Pull-Driven Scheduling for Pipe-Spool Installation: Simulation of Lean Construction Technique

Abstract

Many construction processes include installation of unique materials in specific locations in the facility being built: materials and locations must match before installation can take place. Mismatches due to delay and uncertainty in supplying materials or completing prerequisite work at those locations hamper field productivity. This is illustrated here using a model of a materials-management process with a matching problem that typifies fast-track process-plant projects. The uniqueness of materials and locations combined with the unpredictability in duration and variation in execution quality of various steps in the supply chain allow for different ways to sequence material delivery and work area completion. Several alternatives are described. Their impact on process execution is illustrated by means of probabilistic process models. One model reflects total lack of coordination between delivery and work area completion prior to the start of construction; a second one describes perfect coordination. The corresponding materials staging buffers and construction progress are plotted based on output from discrete-event simulation models. A third probabilistic model then illustrates the use of the lean construction technique called pull-driven scheduling. Real-time feedback regarding the status of progress on site is provided to the fabricator off site so process steps can be re-sequenced opportunistically. This yields smaller buffers and earlier project completion and, when properly accounted for, increased productivity.

Resource-loaded piping spool fabrication scheduling: material-supply-driven optimization

“…Also, to fully implement the pull-driven supply chain management requires the commitment of all stakeholders to make decisions based on the overall project performance instead of their own interest, which is currently hard to achieve in the construction industry. This calls for the rethinking of contractual relations and providing appropriate incentives (Tommelein 1998). All these characteristics make the material supply chain in construction a dynamic process subject to various uncertainties.…”

Lean and Agile Construction Project Management: As a Way of Reducing Environmental Footprint of the Construction Industry

“…Lean production is a philosophy or strategy to minimize defects and to improve company performance [53]. Similarly, Carroll [15, p. xxxi] defines 'lean production' as "the philosophy and practice of eliminating all waste in all production processes continuously".…”

Field Trials of RFID Technology for Tracking Pre-Fabricated Pipe Spools

“…Among engineered materials, pipe spools are of particular interest to industrial projects as piping has been recognized as a very critical yet most costly and least efficient process [2]. Industrial process facilities often involve hundreds or thousands of pipe spools, many of which are unique in material (e.g., cast iron), shape, finish, and other properties (even final installation location on site).…”

“…In fact, piping has seen significant increase in the use of prefabrication and preassembly over the preceding twenty years [4]. However, piping in fasttrack projects still poses potential uncertainty in deliveries and in completing prerequisite site work, leading to "mis-matches that foul up scheduled work sequences" [2]. Under this uncertainty, materials managers rely on large buffers of pipe spools in an effort to secure flexibility in workable backlogs so that they have "at least 60 percent of all pipe on site when 20 percent of the pipe had been installed" [5].…”