|Ph.D Student||Korb Samuel|
|Subject||Investigation of Lean Management Methods in the|
Multi-Customer Construction Industry
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Rafael Sacks|
|Full Thesis text|
Multi-story, multi-customer apartment buildings represent a type of construction project that has multiple independent customers. The product is composed of both private, customized spaces particular to each apartment and shared parts of the building common to all. Projects are built bottom-up, with each trade in sequence as they proceed from lower to higher floors.
An analysis of this production system, drawing on Lean Management thinking, reveals systemic problems. Different levels of customization lead to varying work volumes, introducing inefficiencies in work flow, exacerbated by large batch sizes and waiting for skilled contractors to arrive.
The goal of this work is to understand the dynamics of implementing Lean methods in this context. The hypothesis is that implementing Lean will contribute to improved project outcomes.
A number of research tracks were pursued, most employing simulation. Simulation is an effective tool in exploring the impact of various improvements, shielded from exogenous influences. A simulation game was developed to test the effects of implementing a division of shared and private value streams, and it was deployed both as a live game and as a computerized simulation; in both cases implementing Lean in the context of two projects improved project outcomes.
A much larger simulation, called LeapconX, was developed in order to broaden the scope of the investigation and understand the market dynamics as projects (some using Lean innovations) compete for subcontractor labor. It allows the simulation of an unlimited number of construction projects, subcontractors, and apartments. The simulation can recreate years of ongoing construction projects in the same metropolitan region. The Lean improvements include reduced batch size, pull production control, and multiskilled “work cell” subcontractor teams. Different levels of market penetration of the improvements were tested, from innovators, to tipping point, to full penetration where all projects work under the new paradigm.
Here too, the improvements proved beneficial to the improved projects. For some scenarios, even projects that did not implement the improved methods saw benefits. Reducing batch size lead to dramatic improvements in project duration, as did the introduction of multiskilled teams instead of trade-specific work crews. In a mixed market, contracting with two subcontractors had a more positive effect on the project outcomes, while the implementation of pull production had a much smaller effect, tending more to improve the stability of projects rather than the duration. The simulation strongly suggests that construction companies (or entire construction markets) stand to benefit from the implementation of Lean Methods.
As with any simulation-based work, the major limitation of this work concerns the external validity in applying the findings back to the real world. Efforts were made to create a simulation that encapsulates the mechanisms and makeup of the market the simulation is based on, which minimize the gap between simulation and reality. In terms of internal validity, the simulation encapsulates the differences between the numerous systems tried within it, so that the relative differences are expected to be reflected faithfully, even if the absolute outcomes may vary from what can be expected in reality.