From Assembly Lines to Skylines: Lean Processes in Construction
By Shannon Lewis and James Turner
“Lean” is a process improvement strategy that is used in many industries because of its flexibility – not to mention its focus on saving time and money. Traditionally, Lean has roots in the manufacturing world; but, it seems this process-streamlining tool is gaining momentum in the construction industry.
The most recent Construction SuperConference and Construction CPM Conference included topics on Lean applications, and this June CURT, AGC of America, LCI and AIA hosted the 3rd Annual Lean Construction Summit. Projects ranging from power plants to roadways, hospitals and schools are using Lean concepts in an attempt to effectively control work flow, reduce waste, increase production and reduce costs.
Manufacturing to Construction
The focus of Lean in manufacturing is to make each singular step as efficient as possible and to control workflow to minimize disruptions. In construction, Lean concepts are primarily aimed at controlling the flow of work on a job to increase productivity and minimize disruptions that could negatively impact the project. The goal is to ensure that resources (such as design documents, materials and manpower) are available in time and in the proper proportion to allow for the continuous, productive and efficient flow of work.
Lean can be applied “upstream” or “downstream” of any process, and by all accounts is applicable to the most sophisticated businesses. In fact, Toyota is credited as bringing Lean into the modern industry through its use on automobile assembly lines. Many major EPC contractors, architectural firms and general contractors are now employing Lean principles.
The union of Lean and linear thinking, elimination of waste and repetitive actions makes the methods of Lean Construction aptly suited for projects with linear sequencing, such as road or high-rise building construction. Intuitively, the level of repetition in these types of projects with similar quantities of trade work to be completed in areas of equal proportion lends to the successful implementation of Lean. However, the simplicity and flexibility of Lean does not limit its application to only the obvious. Lean Construction has been applied in other areas such as industrial and commercial construction.
Lean and the Last Planner System
Lean application in construction necessitates a slight shift away from a cost only focus and instead, combines the cost focus with an adherence to a set workplan. One example of this is the use of schedule look-ahead techniques, seen in the Last Planner System of Production Control (LPS).
LPS involves the use of look-ahead schedules to forecast future “constraints” on productivity. Once the constraints are identified, managers can work with contractors to adjust work flows accordingly, averting a constraint before it arises. To ensure that cost is included in the process, it is common to employ – in addition to LPS – a tool to measure construction progress and productivity. One of the most common tools currently used is the Earned Value Management (EVM) system, which evaluates scope, schedule and cost. The primary focus of EVM is on maintaining a planned budget over time.
The Lean approach to construction progress and productivity evaluation found in LPS is referred to as Percent Plan Complete (PPC), which measures adherence to the workplan. PPC is measured by dividing total work items scheduled over the total work items completed. It’s similar to EVM, however instead of focusing on costs, PPC is focused on adherence to the underlying plan, which should inherently result in minimized costs.
Lean and Location Based Scheduling
In addition to LPS, another Lean tool being applied to construction projects is Location Based Scheduling (LBS). Also referred to as Line of Balance Scheduling, LBS focuses on the execution of specific trades, rather than on the completion of a specific piece of equipment or system. For example, rather than looking at the completion of a single piping system as a standalone task with multiple trades involved, LBS considers each trade to be a standalone task – much like an assembly line.
Instead of the task being repeated in a stationary place, LBS assumes the same trade task will be replicated over several locations. Because of the emphasis on streamlined production, LBS relies heavily on up-front quantities and reliable estimation of time required to complete work.
LBS is not limited only to “simple” issues that confront construction projects, nor is it applicable only to smaller projects. Complex industrial and commercial construction projects have utilized LBS and/or LPS to ensure sequential, streamlined completion of work and are a testament to the versatile nature of Lean thinking.
While some of the principles of Lean may appear to be common sense, their benefits can only emerge through a commitment to and a focus on improving processes. Given the current economic climate, increased knowledge of Lean principles and their potential benefits may lead to increased implementation on construction projects of varying size and scope in the future. Of course, obtaining buy-in of all project stakeholders is crucial. Without buy-in, commitment and reliable estimates of time and costs, it would be extremely difficult for either LBS or LPS to be used effectively.
Articles published in The Expert Report are the opinions of the authors and do not necessarily represent or reflect the policies or opinions of The Rhodes Group. The Expert Report may not be reproduced in whole or in part without the permission of the publisher.