Improving the making ready process - exploring the preconditions to work tasks in construction

Scheduling in construction is complex. Before an activity can be conducted, a number
of preconditions first have to be fulfilled. In Last Planner System this removal of
constraints is referred to as the making ready process. To ensure that this process is
running, the preconditions need to be known. Therefore, in an attempt to bring these
preconditions into light three construction projects have been followed. Here reasons
for non-completed activities have been collected. In total 5014 activities have been
registered whereof 1279 was not completed according to schedule. Afterwards the
non-completed activities were sorted into nine main categories. The six of the
categories are basically corresponding to the ones presented by Koskela (1999), while
the last three are an expansion of Koskela’s external condition category. The
preconditions are as follows: 1) Construction design and management. 2)
Components and materials are present. 3) Workers are present. 4) Equipment and
machinery are present. 5) Sufficient space for conduction. 6) Previous activities must
be completed. 7) Climate conditions must be in order. 8) Safe working conditions in
relation to national “Health and Safety at Work Act” have to be present, 9) Known
working conditions. Often a problem during excavations or refurbishment
assignments where existing conditions first has to be examined. One of the major and
underlying reasons to non-completed task is insufficient and even bad scheduling.
Often non-sound and out of sequence activities are selected to the Weekly Work
Plans. When conducting the schedule it is important to notice as described in
Lindhard and Wandahl (2011) that the soundness of an activity can vary over time.
By focusing on all nine preconditions a more robust schedule can be achieved. A
more robust schedule induces an increased percent planned completed level and
moreover and increased productivity.