Other Scheduling Methods - Construction Project Scheduling and Control - page 323

focus of additional recorded data relates to the restraints between activities, includ-
ing noting the reason why such are provided in both a code format and a freeform
description, there are five areas of additional information that may be recorded and
used for further calculation in the full implementation of RDM. These five classes of
information include:
1. Events : RDM restores the concept of a discrete event at the start and finish of an
activity, similar to that of the original ADM format, but it adds the concept of
events within an activity whenever the logic restraint between activities relates
to the completion of some portion of one activity before the start of another
activity, or the completion of one activity before the start of the final portion
of another activity. Events may also be freestanding from an activity as true
milestones and as such do not have a “start” date and a “finish” date but,
rather, an “occur” date. A freeform description or “title” may be assigned to
an activity, as may be event codes that are analogous to activity codes supported
by many software products.
2. Duration : RDM records and utilizes several of the assumptions relating to
activity durations. These include the calendar and several other assumptions
that are either recorded for all durations via a system setting in some software
implementations or are ignored by others that provide only one option. While,
in most cases, this data will not affect the calculated output for an initial CPM,
they may impact the calculated output for an update, especially if the progress
of the past period is not as initially planned. The first consideration is to recog-
nize that durations between activities (known as lag in the PDM format) are
just as important as the durations of activities and that the duration calendar
and other duration codes may be recorded for each such duration. Duration
codes include the following:
a. P/C/K (Progressed/Clocked/ClockCheck): Durations may indicate work to
be performed, which must then be monitored during the course of subse-
quent updates, or may merely represent a period of time that will continue
without further monitoring once work commenced. Curing of concrete is
one such example. While actual labor may be required (such as to provide
periodic spraying with water), the completion of the activity may be calcu-
lated without further monitoring of its progress. The ClockCheck option is
designed for a special situation in which monitoring of the progress is not
required (or, in many cases, not possible) but completion may and should
be noted before the scheduling of successor activities occurs. Approval of
a shop drawing is an example; once the drawing is submitted, the software
will automatically count down the duration of the approval period but will
stop at one day for manual verification that the approval has been sent by
the engineer to the contractor.
b. C/I/S (Continuous/Interruptible/Stretched): Where an activity is subject to
a restraint to its start and also to its finish (such as by separate SS and FF