Mobile Construction Supply Chain Management
Using PDA and Bar Codes
H. Ping Tserng
∗Department of Civil Engineering, National Taiwan University, Taipei, Taiwan 10600
Ren-Jye Dzeng
Department of Civil Engineering, National Chiao-Tung University, Hsinchu, Taiwan 30050
&
Yu-Cheng Lin & Sheng-Tai Lin
Department of Civil Engineering, National Taiwan University, Taipei, Taiwan 10600
Abstract: Construction project control aims to effec-tively obtain real-time information and enhance dynamic control by utilizing information sharing and connecting involved participants of the projects to reduce construc-tion conflicts and project delays. However, extending the construction project control system to job sites is not con-sidered efficient because using notebooks in a harsh envi-ronment like a construction site is not particularly a con-ventional practice. Meanwhile, paper-based documents of the site processes are ineffective and cannot get the quick response from the office and project control center. Inte-grating promising information technologies such as per-sonal digital assistants (PDA), bar code scanning, and data entry mechanisms, can be extremely useful in im-proving the effectiveness and convenience of information flow in construction supply chain control systems. Bar code scanning is appropriate for several construction ap-plications, providing cost savings through increased speed and accuracy of data entry. This article demonstrates the effectiveness of a bar-code-enabled PDA application, called the mobile construction supply chain management (M-ConSCM) System, that responds efficiently and
en-∗To whom correspondence should be addressed. E-mail: hptserng@
ce.ntu.edu.tw.
hances the information flow between offices and sites in a construction supply chain environment. The advantage of the M-ConSCM system lies not only in improving the effi-ciency of work for on-site engineers, but also providing the Kanban-like visual control system for project participants to control the whole project. Moreover, this article presents a generic system architecture and its implementation.
1 INTRODUCTION
The construction industry is one of the most complex in-dustries because the total development of a project nor-mally consists of several phases requiring a diverse range of specialized services and involvement of numerous par-ticipants. Therefore, it is not easy to control and man-age construction projects effectively. A real-time mon-itor and control system for construction projects may be necessary and helpful in completing the projects and to meet budget and deadline. With the advent of the Internet, web-based information management solutions allow information dissemination and sharing among all the project participants. Usually, construction managers and on-site engineers need access to the construction site to manage the project because most of the construction
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2005 Computer-Aided Civil and Infrastructure Engineering. Published by Blackwell Publishing, 350 Main Street, Malden, MA 02148, USA,
projects are operated in construction sites. Nowadays, desktops and notebooks have become essential tools in construction management. However, the current desk-tops and notebooks are not suitable for the construction sites because of inconvenience in carrying. On-site en-gineers generally handle various types of digital infor-mation, such as drawings, specifications, checklists, and daily reports. They usually use sheets of paper and/or field notes. As a result, there is a gap in time and space between the construction site and the office, which leads to low efficiency and lack and confusion of data.
Information technology (IT) plays an important role to control and manage construction projects success-fully, especially in enhancing communication and co-ordination among participants. Communication and coordination need to be maintained to support the shar-ing of resources and competencies in the network of a construction chain. Furthermore, integrating promis-ing information technologies such as personal digital assistants (PDA), bar code scanning, and data entry mechanisms, can be extremely useful for improving the effectiveness and convenience of information flow in construction supply chain systems. This article presents a novel system called the mobile-based construction sup-ply chain management (M-ConSCM) system to improve construction information acquisition on site and provide an information-sharing platform among all participants of the construction chain utilizing web technology and bar-code-enabled PDA.
1.1 Problem statements
The performance of project management and control can be improved by enabling each participant to share information with others. However, two important as-pects of information sharing are information acquisition and information communication. Information acquisi-tion problems in a construcacquisi-tion project follow from the fact that most of the data and information are gathered from the construction site, which is an extension of the construction chain. The effectiveness of information and data acquisition influences the flow of information be-tween the office and the construction site. However, on-site engineers usually use written documents, drawings, contracts, specifications, and shop drawings for job sites. As a result, a gap in time and space between the job site and office causes the duplex, lack and confusion of data and information. In other words, existing means of pro-cessing information and collecting data are not only time consuming and costly, but also reduce the performance of project management in information acquisition. Fur-thermore, construction contractors normally depend on interactions over the telephone or fax machine to com-municate with suppliers, subcontractors, and designers. Consequently, transactions are often lost or misunder-stood. Such means of communicating information
be-tween sites and offices, and among all participants, are ineffective and inconvenient.
1.2 Research objectives
A web portal is developed to solve the information com-munication problem. This portal is controlled by a gen-eral contractor and provides subcontractors and suppli-ers with real-time project-related information-sharing services, dynamically responding to the entire construc-tion supply chain network. In this article, a mobile construction supply chain management (M-ConSCM) system is developed to be efficient and cost effective, to improve practical communication among participants, and to increase flexibility in terms of project delivery and response times. The M-ConSCM system is a web-based system utilized to effectively integrate general contrac-tors, subcontraccontrac-tors, and suppliers, such that construc-tion merchandise is made and distributed in the right quantities, to the right locations, at the right times.
Paper-based documents are being superseded by inte-grating PDAs and bar code systems with the M-ConSCM system to solve the information acquisition problem. PDAs can extend M-ConSCM systems to construction sites. The efficiency of data collection can also be im-proved using automated bar-code-enabled PDAs to en-ter and edit data on the job site. By using web tech-nology and mobile devices, the M-ConSCM system for general contractors creates tremendous potential to in-crease the efficiency and effectiveness of information flow, thereby streamlining construction processes with other participants.
The on-site engineer often wastes time by traveling to obtain information when no other efficient means of communication is available. The portal and PDAs allow on-site engineers to update data from the con-struction site and then upload them immediately to the supply chain web portal; suppliers and subcontractors can receive real-time project-related information and make better decisions for the future management and control of the project. The system enables project man-agers to make the right decision in a “quick-response” environment.
This research develops a mobile supply chain control system for construction projects. The constituent objec-tives include (1) developing a framework for a mobile supply chain control system for construction contractors; (2) applying such a system that integrates bar codes with PDA technology to increase the efficiency of job site data collection; (3) developing a web-based portal for construction supply chain control providing real-time in-formation and wireless communication between offices and sites, subcontractors, and suppliers; (4) providing on-site engineers with updated information, accessed via the internal supply chain control system between the office and the job site; and (5) supporting project managers
Ineffectiveness and inconvenience data capture and collection on site
Data input rework
Easy to make mistakes in the information input process
No automated data capture service Construction Site
No real time site information/data update
Information is distributed to many different locations
Main Office
No Information Sharing Environment
No Dynamic Real-time Control Supply Chain Participants
Problem Statements Problem Solutions
Determine How to Transfer Data between Control Center and Site
Program & Implement Portal System
Link PDA To Portal
Test and Modified System Design Database for Portal System Determine Needed Data for Portal System Developing Portal to Centralize and Access the Project Information
Determine Which Information or Data to Information Sharing among Participants
Design and Determine Delivery Status for Development in the System
Link to Portal from Participant by Web
Test and Modified System Determine Information/Data to Monitor or
Information Sharing Improving Project Delivery via Information Sharing among Participants Study On-Site Needed Data for Use
Developing PDA-based Data Acquisition in Construction Site
Determine PDA Hardware
Determine Dataflow to PDA System
Program & Implement Mobile PDA System Design Database for PDA Determine Needed Data to enter PDA
Test and Modified System
Determine How to Transfer Data between PDA and Bar Code
Print the Bar Code and Stick Tape to Monitored Component Design Data Attribute for Bar Code
Test Connection between PDA and Bar Code Determine Hardware and Software for Bar
Code
Print the Bar Code and Stick Tape to Monitored Component
Integrating Bar Code with PDA to Capture Data automatically for Construction Activity
Fig. 1. Problem statement and problem solutions for construction information acquisition on site and information sharing
among participants.
of each partner to monitor and control the construction process dynamically. Figure 1 illustrates solutions used in the real case of a construction in Nankang Software Park in Taipei, by Century Development Corporation. With appropriate modifications, the M-ConSCM system can be utilized at any construction site for contractors or suppliers in support of the M-ConSCM system.
2 CONSTRUCTION SUPPLY CHAIN FRAMEWORK FOR GENERAL CONTRACTORS Supply chain management (SCM) is a concept that orig-inated and flourished in the manufacturing industry. The
first visible signs of SCM were in the Just-In-Time (JIT) delivery system, as part of the Toyota Production System (Shingo, 1988; Ruben and Lauri, 2000). The supply chain has been defined as “the network of organizations that are involved, through upstream and downstream link-ages, in the different processes and activities that pro-duce value in the form of products and services in the hands of the ultimate customer” (Christopher, 1998). SCM is the supply chain management of activity from raw material supply to consumer to minimize the time taken to perform each activity, eliminate waste, and of-fer an optimal response by maximizing value (Robert and Nichols, 1999). Tserng and Lin (2002) combine the
Owner Consultant Firm Supervisor Firm General Contractor Material Suppliers Equipment Suppliers Subcontractors Design Firm
Legend supply chain demand chain
Upstrea m D o w nstrea m
Fig. 2. Construction supply chain framework for the general contractor.
quick response mechanism of IT with portfolio theory in financial management to develop the Accelerated Sub-contracting and Procuring (ASAP) model for construc-tion supply chain management. An organizaconstruc-tion does more than merely managing its own portion of the supply chain. The process usually involves suppliers and users, as well as ancillary organizations.
Supply chain control (SCC) is one of the important parts of SCM. Supply chain control in construction usu-ally involves a group of companies and individuals work-ing collaboratively in a supply network of interrelated processes or activities designed most effectively to sat-isfy end-customer needs, while rewarding all members of the chain (Arbulu and Tommelein, 2000). Supply chain control in construction is recognized as improving the process of information flow, saving costs, and supporting revenue-enhancing business strategy.
Figure 2 presents an overview of the construction supply chain framework for the general contractor. The upstream supply chain for the general contractor includes superintendents, architects/designers, consul-tants, and the owner. The downstream supply chain in-cludes subcontractors, equipment suppliers, and material suppliers.
Usually, the construction supply chain includes an in-ternal supply chain and an exin-ternal supply chain (see Figure 3). From the general contractor’s perspective, the internal construction supply chain is the internal net-work among the head office, job-site office, and job site. Besides, the external construction supply chain is a big and complicated organization. With the assistance of In-ternet technology and applications, the internal network and external network can be chained together to
im-prove construction project information and communi-cation (Lin and Tserng, 2003a).
In the construction projects, most initial construction data come from the construction site. On-site engineers obtain data on the job site and bring it back to the office so that project managers can make the right decisions using his/her tools. Accordingly, the effective acquisition of accurate data from the job site plays an important role in governing the performance of the system.
Information sharing eliminates the need to regener-ate or reenter the same information in different offices. Eliminating multiple data entry also helps maintain data consistency and reduces human errors. For instance, the staff in the estimating department estimated the required quantity of cement in a project. With this information together with the project schedule, a purchasing officer can use the information and place an order. Tradition-ally, this information is reentered into various isolated systems such as scheduling and purchasing systems. With information sharing, the information is entered once and shared with other departments and partners.
The construction industry is one of the most com-plex industries because its products are unique and sev-eral participants are usually involved in the project. Participants change in every construction project. Con-sequently, developing a formalized SCM system for the construction industry is extremely difficult. However, IT critically enables effective supply chain control (Simchi-Levi et al., 2000), as is demonstrated by the ConSCM system, which uses various technologies to share and dis-tribute information.
Designing the framework of a construction SCM system in activity-based units is helpful, because
Suppliers Subcontractors Job Site Job Office Owner Design Firm Consultant Firm
Internal Supply Chain
External Supply Chain Suppliers Customers General Contractor Bar Code Head Office Internet Internet
Construction Supply Chain Control Portal System
Fig. 3. Framework of internal and external construction supply chain.
construction projects are normally distinguished and an-alyzed in activity units. Figure 4 presents a sample con-struction process, in which each activity of the project has manpower, equipment, and material supply components. The upper part in Figure 4 is expressed in the way of tradi-tional schedule controlling for the activity, the lower part is explained with the combination of supply, delivery, and traditional schedule controlling for the component sup-ply and delivery of each activity. The resulting combina-tion allows any project participants to trace and control their project more efficiently and progress while being fully integrated with the supply chain concept. The stock-pile following steel assembly means waiting status before steel assembling finishes and the stockpile for concrete placement means waiting status before concrete place-ment starts. The information sharing is the key to the success of a supply chain because it enables project par-ticipants to make decisions that cross both systems and companies (Sunil and Peter, 2001). A practical construc-tion SCM system can incorporate PDA, bar code, and portal technologies to empower participants in construc-tion projects. The rest of this secconstruc-tion discusses the use of PDAs, bar code systems, and portals in more detail. 2.1 Using PDAs on construction sites
Various kinds of mobile device have been adapted to field jobs on construction sites. Recently, the PDA rev-olution has come to the construction industry. The pop-ularity of PDAs is growing rapidly because more
pow-erful devices are being developed and a wider range of applications are becoming available. The main features of PDAs include: (1) access to calendar, address book, notes and to-do lists; (2) browsing the Internet or provid-ing web-clippprovid-ings; (3) Internet access either via modem, cell phone, or wireless access; (4) synchronizing data be-tween PDAs and desktop PCs; and (5) a platform for add-on software (McPherson, 2000; Johnson and Broida, 2000).
The benefits of using mobile devices in the construc-tion industries have been well documented (Baldwin et al., 1994; Fayek et al., 1998; McCulloch, 1997). Fur-thermore, mobile devices have been applied in many ar-eas in the construction industries, such as the following: (1) to provide wearable systems to support field inspec-tion (Sunkpho and Garrett, 2003); (2) to support pen-based computer data acquisition for construction survey records (Elzarka and Bell, 1997); (3) to support collab-orative and information-sharing platforms (Pena-Mora and Dwivedi, 2002), and (4) to utilize mobile comput-ers to access data capture for piling works (Ward et al., 2003).
In a construction project, engineers and workers need to be provided with the latest available information on the construction site. To understand the problems on construction sites and solving them with PDAs, a survey was conducted during a construction project of Nankang Software Park located in Taipei by Century De-velopment Corporation, to determine the information required by on-site engineers. Project managers, on-site
Earthmoving Truck Excavator Manpower Steel Assembling Form Work Place Concrete Concrete Manpower Manpower Steel Manpower Form :Stockpile
:Manpower Supplier :Equipment Supplier :Material Supplier
Legend
:Activity Name : Supply Relationship Earthmoving Steel Assembling Form Work Place Concrete Legend :Activity :Progress Flow
Supply Chain Concept Typical Construction Project Scheduling
Supply Chain Project Scheduling
Fig. 4. Construction supply delivery supporting illustration of an example.
engineers, and general engineers completed the survey: the response rate to the 20 questionnaires was 90% (18 responses). The survey was made to identify the do-main knowledge that relates to the problems on the con-struction site and to classify information required at the construction site. The result of the survey is summarized in Table 1 and Figure 5. Table 1 shows how PDAs can pro-vide support in situations that commonly arise on con-struction sites. Figure 5 shows the applications of PDAs on construction sites.
2.2 Applying bar code to construction
Bar code is an automatic identification solution that streamlines identification and data acquisition.
Further-more, bar code has been applied to many fields since the early 1960s, such as assembly checking, fixed asset inventory control, tracking, and records management. In the construction industry, Bell and McCulloch (1988) started a research project to explore the potential appli-cations and the resulting cost-saving benefits of bar code use in construction. Then, the application of bar code has been used in many areas in the construction industry, as follows: (1) to identify and find materials and build com-ponents on a construction job site (Bell and McCulloch, 1988; Bernold, 1990; Anderson, 1993; Skibniewski and Wooldrige, 1992; McCulloch and Lueprasert, 1994); (2) to automate yard control to reduce loss and misiden-tification of material and equipment (Lundberg and Beliveau, 1989); (3) to track and manage both small and
Table 1
Problems on construction sites and their solutions with PDAs
Function Current status Problem Solution with PDAs
Control
Inventory control Assist on-site engineers handle inventory
management on the site
Maintenance control Paper-based work Time-consuming and
ineffectively distributed
Assist on-site engineers handle asset maintenance management on the site
Schedule control Assist on-site engineers to handle schedule
control on the site
Quality control Assist on-site engineers to handle quality
control on the site Record
Experience record Provide on-site engineers a portal tool to
write down know-how tips on the site
Process record (voice) Inconvenient & not
handy
Inconvenient, no handy devices
Provide on-site engineers a portal tool to write down experience tips on the site
Process record (photo) Easy for on-site engineers to record
construction process
Process record (video) Easy for on-site engineers to record
construction process Communication
E-mail N/A N/A Provide on-site engineers to send and read
e-mail by PDA Reference
E-drawing Help on-site engineers refer to the
construction drawings directly from PDA
E-specification Paper-based work Dreadful,
inconvenient
Help on-site engineers refer to the specification directly from PDA
E-contract Help on-site engineers refer to the contract
directly from PDA
E-manual Help on-site engineers refer to the manual
directly from PDA
Web Search Web Search Drawings Drawings Manuals Manuals Digital Photo Digital Photo Scan Label Use PDA to collect data
accurately and rapidly
Use PDA to search Information or access Portal by Wireless Modem and Browser
Use PDA to record digital photos with accessories
Use PDA to refer and note construction drawings
Use PDA to refer digital manuals Contracts & Specification Contracts & Specification Checklist Checklist
Memos & Notes Digital Films Digital Films
GPS GPS
Use PDA to search GPS Information on the Portal by Wireless Modem and
Browser Use PDA to refer digital contracts and specification
Use PDA to edit memos and notes Use PDA to record digital
films with accessories
Use PDA to edit checklist
large equipment on the job site (Wirt et al., 1999); (4) to track job-site workers (Bell and McCulloch, 1988); (5) to support scheduling, resulting in better budgetary control and substantial cost savings (Blakey, 1990); (6) to identify documentation, drawings, material, equipment, and project activities (Stukhart and Cook, 1990; Rasdorf and Herbert, 1989; Finch et al., 1996); and (7) to integrate bar code and GIS for monitoring construction progress (Cheng and Chen, 2002).
Bar code technology can be used with PDAs to enable on-site engineers to integrate seamlessly work processes at job sites because of its accuracy and ability to cap-ture data effectively. With a bar code scanner plugged into a PDA, the bar-code-enabled PDA can be a power-ful portable data collection tool. Additionally, bar code readings increase the accuracy and speed of information communication, indirectly enhancing performance and productivity.
2.3 Using a portal in the construction supply chain Portals, a unique but occasionally complex concept troduced in the late 1990s, are web sites that collect in-formation related to specific themes or topics and pro-vide users with access to related services and information sources. Besides, a portal is an ideal platform for sharing information in a supply chain system. When a portal is used, all project-related information that is centralized in a project database can be obtained only through a web interface. The portal also provides authentication and access control mechanisms so that project partici-pants can access information according to user privileges and activity-related units. In practice, however, the ex-change of information among participants is not as easy as it seems. Several different systems and standards are used; the peer-to-peer relationships among companies in the network are normally too many to manage, and most systems do not support easy exchange of informa-tion with other systems. Furthermore, most participants are very reluctant to share information with other par-ticipants. A portal represents a solution to these prob-lems. Tserng and Lin (2003) develop an electronic ac-quisition model for project scheduling (e-AMPS) portal to automatically acquire external information and pro-vide participants with construction information sharing. An e-Hub construction supply chain management (Hub-ConSCM) system is developed for information sharing and analysis among project participants (Lin and Tserng, 2003b). Standardized interactions with one portal are easier to manage than are many peer-to-peer relation-ships. IT can help to solve the problems that plague several supply chains. Electronically exchanging infor-mation reduces the number of errors and increases the efficiency of the work processes. When one participant
can use the information of other participants in the sup-ply chain, the negative effects of uncertainty can be the-oretically eliminated. Figure 6 presents a framework in which all participants share updated information to their related activities via a web portal.
3 DEVELOPMENT OF THE M-ConSCM SYSTEM The internal construction supply chain management (ConSCM) system can be divided into three subsys-tems: the construction enterprise resource planning (ConERP) system, the construction supply chain man-agement center (ConSCMCenter) system, and the M-ConSCM system. The M-M-ConSCM system extends the ConSCM system from offices to job sites to assist with forecasting and analysis services, whereas the ConERP system mainly deals with data transactions in all de-partments or systems integration within a construction company.
Similar to project scheduling management, M-ConSCM, which is based on the concept of undertak-ing activities of project plannundertak-ing and control, is devel-oped to integrate M-ConSCM with the ConERP and ConSCMCenter systems. All data are stored and clas-sified by activity-based units in the M-ConSCM system. Also, the M-ConSCM services described in this work are made available to all the participants (suppliers and sub-contractors) of a project, through a specially designed portal, which also serves as a real-time and mail com-munication channel for projects. All the authorized par-ticipants can run their quality controls, schedule con-trols, and inventory-management work, based on the data shared through the portal service. When the data are updated on the server side, e-mails are automatically sent from the server to the general contractor’s project manager and participants involved in the relevant activ-ity. The following section presents a detailed treatment of the development of the M-ConSCM system.
3.1 System usage overview
The M-ConSCM system is comprised of three compo-nents: PDA, bar code, and portal. Notably, both the PDA and the bar code components are on the client side, whereas the portal component is on the server side (see Figure 7). Within the M-ConSCM system, all project-related information acquired by on-site engineers is cen-tralized in a supply chain system database (portal model database). Project participants (subcontractors and sup-pliers) in the supply chain may have access to all or some of this information through the portal, depending on their access privileges.
Fig. 6. Information sharing in the project scheduling using the portal.
3.2 System architecture
The server of the M-ConSCM system has three distinct types of layers—presentation, application, and database layers—each with its own responsibilities.
The presentation layer defines administration and end-user interfaces suited to the work of that end user. The users can access information through web browsers, including Microsoft Internet Explorer or Netscape Nav-igator. Administrators can control and manage informa-tion through the web browser as well as a separate server interface.
The application layer defines various applications for information collection and management. These applica-tions offer system security, information sharing, project control, project monitoring, and system administration functions. The database layer includes DB2 Everyplace, DB2 Universal, and SQL Server 2000. All the data are
stored and organized in DB2 Everyplace for mobile de-vices. The data uploaded from mobile devices (client) are stored in DB2 Universal Database as a medium between the server and the client. Finally, SQLServer 2000 pro-cesses and manages the M-ConSCM system database.
3.3 Modules of the M-ConSCM system
The M-ConSCM system is composed of a construction supply chain control portal integrated with mobile de-vices and bar code technology (bar-code-enabled PDA). The following is a brief description for each module. 3.3.1 Web portal module of M-ConSCM system— ConSCM portal. The ConSCM portal is an information hub in the M-ConSCM system for general contractors. The ConSCM portal enables all the participants to log
Production
Client Side
Inventory On-site
Inspection Delivery Construction
Check Refer Note
M-ConSCM
Server Side
Subcontractor Head Office On-site Engineer Manager Suppliers
Presentation layer
Application layer
Database layer Database Server
MS SQL Server 2000
JSP
Personal computer & Web browser (IE)
MS Windows 2000 Server Apache Server Client Application Server Components Java 2 SDK Backup Tier 1 Tier 2 Tier 3
Fig. 7. M-ConSCM system framework overview.
onto a single portal site and immediately obtain the in-formation they need to make their own plan. The portal is a simple presentation such as “Kanban” to both suppli-ers and subcontractors. It gives supplisuppli-ers information on the inventory levels of other portal users and allows them
to manufacture products accordingly. The GC can access diverse information and services via a single front end on the Internet. For instance, a supplier can log onto the por-tal, enter an assigned security password, and gain access to real-time information about the production schedule.
Fig. 8. Information delivery from the PDA. The general contractor can check on the production or
shipping status of an order, the availability of inventory, or a variety of other project-related data.
The ConSCM portal is based on Microsoft’s Windows 2000 operating system and Internet Information Server (IIS) as the web server. The prototype is developed us-ing Java Server Pages (JSP), which are easily incorpo-rated with HTML and JavaScript technologies, to trans-form an Internet browser into a user-friendly interface for users. Microsoft’s SQLServer 2000 is used as the database for storing all information. All e-specification and e-contracts saved in the server side must be stored in the e-book format for downloading into PDAs at the job site. The ConSCM portal provides a single person-alized gateway that enables all engineers on the Con-SCM system to access relevant information sent back from the PDAs. The ConSCM portal provides a solu-tion that involves a single, unified database, linked to all functional systems with different levels of access to in-formation, depending on the user’s role, both within an organization and across organizations and other supply chain participants.
3.3.2 Bar code module of M-ConSCM system. Two mo-bile device platforms, Palm OS and Windows CE, are se-lected as the bar-code-enabled PDA hardware systems. The M-ConSCM system uses Palm Scanner (Symbol SPT 1500) and iPAQ Scanner (Symbol SPS 3000). In the M-ConSCM system, bar code tags and labels are applied to the materials, equipment, and property, as well as to the item control list. All construction bar code applica-tions in the M-ConSCM system use the Code 39 symbol-ogy (Bell and McCulloch, 1988), and bar code labels are printed using high-quality laser printers.
Two types of bar code software are used in this sys-tem: bar code labeling software and bar code tracking software. Bar code labeling software provides the
func-tion for designing and printing quality labels. Bar code tracking software is applied to read and track the bar codes.
3.3.3 Mobile device (PDA) module of M-ConSCM system. As mentioned in the previous section, Palm OS and Windows CE are the two platforms used to operate the M-ConSCM system. Visual Basic and eMbedded Vi-sual Tools 3.0 are the programming language and tools used to develop the module. IBM DB2 Everyplace and Universal Database serve as the PDA database for the Palm OS-based PDA; SQLServer for CE serves as the PDA database for the Windows CE-based PDA. Addi-tionally, On-site Viewer (http://www.autodesk.com) for Windows CE is installed on the Windows CE-based PDA to allow viewing, marking up, and measuring AutoCAD drawings on the PDA.
In the PDA module, all the data files are first stored in the PDA database before being sent to the server through the Internet. After the application in the PDA is run, all the data files are sent, transformed, and saved in the server side database using open database connectivity (ODBC) and Java database connectivity (JDBC) technologies. Figure 8 shows information deliv-ery from PDA module and Figure 9 offers further detail of the conceptual semantic diagram of the PDA modules. Furthermore, Figure 10 presents an E-R diagram for the PDA module.
3.4 Analysis of the supply delivery process
To trace the supply delivery process, expected variance and actual variance expressed by set (1) and (2) are used, integrated with signal presentation in this system. The expected variance is calculated by the expected avail-able date from supplier-confirmed response for the ex-pected variance. The actual variance is calculated by the actual date from supplier-confirmed response for the
Fig. 9. Conceptual semantic diagram for the PDA module.
actual variance. Furthermore, a performance index called Supply Performance Index (SPI) is used for mea-suring the delivery performance. The SPI expressed by set (3) is calculated by dividing actual delivery duration by plan delivery duration. A negative variance and an index of 1.0 or smaller are favorable. If actual delivery duration exceeds plan deliver duration, more attention has been paid for the further project control.
Expected variance (EV)=
Expected arrival date− Plan arrival date (1) Actual variance (AV)=
Actual arrival date− Plan arrival date (2) Where Plan arrival date means the arrival or finish date for the delivering component; Expected arrival date in-dicates actual confirmed delivery data by the supplier; Actual arrival date implies actual delivery date.
Supply performance index= Actual delivery duration Plan delivery duration
(3) If expected arrival date is behind plan arrival date, it im-plies there is not sufficient time to supply or deliver to the job, and the delivery status is possibly behind sched-ule. If expected arrival date and plan arrival date are the same, the delivery status is possible on schedule. If expected arrival date is ahead of the plan arrival date, the delivery status is possibly ahead of schedule. Simi-larly, if actual arrival date is behind plan arrival date, it implies the delivery status is late already. If actual ar-rival date and plan arar-rival date are the same, the deliv-ery status is on schedule. If actual arrival date is ahead of plan arrival date, the delivery status is ahead of schedule. Table 2 summarizes these statuses and relates them to the variance and signal using in the system.
Table 2
The relationship between variance, status, and signals
Variance Status Signal
EV> 0 Delivery status is possibly behind schedule
Light red
EV= 0 Delivery status is possibly on
schedule
Light yellow EV< 0 Delivery status is possibly ahead
of schedule
Light blue AV> 0 Delivery status is already late Deep red
AV= 0 Delivery status is on schedule Deep yellow
AV< 0 Delivery status is ahead of schedule
Deep blue
To illustrate clear progress, there are eight statuses utilized in the system. They are production status, test status, storage status, delivery status, on-site status, in-ventory status, inspection status, and installation sta-tus. These progress statuses may be different from the projects. Engineers just select the proper progress status from the lists in the PDA or portal. When the current sta-tus is updated in the portal, the related participants of the activity can understand the newest situation of project progress. Furthermore, the system displays the status of delivery progress in the PDA and portal with different colors. For example, in the delivery process, the graphic feature displayed in deep red represents that the com-ponent has been behind schedule. Light red color shows that the component was delivered in the behind-schedule status, and deep blue color signifies that the component is in ahead-of-schedule status. As the installation of the component is completed and confirmed by the on-site engineers, the color of the associated graphic feature is changed to black.
Figure 11 presents an analysis flowchart of the sup-ply delivery status used in the M-ConSCM system. Also, Figures 12 and 13 present the transition of the supply status during the inventory and inspection status.
4 SYSTEM IMPLEMENTATION
This section illustrates the implementation and module of the bar-code-enabled PDAs system.
Daily Report Module: Daily Report module provides on-site engineers with an exhaustive record of daily activities on site. Engineers can record data regarding dates, weather, schedules, work done, situations that have arisen, and manpower, machines, and material in the inventory.
Inventory Management Module: Inventory Manage-ment module represents an easy-to-access and portable environment in which on-site engineers can trace and record all information on the status of materials in the warehouse or on the scheduled delivery list. The module enables on-site engineers to better manage inventory on construction sites.
Quality and Inspection Module: On-site engineers may download the most up-to-date tests of quality over the Internet. On-site engineers can enter the test result di-rectly in the PDA. Also, PDA displays the code and/or checklist for each important component and work. On-site engineers can also plot the position of unacceptable on a drawing and select related items from the lists in the PDA. The advantage of the module is that on-site engineers may enter/edit quality and inspection test re-sults on the construction site and all test records can
Start the Alarm Function
Identify the Item with Red Signal in Portal System
Notify Authorized Participants by E-mail Identify the Item with Red
Signal In the PDA
Identify the Item with Signal in Portal System
Enter Expected/Actual Arrival/Finish Date
Get Plan Arrived Date from System Scan Bar Coding Label
Calculate the AV value Deliver status is on
schedule
AV =0 Deliver status is ahead of
schedule
AV < 0
Deliver status is already late
AV > 0
Actual Delivery Day
Identify the Item with Deep Blue Signal In the PDA
Identify the Item with Deep Red Signal In the PDA
Identify the Item with Deep Yellow Signal In the PDA
Calculate the EV value
Deliver status is possibly behind schedule Deliver status is possibly
on schedule
EV =0
Identify the Item with Light Red Signal In the PDA
Deliver status is possibly ahead of schedule EV < 0
Identify the Item with Light Yellow Signal In the PDA
Identify the Item with Light Blue Signal In the PDA Expected or Actual Delivery Day Expected Delivery Day EV > 0
Fig. 11. An analysis flowchart of the supply delivery status used in the M-ConSCM system.
be communicated between the PDA and the portal via real-time synchronization, eliminating the need to enter repeatedly the same data.
Experience Tips Module: Experience Tips module pro-vides on-site engineers with a tool to record their notes, solutions, unsolved problems, and important thoughts on the construction site. On-site engineers enter the infor-mation into the PDA and send the inforinfor-mation back to the ConSCM portal directly, using the PDA’s wireless telecommunication capability. All unsolved problems and valuable experiences will be posted in the ConSCM
portal to augment the service of knowledge collection, sharing, and e-learning in the construction field.
Progress Monitor Module: This module has been built for managers and on-site engineers to monitor the progress of the important components. Furthermore, managers, on-site engineers, and project-related partic-ipants can share the current progress or delivery con-dition of these critical works and components. Sched-ule Management modSched-ule represents an easy-to-access and portable environment in which on-site engineers can trace and record all information on the status of
Check Delivery Quantity = Order Quantity
Set the supply status with green signal to In inventory
status
Identify the item with red signal in inventory status
Receive Notice is sent to supplier & GC by mail
No
Yes
Add the cumulative quantity for the item in the
inventory status Scan Bar Coding Label
Need to edit the command in
PDA?
The edited content/note is updated in the portal
directly
The notice of updated content is sent to authorized participants by
Yes
No
Identify the item with updated signal in inventory
status
Edit the command/note in the PDA
Fig. 12. Transition of the supply status during the inventory status.
components delivered in the warehouse or on the sched-uled delivery list.
E-Contract and E-Specification Module: This module gives on-site engineers the ability to download specifi-cations in advance and reference them, as if they were reading e-books on the job site during construction. It also has a “search” function that allows required infor-mation to be easily found and retrieved, saving time in the usually dynamic construction environment. On-site
engineers need not carry paper contracts and can even download these contracts in advance and reference them directly from their PDAs.
E-Drawing Module: The e-drawing module supported by AutoCAD provides on-site engineers with a conve-nient way to work on shop drawings without carrying paper drawings. On-site engineers can download these drawings in advance and reference them on the job site during construction.
item or component pass
inspection
Identify the item to move to next status as inventory
status
Identify the item with no pass signal in inspection status
No
Yes
Test item or component needed to inspect
Scan Bar Coding Label
Need to confirm by
supplier?
The content of result is updated in the portal
The notice of test result is sent to authorized member
by mail
Yes
No
Edit the test result in the PDA
Identify the item with red signal in inspection status
Fig. 13. Transition of the supply status during the inspection status.
5 CASE STUDY
A precast building project in Taiwan is selected to use as the basis for our case study. Full consideration of constructability in planning, design, and manufacturing phases to improve construction efficiency could
signifi-cantly affect the success of precast building construction (Tatum et al., 1987). Furthermore, selection of prefab-ricated structural components is a major critical activity in precast building construction projects. Therefore, an efficient controlling of scheduling and plan is able to sig-nificantly reduce the construction conflicts and project
delay. The structural components are prefabricated in the manufacturing plant and transported to the job site for installation. The schedules for prefabrication and transport of the structural components to the job site are developed based on the construction installation sched-ule. Also, the storage and management of the prefabri-cated components, installation sequence, schedule, and construction path planning should be well planned in advance.
In this case, the general contractor and the precast sup-plier try to use the M-ConSCM system to improve the project control ability. The precast component for the
Phase1: Production Status
Phase2&3: Test & Storage Status
Phase4: Delivery Status
Supply Side
Phase5&6: On-site & Inspection Status Phase8: Installation
Status
Phase7: Inventory Status
Demand Side
Input Flow Output Flow
Supply Manager M-ConSCM System On-Site Engineer Production Engineer Head Office GC Manager Subcontractor
Fig. 14. Process flowchart of illustration for M-ConSCM system.
building project is produced in the precast manufactory. In the precast supplier phase, the supplier discusses with the general contractor to determine which component will be tracing or monitoring in the beginning. When the component is determined for project control, the bar code label regarding the component is made and the related information is setup in the system. The main de-scription of the scenario (eight phases) is illustrated to explain the application of supply control using bar-code-enabled PDA and portals (see Figure 14). The system implementation flow diagram for the progress monitor is shown in Figure 15.
Item or Component Is Ready to be Produced
Is it Important or Necessary to
Track?
Determine the Tracing or Monitoring Information
No
Yes
Stick Bar Coding Label Make Bar Coding Label
Enter the Portal
Register Component for Tracing and Monitor
Select the Authorized Participants to Notice Setup the related Information to the system
Start Tracing and Monitor Scan Bar Coding Label
Select the Current Status
Whether This Phase Is last Phase?
Move the Next Phase Yes
No
Standby and Monitor Notify the Authorized Participants by E-mail
End of Tracing and Monitor Progress
Select the Current Status
Any Data or Information to
edit?
Enter Data or Result and Edit Description No
Yes
Update System Scan Bar Coding Label
Setup Phase Progress Phase
Fig. 15. The system implementation flow diagram in the progress monitor. 5.1 Production phase
In the precast supplier phase, the supplier will discuss which component will be tracing or monitoring in the beginning with the general contractor. After the com-ponent to be tracing and monitoring for project control is designed, it will be scanned with the bar code label to enter the information for the portal. Also, the gen-eral contractor can understand the updated production schedule in the portal directly.
5.2 Test and storage phase
In the test and storage phase, the precast manufac-tory produced the precast component and stored in
in-ventory before they are delivered to the construction site. The engineer in the supplier side uses the PDA to scan the precast component in the inventory and en-ters the data and attribute concerning the precast com-ponent. The data in the PDA synchronously updated the data/information to the portal, and the manager of the general contractor may understand that the precast component has already been produced, and is under the “Inventory” status.
5.3 Delivery phase
The staff will use bar-code-enabled PDA to scan the bar code label and select the status when the precast
Fig. 16. The application of PDAs used in on-site phase.
component is ready to be delivered to the construction site. The data in the PDA will synchronously update the portal, and notify the general contractor to update the status of the precast component for starting delivery. 5.4 On-site inspection phase
When this component has been delivered to the site, the on-site engineers scan the bar code label to update the
status (see Figure 16). PDA displays the basic informa-tion of the component and the checklist of each item. On-site engineers enter the result and edit the descrip-tion in the PDA and update the updated informadescrip-tion to the portal. In the meantime, the system will automati-cally alert the project manager in the head office to see the portal and check the updated information. Also, the supplier may check from the portal the amount of com-ponents delivered to the construction site.
Fig. 17. The application of PDAs used in the inventory phase.
5.5 Inventory phase
After the component is delivered in the construction site, the field engineer needs to check the component for quantity and quality, then enter the result in the PDA. Finally, the tracking process for the component will up-date the status to pass the test synchronously in the por-tal, and let the manager of the general contractor or the authorized suppliers check the process. Furthermore, the on-site engineer utilizes the web browser (IE6) on the
PDA directly to check the late-delivery items for in-ventory, according to the special day and project (see Figure 17).
5.6 Installation phase
Before the installation, the engineer checks the installa-tion locainstalla-tions and marks the problems in the PDA di-rectly (see Figure 18). The result/problem is updated in the M-ConSCM system portal. The project manager and
Fig. 18. The application of PDAs used in the installation phase.
subcontractor can understand the installation situation quickly and directly from the portal. When the compo-nent is ready to be installed after the testing and confir-mation process, its bar code label needs to be scanned again by the on-site engineer to update the information for the installation phase. Also, the information will be updated and announced synchronously in the portal. For the contractor and suppliers, they can gain information and understanding of real-time situations and advance a plan concerning their tasks.
6 CONCLUSIONS
This article presents a web-based portal system that in-corporates wireless technology and mobile devices to improve the efficiency and effectiveness of data acqui-sition on site and information sharing between partic-ipants to assist the managers to control and monitor the construction supply chain delivery progress. The M-ConSCM system not only improves the data acquisition on site efficiency by using automated bar-code-enabled
PDA, but also provides a monitor to control the construc-tion progress. On the client side, on-site engineers use PDAs to overcome time and space constraints, enabling them to read and record/edit all necessary or important information. On the server side, the M-ConSCM system offers a hub for the information and control center to provide suppliers and subcontractors real-time updated project-related information and to monitor the construc-tion progress. In the case study, the applicaconstruc-tion of the M-ConSCM system assists in improving operation progress monitoring for precast building construction (real-case application for office buildings in the Nankang Software Park of Taiwan, Taipei). The integration of real-time production and delivery information from precast sup-plier makes it easy for the GC manager to monitor and control the whole construction progress. Furthermore, the precast supplier may update the erection progress to reschedule the precast components production and assessment in real time. Real-time feedback regarding the status of progress on-site is provided to the fabri-cator off-site, so process steps can be resequenced op-portunistically. In comparison with the current meth-ods, all the information/data communication in the site can be improved by using automated bar-code-enabled PDAs and the information sharing among participants and is made quicker and more efficient through the por-tal technology.
7 SUGGESTIONS
Based on the findings of the case study, it appears that mobile devices are useful tools as they are related to the construction site operation progress. As the next step in the implementation process for further research, some suggestions are provided as follows:
1. It is very important to understand what information is needed to be shared among project participants because all content or information shared will dif-fer from project to project. Therefore, it is neces-sary for participants to have several meetings and discussions about information sharing before mod-ifying and developing the system.
2. The general contractor needs to take an active role in implementing the system on construction projects because most participants (suppliers) may be unable or unwilling to cover the additional costs involved due to their budget constraints.
3. Mobile devices should include durable functions for protection against physical shock, rain, moisture, and dust, if on-site engineers have to use them in construction sites.
4. Easy user interface by pen-touch is convenient and suitable for on-site construction engineers because
most of them may input data to the PDA with gloves on their hands.
5. Speed of operation and long-life batteries play an important role in the use of the mobile device in construction sites. Furthermore, the capability of a member card influences the use time when on-site engineers check drawings and pictures on the mo-bile device.
6. Bar code labels may be easily damaged during transportation, and items of construction are cum-bersome to scan for on-site engineers. Use of bar code labels handbook should be suggested for easy scan. This handbook contains all bar code labels for all kinds of the construction components/materials traced or monitored by the system.
ACKNOWLEDGMENT
The authors would like to acknowledge the National Science Council, Taiwan, for financially supporting this work under contract number NSC-90-2211-E-002-071. The authors would also like to thank the managers and engineers of Century Development Corporation for their assistance of this research project.
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