of-control events, and their associated data, that was compiled in
step 1.
The survey is conducted among construction superintendents
because they are the most appropriate source for practical information
about potential loss-of-control events. Firstly, due to their
key role in the practical execution of the work, they, more than
anybody else, are aware of the overall circumstances on site: the
composition of activities on site and their nature, the types of
activities, the number of workers involved, equipment in use, organizational
conditions, etc. Secondly, they are formally responsible
for all safety issues on site and are involved in the investigations
that follow any incidents, whether accidents or near misses.
Every respondent is asked to assess the frequency of all loss-ofcontrol
event occurrences for the activity or activities in which
they are most experienced. Two probability values are solicited
for each loss-of-control event: both a numeric and a descriptive
estimate of its likelihood (the dual values enable identification of
unreliable responses). The numeric response consists of two values:
a number and the appropriate unit of time (for example: three
times a month, once a year, twice a week, etc.). The descriptive