.
Nonworkdays —Days on which no work is/was performed, such as holidays, rain
days, shutdowns, and the like. Nonworkdays are of two types: known, such as
holidays and scheduled shutdowns, and unknown, such as weather days and
unscheduled shutdowns.
Normal Cost —The cost of a project that is performed within the Normal Duration .
Normal Distribution —A probability distribution forming a symmetrical
bell-shaped curve.
Normal Duration —The amount of time it takes to finish the project under
ordinary circumstances without any deliberate acceleration or deceleration.
Optimistic Duration —Optimistic duration is the amount of time an activity is
expected to take if everything goes smoothly and efficiently within the
realistic—even though this may not be likely—realm of expectations.
Original Duration —The number of time units (days, weeks, months, etc.)
estimated to complete an activity that has not started yet.
Overhead —See Indirect Cost .
Overlapping Activities —Two activities are said to overlap when the successor starts
while its predecessor is in progress. Mathematically speaking, the duration of the
combination of the two activities is less than the summation of the two activities'
durations.
Payment Request (Pay Request, Payment Requisition) —A formal written
request for payment by a contractor or subcontractor for work completed on a
contract and—if allowed for in the contract—materials purchased and stored on
the job site or in a warehouse during a specified period of time. Subcontractors