Concurrently with this off-site process, construction is
under way on site. Roads are built, temporary facilities are
brought in, foundation systems are put in place, structural steel
is being erected, etc. Crews of various trades must complete
their work in each area where spools are to be hung, prior to
spool installation. When a specific set of ready-for-installation
spools is available on site, and all prerequisite work in the
matching area has been completed, spools can be installed.
Completion of an area's installation work then signals to other
trades that subsequent work can start.