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Radio Frequency Identification (RFID) and Building Information Modeling

(BIM); Integrating the Lean Construction Process

J. Mark Taylor, Ph.D., JD

Auburn University

Auburn, Alabama

Stephen A. Coady, MBC Candidate

Auburn University McWhorter School of Building Science

Jon Chesser

Atlas RFID Solutions, Inc.

Birmingham, Alabama

Abstract

Radio Frequency Identification (RFID) is an emerging technology that is beginning

to receive attention in the construction industry. From asset and progress

management, to the locating of underground and in-wall utilities/objects, to the

integration of RFID with building information modeling (BIM), the potential

benefits of RFID to the construction industry will be a topic that receives more and

more attention in the future. RFID, in conjunction with BIM, shows great promise

in the promotion of lean construction techniques in the construction industry. As the

technology becomes more readily accessible and the cost of implementation

decreases, this will be used on more and more construction projects. Once

contractors start adventuring into the potential that RFID has, the greater the

construction industry will benefit.

Keywords: Radio Frequency Identification, RFID, Building Information

Modeling, BIM, Lean Construction, Technology, Construction Technology.

1 Introduction

Profitability in the construction industry takes exceptional execution at every

stage of a construction project, from the initial planning and design phases, to the

closing out, and signing of the final contracts. The unique complexities and

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unpredictable nature of projects in the construction industry make successful

management a very valuable asset, but an extremely difficult chore. According to

statistics in 2006, more than half of construction firms fail within their first four

years in business [1].

The importance of productivity improvements within the construction industry

has been generating a significant amount of interest [2]. Efficient management of

assets may be considered a serious contributor to profit margins in almost every

form of business. Technological advancements have provided companies in many

different industries with more effective means for tracking and managing their

assets. One such technology is Radio Frequency Identification (RFID). Among the

many possible uses, it can be used for identification and data storage of objects,

animals, and people.

1.1 Radio Frequency Identification (RFID)

Radio Frequency Identification (RFID) refers to an automatic identification

technology which utilizes radio frequencies, or waves, to capture and transmit data

[3]. Data can be gathered and stored regarding an array of tagged items such as

objects/components, people, and animals. There is currently a vast range of uses for

the technology outside of construction including, but not limited to, product tracking

for retail chains, library usages, inventory and supply chain management, animal

tracking, health care, access and security systems, postal environment, airport

baggage management, usages in automobile keys, and toll-collection (EZ-Pass).

RFID technology uses a tag (also known as a transponder), and a reader

(sometimes referred to as an interrogator), to successfully communicate and transmit

data. The data gathered through tag and reader communication is transferred to a

host system, such as a personal computer, or connected to a business’s enterprise

system. The tag is attached to, or embedded into the object for which data is being

gathered. Tags are comprised of a micro-chip and an antenna, which are

encapsulated in a protective covering. RFID tags can have many different shapes,

sizes and protective housings. Generally RFID transponders are considered either

passive, or active. Active tags are those that have an internal power supply (a

battery). Passive tags, on the other hand, do not contain a battery [4]. Some general

characteristics of passive and active tags, as well as some pictures of each, are

shown in Figures 1 and 2.

Since passive tags do not have an internal power supply, they can only

successfully transmit data when they absorb the power emitted by a reader. Since

active tags have an internal battery source, they can actively emit a signal to the

reader in order to communicate and transmit data. Active tags, therefore, have

longer reading ranges. Active tags can also be “always on”, or programmed to

“wake up” at determined time increments (every minute, 5 minutes, 10 minutes

etc.), in order to communicate with a reader. However, long term use of the active

tag is limited by the life of its battery, a problem that can limit its usefulness in

facilities management.

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Passive Tag Characteristics:

No internal power supply

Mostly read only (data cannot be re-written)

Unlimited life

Usually smaller/lighter than active tags

Generally cheaper than active tags

Limited read range

Less data storage capability than active tags.

Figure 1. Examples and Characteristics of Passive RFID Tags

Active Tag Characteristics:

Contains internal power supply (battery)

Typically read/write (data can either be

fixed or changed)

Limited life (can be up to about 10

years)

Usually larger/heavier than passive tags

Generally more expensive than passive

tags

Longer reading range than passive

Increased data storage capability

Figure 2. Examples and Characteristics of Active RFID Tags

Electronic reading devices are used to communicate with tagged objects and

acquire data regarding those items. RFID readers or scanners can be portable

(handheld) or stationary. The readers also contain an antenna for transmitting

signals to the desired tags. The distance that a reader can read a tag will vary from

one system to another. The reading range depends more so on the reader than the

tag [5]. Some sample pictures of RFID readers are shown in Figure 3.

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Figure 3. Examples of RFID Readers

The frequency level at which an RFID system operates is also a key contributor

to a system’s characteristics and performance. Higher frequency levels will increase

the system’s reading range, as well as increase the speed at which data is transmitted

from the tag to the reader and the host computer. On the other hand, lower

frequency levels will decrease the reading range, as well as the speed of data transfer

to the reader and rest of the system [5]. The frequency bands in which RFID

systems operate is determined by each country’s respective regulatory body. The

Radio Frequency (RF) section of the electromagnetic spectrum generally spans from

3Hz (Very Low Frequency) to 300GHz (Extremely High Frequency) (Table 1).

Generic Band Name Frequency Range Comment

Low Frequency (LF) 120 - 135 kHz Short range inductive

applications.

High Frequency (HF) 13.56 MHz Worldwide common

frequency, smart cards and

labels.

Ultra High Frequency

(UHF)

433 MHz Active low power tags.

860 - 960 MHz Band with major supply chain

development activity.

Microwave 2450 MHz Active tag technology gives

range and fast data rates.

Table 1. Radio-Frequency Identification Device Frequency Ranges

There are many different varieties of RFID readers and tags which have

different performance levels for certain criteria and purposes of use. This makes it

difficult to analyze costs and historical trends. However, Niemeyer, Pak, and

Ramaswamy [6] analyzed and forecasted the downward trend in average RFID tags

and readers in a McKinsey Quarterly Report (Figure 4.) This downward trend

should help facilitate increased adoption in the future.

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Figure 4. Average cost per RFID tag and reader, Niemeyer et al, 2003

1.2 Lean Construction

Lean construction results from the application of a new form of production

management to construction. Essential features of lean construction include a clear

set of objectives for the delivery process, aimed at maximizing performance for the

customer at the project level, concurrent design of product and process, and the

application of production control throughout the life of the product from design to

delivery [7].

The highly competitive nature, combined with stringent time and cost budgets

that are common in construction, require participants within the industry to

constantly seek improvements in productivity [2]. Productivity can be measured in

many ways, but is often defined as a measurement of the quality and/or quantity of

output, in relation to the input required to produce that output. Among the many

aspects critical to achieving better productivity, is a company’s ability to manage its

assets and resources successfully. The efficient allocation, supervision, and

motivation of on-site employees may be an important aspect of management for

construction companies that employ a large number of craft workers. Effective

management of building materials both throughout the supply chain, and while on-

site, may be considered another important task for construction projects. The

knowledge regarding the whereabouts of important tools and equipment on large-

scale projects can affect productivity.

The demand for increasing productivity and safety throughout project delivery

has stimulated the exploration of new technologies that may be implemented to

improve productivity of construction work. Many other industries have utilized

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RFID technology for multiple purposes, perhaps most often for the tracking of

products, and inventory systems management [8]. Currently, the prospective

opportunities for RFID within construction are quite vast. Areas of lean

management that can potentially utilize RFID technology and implementation

include:

Tracking and tracing of components vehicles, parcels etc

Inventory Management

Product ID - using the right component and device

Maintenance of service systems

Track recording of components

Incorporating RFID into design

The number of studies and experiments that have looked at different uses of the

technology has significantly increased recently. From asset and progress

management, to the locating of underground and in-wall objects and utilities, the

outlook for potential benefits in productivity through the implementation of RFID in

the construction industry is starting to look positive [9].

Organizations such as FIATECH, CICA, ERA Build, and the Construction

Industry Institute (CII), have analyzed the technology’s potential within the

construction industry through various pilot studies, demo applications, journal

articles and papers, in an attempt to map out key processes and functions that could

possibly benefit from RFID. ERA Build’s Final Report on RFID in Construction [8]

noted the following as the main drivers for the construction industry:

Tracking and tracing of components, vehicles, parcels etc.

Supply Chain Management and Logistics - efficiency

Product ID - using the right component and device

Maintenance of service systems

Track recording of components

Although interest in RFID in the construction industry has increased

significantly over the past decade, the number of companies that have adopted the

technology for continued use within their operations remains somewhat stagnant.

According to the same ERA Build Report [8], some of the main preventers of

widespread construction industry adoption include:

Immature application of advanced logistics systems and the absence

of information and identification systems in the construction industry.

Lack of awareness of RFID's potential in the construction industry.

Low RFID-knowledge and awareness in the construction sector

Lack of robust RFID-initiatives in the construction industry

Lack of successful RFID-implementation cases that thoroughly

shows its potentials

The traditionally less industrialized construction industry and its

relatively negative attitudes toward new innovations and technology

A National Institute of Standards and Technology (NIST) white paper entitled

Smart Chips in Construction, noted recommendations for further research that is

needed before advances are to be made in implementing RFID in the construction

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project life cycle. Among other requirements, the paper calls for increases in RFID

pilot studies within construction. For increased promotion of RFID solutions in the

construction industry, ERA Build’s final report [8] stated that “the primary need is

for exchange of knowledge and project RFID sampling to increase contractor and

owner awareness of the potential savings.” It will become increasingly important to

continue to evaluate different reasons for RFID adoption, and the implementation

processes that are undertaken by those companies which utilize the technology.

2 Background

Literature on RFID and its potential within the construction industry has mainly

arisen within the last decade or so. The Construction Industry Institute (CII)

conducted a workshop regarding RFID and possible implementations in construction

in 1998 [3]. The workshop divided into four groups consisting of material

management, engineering/design, maintenance, and field operations. Each group

identified many potential RFID applications within their delegated areas of

concentration. A lengthy report was written in 2006 regarding RFID and

construction [8]. Contents of that report include: a brief introduction into RFID

technology; the uses and benefits found in other industries; Applications to the

construction industry, as well as a list of cases and pilot studies that have been

performed globally; and the driving forces for RFID, and challenges faced that may

deter or delay industry-wide acceptance. There have also been a number of brief

articles written recently which express RFID’s lurking presence within the

construction industry. The prospects for improved productivity through its

implementation, and some problems that have hindered its adoption into

construction are also addressed in those articles [9, 10]. The positives and potential

negatives of RFID uses for supply chain management are assessed in articles by

Wang [11] and Santosh [12], which explore new management processes, as well as

the legal aspects and concerns for confidentiality of supply chain processes

information, resulting from uses of RFID.

Actual data producing research and experimental testing of RFID utilizations

for improved efficiency in construction processes have been performed

predominantly over the last few years. One significant study has been done through

a collaborative research method performed jointly by Samsung Corporation,

Sungkyunkwan University, and Doalltech Corporation [13]. The study concentrated

on RFID and 4D CAD (Computer Aided Design) technologies for improved

progress management of structural steel work on high-rise buildings in Seoul,

Korea. RFID was implemented from the beginning steel manufacturing phase, and

tracked throughout the delivery and receiving of materials phases. Invoicing

practices and on-site management of the steel inventory, from receiving and storing,

to the actual erection of the pieces, were tracked and analyzed for three projects.

Two of the three projects implemented the new technologies, whereas the other

followed current methods and practices for managing the supply chain and

construction processes of structural steel components. Although there were plenty

of positives resulting from the study, some apparent signs of the immaturity of the

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technology were reported. A lack of confidence in the technology was expressed by

those who were unfamiliar with RFID. Manufacturers of the steel were the most

reluctant to adopt the process because of the added work of attaching the RFID tags

and a lack of benefits on their end. On the positive side, increases were reported in

productivity for time spent inputting data, unloading steel, time spent in stockyards

of factory and construction site, and the general contractor and subcontractor’s daily

reports. An overall process time with the new technologies was shown to have 17%

more time efficiency than the conventional process for supplying and erecting the

steel [13].

A materials tracking field test that was sponsored by the Construction Industry

Institute was performed by professors and graduate students from The University of

Texas at Austin, University of Kentucky, and University of Waterloo, along with the

collaborative help of local industry partners, and RFID solutions vendors. The

studies were done on two projects: A $750 million power plant in Rockdale, TX,

constructed by Bechtel; and a 550 megawatt Portlands Energy Center in Toronto,

Canada, contracted by SNC-Lavalin Constructors Inc. Both of these studies also

produced positive data and worker feedback regarding RFID implementation [9].

Through comparing the time it took to locate materials with the old method, to the

automated method with RFID/GPS technology, the study found that the average

time to locate materials with the manual method was 36.8 minutes, and the time it

took with the automated method was 4.6 minutes. In an ENR article, Paul Murray,

the site manager on the Canadian project noted “Instead of having a $75-per-hour

pipefitter go out and look for [a component], we had a $14-per-hour student intern

ID it, and then they would go out and get it” [9]. Murray also commented on the

performance of the technology and implementing it full time: “We had two identical

boilers…Once we saw the use of it we weren’t going to let one boiler fall behind”

[9].

Research on the use of RFID in the concrete curing processes has also

developed over the past fifteen years. In 1995, an article in the Journal of

Construction Engineering and Management proposed three potential uses for the

technology within the construction industry [5]. The concepts developed in that

article pertained to concreting operations; cost coding for labor and equipment; and

material control. The article mentioned the potential ability of RFID to take

incremental temperatures, but for the most part concentrated on proposed systems

for tags to be externally applied to concrete trucks and concrete test cylinders in

order to locate and identify them. Another article discusses external applications of

RFID to concrete was recently written in the past two years [14]. The article

analyzes the tracking of engineered-to-order components such as precast concrete

members throughout the supply chain with RFID. The article harps on the

automated data collection that RFID provides which workers try to avoid, as well as

the durability of the technological equipment, but still only mentions external

attachment to objects, as the cheaper passive tags better suited their budget.

A study regarding the implementation of RFID tags inside concrete specimens

was performed by Wang et al. [11]. One goal of the study was to develop a web-

based quality inspection and management system for improving the availability and

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communication of inspection data results to those involved in the construction

process. The quality management system that developed was designed to quickly

gather data in material test lab areas and relay that data, via the internet, to other

parties of interest such as the owner, consultant firm, customers, suppliers and

contractors. Another important goal of the study was to determine through field

tests, whether the insertion of an RFID tag inside concrete would influence the

strength of a specimen. Proper placement within a specimen was also discussed.

Conclusions regarding the web based system claimed that it “enhanced the

construction quality inspection and management performance in…working

efficiency, reduction of operation cost, customer satisfaction enhancement, and time

saving in inspection operation and management progress” [11]. The study also

found that the placement of RFID tags inside concrete specimens did not influence

the strength of those specimens. An important note to add is that the research

expressed the importance of the insertion position of the tags within the concrete

because if the tag were too deep, it would be unreadable [11].

The Michigan Department of Transportation (MDOT) performed another study

and Dr. Andrew J. DeFinis wrote a white paper on the research entitled “Concrete

Maturity Testing in Michigan”, in February of 2004 [15]. The test was performed

because the MDOT wanted to develop a provision that would allow contractors in

Michigan to use maturity testing to approximate the strength development of

concrete pavements. The maturity concept estimates the strength development of

concrete by taking into account the combined effects of temperature, and the time a

specimen was poured. Data on time and temperature, gathered through RFID

wireless tags located within the concrete, was entered into an equation known as the

Nurse-Saul equation. The Nurse-Saul equation is used to estimate the strength of

concrete in pounds per square inch. Standard concrete cylinders were also tested

and the compressive strength was compared to the maturity estimates. The study

concluded that the Concrete Maturity Monitoring System measurement results were

within 4-11% of the concrete cylinders. Differences in results were expected to be

reduced if adjustments could be made to the method of curing the concrete

cylinders. Every RFID tag placed on the project worked.

Currently a study is underway which will utilize RFID tags for concrete curing

information on the construction of the Freedom Tower in Manhattan, which is being

erected on the location where the World Trade Center towers once stood [16]. The

tags are being utilized on almost every major concrete pour including footings, core

walls, elevator shafts, stairs wells, and all mechanical spaces. Identec Solutions AG,

Lustenau, Austria is providing the tags, and the article reports that approximately

20,000 active RFID tags will be used throughout the 1,776-foot tall tower and its

surrounding structures.

Research regarding the monitoring of labor inputs, and uses of new technologies

to compose real-time assessments and make necessary adjustments to labor force

allocations, has become an increasingly attractive topic in construction [17]. Studies

performed by Navon and Goldschmidt in 2002 explored possible technologies that

could be used for automated location measurement. RFID played a significant role

in their design of a performance measurement system, which proposed to determine

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worker’s locations at certain time intervals, and then measure the amount of work

completed at those locations, or “work stations”, to establish a metric of productivity

[17]. In 2003, Navon and Goldschmidt put their performance measurement system

through a series of smaller, preliminary field experiments, in order to analyze the

systems accuracy in measuring worker efficiency. The results determined that the

“prototype successfully measured the time workers spent performing their tasks with

an accuracy level of plus or minus 10-20%” [18]. The study also mentioned the uses

of RFID technology for determining employee locations after accidents have

occurred on a site.

The amount of literature pertaining to RFID and the employments to the

construction industry has significantly increased since the year 2000. There are

numerous reports that explain the current uses in other industries, and anticipate that

possible applications within construction will increase in the future. A handful of

data producing experiments have been performed for asset tracking and

management, particularly for materials, equipment labor and concrete curing, with

hopes of determining potential improvements in the project delivery process.

3 Case Study

This specific case study pertaining to RFID applications within the construction

industry was performed on a power plant expansion project being constructed by

Bechtel Corporation in the Northern United States. The expansion project consists

of two coal-fired steam-turbine generating units, as well as supporting facilities, and

related civil work. The contractor’s scope of work consists of engineering,

procurement, construction, and start up. The project will cost an estimated $2.15

billion dollars, with construction scheduled from 2005 to 2010. Of the two units,

one is scheduled to begin operation in 2009, and the second is scheduled to begin

operation in 2010.

3.1 Site Layout and Material Lay-Down Yard

The original project site utilization plan for the project delineated one large area

of the site to act as the lay-down yard for construction materials as they were

brought onto the site. A substantial amount of site work was necessary in order to

prepare the land for construction of the new expansion facilities. The earth removed

from the shoreline area where the new expansion project was to be constructed was

placed on the proposed materials lay-down area. Afterwards, it was found that there

were issues with the underpinning soils and the majority of the land would not

suffice for material storage. Approximately 60 acres of land intended for material

storage was determined to be unusable.

As the original material lay-down yard was unsuitable, the construction

management team was forced to reorganize and utilize alternative land for the

necessary material storage for the project. Through arrangements with landholders

to the south of the construction site, additional land was acquired for material

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Figure 5. Material ID code

storage needs for the duration of the project. The yards now stretched from North to

South and the distance between the two farthest most yards was approximately three

miles.

3.2 Materials Management Process without RFID

The materials management process for the project is comprised of a series of

activities or processes that ultimately lead to the installation of a component into the

facility. A majority of the steel and piping for the project was received on site via

truck. Some components for the project were shipped by boat.

As materials are delivered to the site, they came with a packing list, which

detailed the contents of the shipment, including where it came from, contact

information, date of shipment, etc.

Each component of material comes

with its own specific material

identification code for the project.

The material ID codes are written

on the surface of the components,

and are comprised of a series of

numbers and letters (Figure 5).

The entire receipt process and the

entry of items into the materials

management database was

performed with a paper based

manual method. The materials are

accounted for and manually entered into the materials management database system,

so that construction activities could be coordinated depending on the availability of

materials.

The components are then taken to the lay-down yards and placed within a

specific grid. Caldas et al. [19] refer to this stage as “Sorting.” The components are

grouped within grids according to characteristics and material identification code.

Different groups of materials are assigned a color scheme. Specific colors and

twisted combinations of colored flags are attached to the respective groups of

materials for future identification and locating purposes.

Materials are stored in the lay-down yard until needed for installation. When a

construction crew or trade is prepared to construct a certain section of the facility,

the necessary materials have to be retrieved from the lay-down yard. For this, a

superintendent coordinated with a field engineer and communicated the plans for

assembling a certain area of the facility. The field engineer would generate a

material withdrawal request (MWR), which listed all of the necessary materials that

the superintendent’s crew needed in order to complete the specified scope of work.

The MWR is sent to the Materials Management staff, where they develop a “pick

ticket”. The pick ticket lists the materials needed, along with the respective lay-

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down yard and grid location of the component. The Materials Management team

then gives the pick ticket to the respective staff so that they can locate the materials.

Workers would take the pick ticket to the lay-down yards and visually locate the

materials that were needed for installation. Once located, the components were

flagged, organized, and staged so that the pick-up process of those materials would

be easier and more efficient. The materials would be loaded and taken to the

construction area where they were turned over to the construction team. Once the

materials had been turned over to the construction team, the receiving foremen

would sign off on the materials to assure that they have received them.

The sequence of activities in the materials management process for this project

was similar to the one described in the pilot test performed by Caldas et al. [19], in

which the impacts of utilizing Global Positioning Systems (GPS) for the locating of

materials was measured (Figures 6 and 7).

Figure 6. Material Management Process [2].

3.2.1 Problems Presented With the Manual System

The issues presented for materials management on Bechtel’s power plant

expansion revolve around the ability of personnel to locate and flag specific material

items (Flagging), so they may be organized for convenient pick-up and transporting.

When materials required for installation are not ready at the time they are needed,

installation crews may become idle and nonproductive, which can increase craft

labor hours up to 16-18% [20].

The sheer volume of materials required on the construction site presented the

materials management team with several problems. The $2.15 billion power-plant

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Figure 7. Responsibilities and Paperwork for On-site Material Management Process

project is comprised of an incredibly large number of intricate components of steel,

piping, and other structural and functional components. Individual piping pieces can

become very difficult to identify when they are closely stacked together in areas of

what can be thousands of square meters per lay-down grid. Additionally, there is a

limited number of colors that flagging comes in, and it can become difficult for the

picking crew to decipher which materials are for their specific load if there are

multiple loads marked with the same colored flagging (Figure 8).

Figure 8. Piping and structural steel lay-down yards

Superintendent

•Ready to construct

Field Engineer

•Develops MWR (list of needed materials)

Materials Management

•Develops pick ticket

Trade Workers

•Take ticket and locate, flag, and organize/stage

materials for pick-up

Communicates to

Field Engineer.

Sends MWR to

Materials Mgmt.

staff.

Sends pick ticket to

respective trade staff.

Materials are loaded

up, taken to site, and

workers sign off

on receipt

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The arrangement of the material yards is also a factor which can contribute to

decreased efficiency in the flagging process, as well as the rest of the material

management process. The farthest lay-down yard was almost three miles from the

construction site. Therefore, minimal time spent at the storage yard was desired

since it took a significant amount of travel time to get there and back.

Another factor affecting the material management process was the weather

conditions. Extremely cold temperatures, combined with rain and snowfall, were

the main areas of concern regarding severe weather that could affect construction

productivity. The flagging process was made much more difficult after heavy

snowfall for the obvious reason that the materials would get covered in snow and the

material ID codes must be uncovered, with shovels or by hand, in order to properly

identify. Snowfall could complicate and delay the delivery of materials to the

construction site further if a significant amount of snow was received after the

flagging crew had already located and flagged the necessary materials. The flagging

process must essentially be repeated by either the flagging crew or by the picking

team when they come to load the items for transportation to the construction site.

3.3 Experience with Automated Systems, Lean Construction, Six

Sigma, and Decision to Implement

Due to the problems associated with the manual tracking system, the decision

was made by management to implement a full scale RFID/GPS based system for the

entire on-site materials management process. ERA Build [8] noted that long

implementation time and difficulty in obtaining the skills and knowledge on the

technology can be key operational and technical barriers that face companies in

adopting the technology. This was the company’s first full scale application of the

technology. The big decision to invest and employ the technology on a large scale

was made less difficult, in large part, due to the company’s previous participation

and involvement in pilot tests. Bechtel hosted an academic study pertaining to RFID

technology on one of its construction sites in 2005.

Bechtel’s field test was performed over approximately three months on a twin-

boiler project in Rockdale, Texas. Chief sponsors of the pilot were the Construction

Industry Institute (CII) and FIATECH, and the research team was comprised of

about two dozen individuals representing universities, construction firms, institutes,

and technology vendors [9]. The field tests compared the times of the typical paper

based manual method of locating steel items, to the RFID/GPS based automated

method for tracking down components in the lay down yards. The trial results found

that the average time taken to locate a specific component with the manual process

was 36.8 minutes. The average time taken to locate materials with the automated

method was 4.6 minutes. Also, when using the manual method, 9.52% of material

components “were not immediately found,” compared to the 0.54% of the

automated method. The research team regarded the success rate of the automated

system to be quite significant considering the fact that the failure to locate critical

items can lead to costly slowdowns, and sometimes even re-procurement [9].

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3.3.1 Six Sigma Management Strategies

Bechtel utilizes Six Sigma management strategies throughout their business

processes and construction projects. Six Sigma is a quality based business strategy

which aims to decrease the amount of defects, or errors, or failures that a company

might encounter throughout its business processes. Defects are known as anything

that may lead to customer dissatisfaction. Six Sigma aims to develop quantifiable

business improvements via statistical analysis of data. The process can be described

as: “Six Sigma methodology of problem solving integrates the human elements

(culture change, customer focus, belt system infrastructure, etc.) and process

elements (process management, statistical analysis of process data, measurement

system analysis, etc.) of improvement.”

The experience gained through the field study proved to be valuable for

Bechtel, in regards to developing future applications. Not only did the field studies

produce valuable data for statistical analyses, but the relationship that was gained

with the technology vendor during the field tests, was able to be continued, and

developed into a business relationship for their full scale implementation.

3.3.2 Technological Specifications: Tags and Readers

The tags utilized in this full scale implementation were active RFID tags. These

active tags continually “wake up” and send out their ID information at pre-

configured intervals (i.e. every 1 second, every 2 seconds, every 10 seconds, etc.).

The active tags are Ultra High Frequency (UHF), and they operate on a 915MHz

frequency level. The lifespan of the tags is generally five years. The physical

dimensions of the tags measure about 5 x 1 x .85 inches and weigh about 50 grams.

Tags with these characteristics and reading ranges cost approximately $25(US) each.

The reading units utilized in this application were a combination of RFID reader

and Global Positioning System (GPS) receiver. The readers were mobile, handheld

computers, or personal digital assistants (PDA), suitable for field readings. The

readers’ operate with Microsoft Windows. Approximately six handheld readers

were utilized on the entire project; usually a team (i.e. iron-workers) would have its

own reader which was designated for them each day. RFID/GPS readers such as

those utilized in this study currently cost approximately $5,000(US).

The automated materials management process also used barcode scanners for

association purposes. The scanners were mobile, handheld devices that utilize

Bluetooth technology. The scanners operate on High Frequency (HF) radio waves

at a 13.56 MHz frequency level. The scanners are rechargeable. The physical

dimension of the barcode scanner is about 4.8 x 2 x 1.3 inches and weighs 132

grams (about 0.3 pounds). These barcode scanners currently cost around $450-

$500(US). (Figure 9).

Server software is also required for the system and it can cost approximately

$35,000 - $50,000(US) depending on the software and the vendor.

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Figure 9. System Hardware

3.4 Implementing the RFID/GPS Based System

The RFID/GPS based materials management process was not implemented

from the beginning of the project. It was only after the problems mentioned above

arose, that the decision to implement the automated tracking system was made. At

that time, around 65-75% of the materials for construction had already been

delivered to the site. Having the majority of the materials on site meant that the

materials management process would have to be retro-fitted with the technology.

Roughly 6-10 employees were assigned the task of attaching tags to materials in the

lay down yards, and associating those tags to the specific material piece in the

management system. This project tagged 20,000+ unique material components with

RFID. Approximately 12,000 tags were utilized for this project, as tags are

reusable.

3.4.1 Attaching and Associating RFID Tags to Materials

RFID tags were attached to the material components with plastic zip ties. The

holes present on the RFID tags make this a simple process and the tags can attach to

materials through anchor bolts in the materials, or by simply wrapping two ties

around the materials and pulling tightly (Figure 10.).

Once the tags are attached, they must be associated with the respective material

to which they are attached, for future tracking purposes. Some materials arrived on

site with a barcode label that indicated the component’s material ID. Others did not

have barcodes attached, and their material ID would be written on the exterior of the

component.

If the material component had been delivered with a barcode label, then the

association process becomes very simple and almost instant. The barcode label on

the material component is simply scanned along with the barcode label on the RFID

tag attached to it. The barcode scanner is able to instantly transmit the material ID

and RFID tag’s ID into the RFID reading device wirelessly via Bluetooth

technology. Once the material ID and tag ID had been input into the RFID reader,

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the worker could hit “associate” on the RFID reader to initiate communication with

the tag while next to it, and that specific RFID tag’s ID would then be linked to the

material component on which it was attached. Once the tag was associated, the

workers would hit the “locate” button on the RFID/GPS reader, and the

component’s latitude and longitude is stored in the reader. The tag had been

associated to the specific material component and now that specific material

component was ready to be tracked. When items arrived with barcode labels, the

association process, after the tag had been attached, was very simple, and

completely automated. The association process takes approximately 10 seconds.

Figure 10. Associating materials with and without barcodes ID

When material components did not have an attached barcode label, the

association process was changed slightly. Workers would still scan the barcode on

the tag to input the tag ID into the RFID reader, but had to type in the material’s

unique material ID, which was stamped or written on the exterior of the item, into

the RFID reader. The worker hits “associate” on the RFID reading device so that

the material component would now be linked to the tag (Figure 10). Again, the

worker would hit “locate” to assign the material a latitude and longitudinal position.

When employees typed the material ID into the handheld devices manually, the

elements of human error become possible. Problems such as entering the material

product ID incorrectly were more prone to happen in this case.

3.4.2 GPS Mapping and RFID Tag Locations

Before the system was implemented, the lay-down yards throughout the site

were geo-coded, mapped and entered into a geographic information system (GIS),

which divides the yards into their respective coordinated grids. As Torrent and

Caldas [20] explained, GPS receivers can be set to transform collected systems into

a coordinate system. The default latitude and longitude degrees for a global system

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can be transformed into a “local projected system” so that it “simplifies the

implementation of the localization mechanisms by providing coordinates in

fundamental units of length, such as meters [20]. An image of the digital lay down

yard on an office desktop easily identifies the material and its location in the lay-

down yard (Figure 11).

Figure 11. Digital map of lay down yards with grids

3.4.3 Tag Item Location with RFID/GPS System

Because of costs and other issues, attaching individual GPS receivers to each

piece of material, when there are mass amounts of material items, has been deemed

an infeasible option for the purposes of locating construction materials [20].

Therefore, the project in this study utilized six RFID reading devices that were

equipped with GPS receivers, and the material components were tagged with RFID

tags. The GPS receivers are able to determine their own location at any given time.

The active RFID portion of the reader could then be utilized with localization

methods, which are algorithmic based location projections based on strength of

signal and reader location, as described by Torrent and Caldas [20], for the projected

locations of the RFID tagged components that were within reading range of the

reader. Periodic updates are made in order to update the projected locations of

materials. To perform a periodic update on a lay down yard, an employee would

either walk or drive around the perimeter of the lay down yards with an RFID/GPS

handheld very slowly, in order to allow the reader to pick up all tags within the yard.

Once the updates are complete, the RFID readers are brought back to the materials

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management office and placed in their “dock” (Figure 12). When placed in a dock,

the handheld reader automatically transfers new data, gathered by field activity, into

the main materials management database.

Figure 12. Docked RFID/GPS Readers in Office

3.4.4 Automated Locating Process

With the RFID/GPS system in place, the goal is to make the material locating

(flagging) process much easier and faster. With the automated system in place, after

the Engineer has developed a material withdrawal request (MWR), the materials

management office staff generates a pick ticket packet which included a list of the

required materials and each item’s specific yard and grid, as well as a supplemental

image, which would give the workers the approximate location of each component

within their respective grid, assigned by the GPS/RFID localization methods (Figure

13). The workers go to the correct lay down yard and grid, and go approximately to

where the printed map had indicated the material’s location to be within that grid.

Once in the area, the workers utilize the RFID/GPS reader to narrow in and find

the component. The reader could pull up two different modes for finding the items.

The map view utilizes the GPS portion of the reader. The digital map of the yard

can be displayed on the handheld screen and the GPS receiver will show where the

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Figure 13. Pick ticket list and map of projected locations

employee is standing, and the projected location of the material. The employee’s

positioning on the screen is represented by a blue dot, and the material component is

represented by a red dot (Figure 14). Another method was to set the reader into

what was referred to as the Geiger counter mode. A Geiger counter is an instrument

that can detect and measure radioactivity [21]. The Geiger counter mode of the

reader allows the worker to communicate only with the specific tag that is desired.

The Geiger counter can be utilized within 150ft proximity from the tagged

components. As the worker moves with the reader, the GPS receiver determines and

gathers information on the location of the reader. The RFID portion communicates

with the desired tag, and the reader utilizes localization methods based on the

positions of the reader (gathered by GPS), and the received strength of signal from

the desired tag at those positions (gathered by RFID). A compass pointed the

employee in the direction of the tag with which the reader was communicating

(Figure 14). The reader also emits audible “beeps” that becomes more rapid and in

closer intervals as the reader gets closer to the tag, and the signal strength increases.

When the reader is within a couple of meters from the tag, the compass would

change to a cross-hair and display the words “WITHIN RANGE” (Figure 14).

Once the reader is held next to the correct tag/material, the blue column bars fill

the graphing area displayed on the screen (Figure 14). The worker then examines

the material and the material ID, which is written on the exterior of the component,

to assure that the material ID on the item matched the material ID listed in the pick

ticket. As before, once the materials had been located, they could be organized,

21

prepared for loading and transported to the construction area. The construction crew

would sign off on the materials to assure that they had been received for installation.

After materials were delivered, the tags would be removed from the material and

placed in a steel bucket. The tags could then be recycled back to the material

management office, where they would be disassociated from the material to which

they were originally attached, and stored for possible reuse.

Figure 14. Reader in Geiger, Map, and Within Range

3.4.5 Performance of the System

The performance of the technology was satisfactory and it was noted that there

were very few malfunctions. One issue of concern was whether or not the

technology would perform in very cold temperatures. They found that the system

worked down to -26 degrees Fahrenheit. Also, it was mentioned that at extreme

temperatures below that mark, the readers were affected by the cold before the tags,

so workers would warm the readers by means such as holding the readers inside

their coats. Tags could easily be read through a couple of feet of snow.

Although the tags were durable, moving materials or placing heavy materials on

top of each other can sometimes damage the tags. It was proven that if the outer

shell of the tag has been damaged, but the internal battery and antenna device had

not been affected, the tag maintained its readability function. For assurance

measures on this project, tags that were damaged in any way were replaced, and new

tags were attached and associated to the material.

During the initial stages of implementing the RFID system, a few tags were left

attached to their respective material components after the materials were installed in

the facility. When readings were attempted on the installed materials from inside

the facility, workers found that the surrounding structure, which was comprised of

mass amounts of steel, did not facilitate successful communication between tag and

reader. Therefore, management decided to remove the tags for recycling once the

materials had been received and signed for by the receiving foreman.

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3.4.6 Results and Future Plans

Jim Rogers, the Six Sigma Black Belt for the project, commented on the current

standing of the automated system and the effects that Six Sigma and RFID/GPS

have had on the project: “We used all the (RFID) tools, and the application of LEAN

to eliminate a wasteful flagging step…We now send the loading crew straight to the

material rather than having another pair of people go ahead to make sure they can

find the material, flag or identify it with colored ribbon, in order to optimize the

loading crew’s time, and that of the crane. The quantified savings were centered on

eliminating the flaggers, although many other benefits are known, e.g. schedule,

supply chain risk, staging space savings.”

The RFID/GPS based system utilized on the project described in this case study

will continue to be used by the company for upcoming projects of similar type. Two

new projects will utilize the same technology are recently getting underway in Ohio

and Illinois. In this case study, the automated system was retrofitted to the existing

materials already on site and in the lay down yards, however, future applications

will aspire to implement the system so that the materials will be tagged with RFID

before they arrive on the project site. When commenting on further developments of

RFID based solutions, and the processes that will be impacted and changed, Rogers

noted: “The whole supply chain, from engineering through procurement, field

material management, construction, and some selected components (that need

maintenance) by the customer. We started with the greatest need, with a compelling

business case, and we will build from there.” The future goals will be to track

different components throughout the entire supply chain, as well as while on site,

and selected components that will need maintenance in the future, could also remain

tagged with RFID after installation to facilitate easier identification for maintenance.

To do this, it will require increased cooperation and coordination with suppliers,

customers, and others involved in the supply chain process.

4 Conclusions

Although RFID technology solutions for the construction industry are still in the

early stages of development, case studies are showing that custom solutions can be

proven beneficial for some construction companies’ processes. Solid business cases

for RFID based solutions that can be uniformly applied across the construction

industry remain to be seen. This may be in large part due to the fact that each

construction project will be unique to a certain degree, whether it is by size,

complexity, life-cycle, geographic location, etc. Also, depending on the size and

structure of a construction company, it may or may not be able to accommodate, and

assign overseers for the adoption of a new technological system. Those companies

that remain curious and open minded towards the technology will be more likely to

realize potential benefits. If construction companies are willing and able to put forth

the effort and investment of time that might be necessary to familiarize themselves

with the technology (different variations and combinations), then those companies

will be the ones that begin to realize the potential for applications within their own

23

processes and project delivery methods. The experience a company gains with the

technology through sponsored academic studies proves to be valuable for both

statistical data, as well as for developing a working relationship with the technology

vendor. These experiences, combined with the companies’ excellent ability to self-

analyze and pinpoint weaknesses within their current processes, ultimately led to a

full scale implementation of an RFID/GPS automated system, which was aimed at

completely eliminating an entire step within the materials management process.

Another technology that may facilitate the transition from tracking field

materials to in-place materials is in the area of building information modeling

(BIM). As more and more projects are becoming BIM based, a natural progression

will be to link the RFID solution to the BIM solution. This would mitigate the

problems currently encountered with reading tags of in-place materials and the loss

of data once a battery ceases to operate. If the owner receives an as-built model, the

facilities management process can eventually be streamlined. This is truly in line

with the lean construction philosophy.

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