what is CPM
Critical path method
why understand network (CPM) schedules?
- understanding fundemental properties of network/CPM schedules and being confident in your knowledge of associated terminology helps when dealing /w/ contractors
- the schedule is only a tool, but its the primary tool available to the construction project planner
what 6 things must be accounted for in the construction project planning phase for proper managmenet of a construction project?
- The identification of specific activities of work
required and the interrelationships between those
items (precedence relationships) - The proper sequencing of the specific activities of
work to complete project asap - The time for delivery of materials and installed
equipment - The types, quantities, and duration of use of
construction equipment - The classification and numbers of workers required
and the periods of time they will be required - The amount and timing of financial assistance
required
The first two items are the scheduling portion of
construction planning, while the rest are derived
from or added to the schedule
what do you need to do to create a schedule
Identify specific activities of work required, at a level of detail that reflects the complexity you desire in the schedule—this is called the work breakdown structure, or WBS
you then need to Identify the relationships between these activities and their proper sequencing in order to
complete the project in some combination of
optimum time and budget within reasonable
constraints
what are the two types of schedules, and examples of each type
non-network schedules
- bar (gantt) charts
network schedules
- critical path method (CPM) diagrams, including:
- AOA (activity on arrow, or arrow) diagram
- AON (activity on node, or node) diagram
bar/gantt chart details
- most common non-network technique
- easy to create, read & understand
- can show logical interrelationship between activities
- can be updated to show status of project
- difficult to show/calculate effects of delays, changes,
etc. - does not provide as much useful information as a
network schedule
critical path method schedule details
- interrrelationships between activities are shown
(precedence relationships) - Critical activities determine project duration and
indicate critical path
AOA CPM diagrams
AON CPM diagrams
uses a”finish-start” relationship between dependant activities
less onerous to draw than arrow diagrams
gantt chart /w/ crit path
drawing AON diagrams
- A node or arrow diagram requires
that you assign logical “precedence” activities to
each activity. need to determine
which activities precede each given activity
identified in the work breakdown structure.
some terminology:
IPA’s - immediatly preceding activity, IPA’s assigned to each activity
sequence steps
dummy activities
CP Critical Path = the longest interconnected path
through the network the length of which equals the
project duration activities
