Schedule Risk Management - Construction Project Scheduling and Control - page 374

conditions can push them onto the critical path. This is highly useful and makes the
Monte Carlo simulation a valuable, worthwhile tool.
Specific Risk Events
Specific risk events are potential impacts on the schedule that may or may not occur,
such as accidents and other events that are difficult to predict. Specific risk events
include several types that are analyzed by several methods, but the initial step in pre-
dicting them is to hold a brainstorming session in which the project's team members
identify as many potential risk events as possible and create a risk register or checklist
of those events. The process of identifying potential risk events for a project is valu-
able, because it helps the project management team to start thinking about risk issues
and to produce a more realistic schedule.
Another type of specific risk event includes determining the additional scope of
work activities that may or may not happen, activities that are present in the schedule
but may require unplanned multiple cycles to complete, or activities that have signifi-
cant variability. It is important during brainstorming to review historical records and
experiences in order to determine which of these types of risks may occur during the
project that is under way. These risks probably are dependent on other factors, such
as the personnel involved, the type of project, the time frame, and the budget.
There are several methods that can be used to analyze specific risk events.
Modeling a specific risk by creating a string of activities to represent the scope of
work due to the risk (called a “what-if scenario”) is one good way to attempt to
determine the potential ramifications of the realization of that risk. This is the same
approach that would be taken during a project if a changed condition appeared
to impact the schedule and the project management team needed to assess the
potential ramifications of that change. In this situation, the contractor would prepare
a prospective time impact analysis (TIA). A prospective TIA would be prepared by
using the current updated schedule, inserting a linked group of activities that would
model the changed condition, and recalculating the schedule to see if the finish
date changed. This linked group of activities is called a fragmentary network, or
fragnet . The degree of change to the finish date is an indication of the number of
days that the changed condition would affect the critical path and delay the project.
An excellent description of a prospective TIA is provided by the AACE International
in their Recommended Practice No. 52R-06, “Time Impact Analysis—As Applied in
Construction.” Specific risks also can be incorporated into a Monte Carlo analysis to
provide a probabilistic approach toward modeling the risks.
Network Logic Risks
Network logic risks are those risks that generally occur as a result of project manage-
ment decisions that are made about the logic and sequencing of activities, determined
by the activity relationships. If a number of paths originate or terminate in one activ-
ity, there is a significantly increased risk of a delay to path activities, causing a delay