Tracking the Location of Materials on Construction Job Sites

Automated tracking of materials on construction projects has the potential to both improve project performance and enable effortless derivation of project performance indicators. This paper presents an approach by which materials tagged with radio frequency identification (RFID) tags can be automatically identified and tracked on construction sites, without adding to regular site operations. Essentially, this approach leverages automatic reading of tagged materials by field supervisors or materials handling equipment that are equipped with a RFID reader and a global positioning system receiver. To assess the technical feasibility of this approach, a mathematical model has been formulated such that the job site is represented as a grid and the location of materials within the grid is determined by combining proximity reads from a discrete range. Field experiments were conducted using an off-the-shelf RFID technology, and several metrics were developed to quantify the field performance and compare it with the theoretical positional accuracy derived from the discrete formulation.     

Conjoining MMAS to GA to Solve Construction Site Layout Planning Problem

An optimal construction site layout planning (CSLP) is vital for project management. It can reduce the transportation flows and thus the costs of a project. Genetic algorithm (GA) is the most used algorithm to solve site layout problems, but randomly generated initial population in GA will decrease solution quality. Max-min ant system (MMAS) can offer a better initial population than the randomly generated initial population at the beginning of GA. In this study, a modified GA (MMAS-GA) formed by conjoining MMAS to the step of initialization of GA is proposed to solve CSLP problems. In order to reveal the computational capability of MMAS-GA to solve CSLP problems, the results of MMAS-GA and traditional GA are compared by solving an equal-area CSLP problem. The results showed that the proposed MMAS-GA algorithm provided a better optimal solution under the objective function of minimizing the transportation flows between the site facilities. The proposed MMAS-GA algorithm could assist project managers and planners to design optimal construction site layout, and thus to reduce construction costs.     

Material Requirements Planning for a Manufactured Housing Facility

To design an efficient and effective inventory control system for the manufactured housing (MH) industry, it is necessary to accelerate the flow of information and products across the supply chain. To achieve this goal, the system needs three ingredients: generators of quick information flow, generators of quick material flow, and facilitators of both information flow and material flow. This paper proposes a material requirements planning (MRP) system that uses a database approach to manage the large amount of information involved in the material-requirements estimation process for the MH industry. A prototype MRP database and a Visual Basic interface have been developed by using information collected through the research. The proposed MRP system was tested using data provided by a manufactured housing facility to demonstrate its functionality and application to any MH facility. This proposed MRP system can be used to develop better planning strategies and to respond quickly to unexpected changes in demand for the MH industry.     

Internet-Based Geographical Information Systems System for E-Commerce Application in Construction Material Procurement

This study combines two luminous areas, geographical information systems (GIS) and E-commerce system, and applies the combined technology in the business of construction material trading. In the era of electronic business, trades can be accomplished without limitations on time and space. The statement is true in principle only, but in reality, any kind of business activity must involve transportation of goods from one place to another, and therefore, constrain in space is always in existence. GIS is capable to integrate, to manage, and to analyze information regarding to space (spatial information). This study investigates the roles of internet-based GIS in E-commence systems. It is identified that there is a great potential to use GIS in E-commerce system to provide better services in location-based queries, business area analysis, and transportation analysis. Accordingly, an E-commerce system for the business of construction material is developed. The implemented system is called construction materials exchange, this is currently operating for the over 2,000 buyers, 29,000 suppliers, and 1,000 agents, and the system mainly servers for the great China region. This paper presents the system from its conceptual business model, logical system design, to the system implementation.     

Electimize: New Evolutionary Algorithm for Optimization with Application in Construction Engineering

In nonlinear construction optimization problems, the capability of current optimization algorithms to find an optimal solution is usually limited by their inability to evaluate the effects of changing the value of each decision variable on reaching the optimal solution. This paper presents fundamental research aimed at developing a novel evolutionary optimization algorithm, named Electimize, that mimics the behavior of electrons flowing, through electric circuit branches with the least electric resistance. In the proposed algorithm, solutions are represented by electric wires and are evaluated on two levels: a global level, using the objective function, and a local level, evaluating the potential of each generated value for every decision variable. The paper presents (1) the research philosophy and scope, (2) the research methodology, and (3) the development of the algorithm. The proposed algorithm has been validated and applied successfully to an NP-hard cash flow optimization problem. The algorithm was able to find a better optimal solution and identified ten alternative optimal solutions for the same problem. This should prove useful in enhancing the optimization of complex large-scale problems.     

Developing a Resource Supply Chain Planning System for Construction Projects

The high variability of construction environments results in high construction-cost variation, especially in material costs. Inadequate planning may cause material shortages that delay the project schedule or, alternatively, a substantial increase in inventory costs by producing or supplying materials earlier than they are needed at the construction site. In order to solve these problems, this paper studies steel rebar production and supply operations and establishes an optimal model that minimizes the integrated inventory cost of the supply chain. Based on the optimal model, this paper develops a decision-support system to generate a production and supply plan for a supplier and buyers of steel rebar. After utilizing the decision-support system to create the supply and production plan, this paper analyzes the results to study the influence of transaction constraints on inventory cost. This paper also discusses cases of global optimization of the inventory cost for the entire supply chain and compares them with cases of local optimization for individual members.     

Optimizing Resource Leveling in Construction Projects

Construction schedules, generated by network scheduling techniques, often cause undesirable resource fluctuations that are impractical, inefficient, and costly to implement on construction sites. This paper presents the development of two innovative resource leveling metrics to directly measure and minimize the negative impact of resource fluctuations on construction productivity and cost. The first metric quantifies the total amount of resources that need to be temporarily released during low demand periods and rehired at a later stage during high demand periods. The second measures the total number of idle and nonproductive resource days that are caused by undesirable resource fluctuations. The two new metrics are incorporated in a robust and practical optimization model that is capable of generating optimal and practical schedules that maximize the efficiency of resource utilization. An application example is analyzed to illustrate the use of the model and demonstrate its capabilities. The results of this analysis show that the present model and metrics are capable of outperforming existing metrics and eliminating undesirable resource fluctuations and resource idle time.     

Construction Project Scheduling with Time, Cost, and Material Restrictions Using Fuzzy Mathematical Models and Critical Path Method

This article evaluates the viability of using fuzzy mathematical models for determining construction schedules and for evaluating the contingencies created by schedule compression and delays due to unforeseen material shortages. Networks were analyzed using three methods: manual critical path method scheduling calculations, Primavera Project Management software (P5), and mathematical models using the Optimization Programming Language software. Fuzzy mathematical models that allow the multiobjective optimization of project schedules considering constraints such as time, cost, and unexpected materials shortages were used to verify commonly used methodologies for finding the minimum completion time for projects. The research also used a heuristic procedure for material allocation and sensitivity analysis to test five cases of material shortage, which increase the cost of construction and delay the completion time of projects. From the results obtained during the research investigation, it was determined that it is not just whether there is a shortage of a material but rather the way materials are allocated to different activities that affect project durations. It is important to give higher priority to activities that have minimum float values, instead of merely allocating materials to activities that are immediately ready to start.     

Development and Application of the Specialist Task Organization Procurement Approach

The study focuses on the development of an innovative procurement method in order to improve owners’ contracting strategies. The aim of this paper is to develop a procurement system that improves the overall project implementation process, in order to meet the project objectives of time, cost, and quality. The Specialist Task Organization (STO) approach is suggested based on a constructive research approach, where extensive theoretical development of the STO concept is developed. The analogical validation was carried out through the review of four case study examples in order to find the analogies between the positive outcomes of four case studies and the elements of the STO route. The proposed task-oriented approach utilizes integrated product (task) development, integrated management, and fragmented execution via task organizations. The merits of the STO approach include, the shifting of competition from only single design and cost based to multiple designs, life-cycle costs, alternative materials, and maintainability implications. The STO approach assumes a modular approach to design, and allows experts knowledge in design and construction through their involvement from preconstruction through project starts up. The suggested STO route is a potential tool in realizing complete sustainability in construction in terms of environmental and social sustainability, as well as economic sustainability.     

Time-Profit Trade-Off Analysis for Construction Projects

This paper presents a multiobjective optimization model that provides new and unique capabilities including generating and evaluating optimal/near-optimal construction resource utilization and scheduling plans that simultaneously minimize the time and maximize the profit of construction projects. The computations in the present model are organized in three major modules: (1) a scheduling module that develops practical schedules for construction projects; (2) a profit module that computes the project profit; and (3) a multiobjective module that searches for and identifies optimal/near optimal trade-offs between project time and profit. A large-scale construction project is analyzed to illustrate the use of the model and to demonstrate its capabilities in generating and visualizing optimal trade-offs between construction time and profit.     

企业自行采购物资的计划与管理

介绍了矿山企业自行采购物资的计划与采购管理,重点述说了计划的分类、编制的原则和方法,详细说明了招标采购、比质比价采购、代储代销、单耗承包等采购方式及策略的运用。     

Parallel Computing Framework for Optimizing Construction Planning in Large-Scale Projects

Available construction optimization models can be used to generate optimal tradeoffs between construction time and cost, however their application in optimizing large-scale projects is limited due to their extensive and impractical computational time requirements. This paper presents the development of a parallel computing framework in order to circumvent this limitation. The framework incorporates a multi-objective genetic algorithm module that identifies optimal trade-offs between construction time and cost; and a parallel computing module that distributes genetic algorithm computations over a network of processors. The performance of the framework is evaluated using 150 experiments that represent various combinations of project sizes and numbers of processors. The results of this analysis illustrate the robust capabilities of the developed parallel computing framework in terms of its efficiency in reducing the computational time requirements for large-scale construction optimization problems, and its effectiveness in obtaining high quality solutions identical to those generated by a single processor.     

Agent-Based Construction Supply Chain Simulator (CS2) for Measuring the Value of Real-Time Information Sharing in Construction

This paper presents an agent-based construction supply chain simulator (CS2) that leverages computer agents technology for modeling a virtual construction supply chain. Although construction managers and contractors do not consciously consider a supply chain and its management, they all interact with the members of a supply chain and make related decisions. Having real-time information available at any time can increase information transparency, which in turn makes it easier for project managers to identify potential risks. CS2 is a modified version of the beer game that has been widely used for illustrating the importance of real-time information in the manufacturing process. Two different types of simulations are presented in this paper, namely human-to-human and computer-to-human interactive simulation. In the simulations, a group of people play different roles, as does the current practice in construction. Results of this simulation test and verify the significance of real-time information sharing in construction. In addition, how the quantity of information affects the value of real-time information using the concept of illusion in cognitive science is investigated. The developed CS2 can be further used for educational purposes as well as for addressing the valuable lesson of real-time information sharing to practitioners.     

Particle Swarm Optimization for Construction Site Unequal-Area Layout

Layout of temporary facilities on a construction site is essential to enhancing productivity and safety, and is a complex issue due to the unique nature of construction. This paper proposes a particle swarm optimization (PSO)-based methodology to solve the construction site unequal-area facility layout problem. A priority-based particle representation of the candidate solutions to the layout problem is proposed. The particle-represented solution in terms of priorities should be transformed to the specific layout plan with consideration of nonoverlap and geometric constraints. In addition, a modified solution space boundary handling approach is proposed for controlling particle updating with regard to the priority value range. Computational experiments are carried out to justify the efficiency of the proposed method and investigate its underlying performances. This study aims at providing an alternative and effective means for solving the construction site unequal-area layout problem by utilizing the PSO algorithm.     

Theft and Vandalism on Construction Sites

Theft and vandalism on construction sites in the commercial construction industry is a problem that can affect productivity and drain profits. To explore the impact of theft and vandalism in the commercial construction industry, a survey was sent to commercial construction firms to gather information by which the magnitude of the problem of theft and vandalism could be estimated; and to determine what techniques have been successfully used to deter thieves and vandals. The responses were analyzed and several conclusions were developed. Firms engaging in all types of projects are susceptible to theft and vandalism. Theft is more costly to large sized firms ($100 million and over in annual volume of construction work) than smaller firms, but vandalism is more costly for smaller firms. This occurs despite the fact that larger firms use a greater number of measures to combat theft and vandalism on their construction sites. The results should be of particular interest to construction firms that want to reduce the number of theft and vandalism incidents.     

Parallel Genetic Algorithms for Optimizing Resource Utilization in Large-Scale Construction Projects

This paper presents the development of a parallel multiobjective genetic algorithm framework to enable an efficient and effective optimization of resource utilization in large-scale construction projects. The framework incorporates a multiobjective optimization module, a global parallel genetic algorithm module, a coarse-grained parallel genetic algorithm module, and a performance evaluation module. The framework is implemented on a cluster of 50 parallel processors and its performance was evaluated using 183 experiments that tested various combinations of construction project sizes, numbers of parallel processors and genetic algorithm setups. The results of these experiments illustrate the new and unique capabilities of the developed parallel genetic algorithm framework in: (1) Enabling an efficient and effective optimization of large-scale construction projects; (2) achieving significant computational time savings by distributing the genetic algorithm computations over a cluster of parallel processors; and (3) requiring a limited and feasible number of parallel processors/computers that can be readily available in construction engineering and management offices.     

New Mathematical Optimization Model for Construction Site Layout

Layout of temporary construction facilities (objects) is an important activity during the planning process of construction projects. The construction area layout is a complex problem whose solution requires the use of analytical models. Existing popular models employ genetic algorithms that have proven to be useful tools in generating near optimal site layouts. This paper presents an alternative approach based on mathematical optimization that offers several important features and generates a global optimal solution. The construction area consists of an unavailable area that includes existing facilities (sites) and available area in which the objects can be located. The available area is divided into regions that are formulated using binary variables. The locations of the objects are determined by optimizing an objective function subject to a variety of physical and functional constraints. The objective function minimizes the total weighted distance between the objects and the sites as well as among the objects (if desired). The distance can be expressed as Euclidean or Manhattan distance. Constraints that ensure objects do not overlap are developed. The new approach, which considers a continuous space in locating the objects simultaneously, offers such capabilities as accommodating object adjacency constraints, facility proximity constraints, object–region constraints, flexible orientation of objects, visibility constraints, and nonrectangular objects, regions, and construction areas. Application of the model is illustrated using two examples involving single and multiple objects. The proposed model is efficient and easy to apply, and as such should be of interest to construction engineers and practitioners.     

Relationship between Changes in Material Technology and Construction Productivity

There have been substantial changes in both material technology and construction productivity over the past several decades. By analyzing the changes in both material technology and productivity among 100 construction activities from 1977 to 2004, this research examines the strength and types of relationships that exist within these two occurrences. Through analysis of variance (ANOVA) and regression analyses, the researchers found that activities experiencing significant changes in material technology have also experienced substantially greater long-term improvements in both their labor and partial factor productivity. The research did find that a stronger relationship exists between changes in material technology and partial factor productivity than in labor productivity. The research also found that changes in the unit weight of materials had a significant relationship to labor productivity, while changes in installation and modularity had a significant relationship to partial factor productivity. The research findings will help industry practitioners to better understand how they may leverage technology to improve construction productivity, while also helping researchers understand the theoretical relationships between technology and construction productivity.     

Procurement of Design-Build Services: Two-Phase Selection for Highway Projects

In the United States, public agencies are adopting the design-build (DB) delivery method for delivering highway projects after having used the traditional design-bid-build method for generations. In the 2002 design-build contracting final rule, the Federal Highway Administration (FHWA) strongly encourages the use of two-phase selection procedures for DB procurement. This paper takes a case study approach to investigating the use of a two-phase process for selecting providers of highway design-build services. Using two DB projects in central Texas as case studies, the writers have analyzed project documentation and performed interviews with 37 project participants involved in procurement, including owner representatives and legal consultants. For the first case, the writers selected the $1.3 billion SH-130 tolled expressway project in central Texas. Procurement of the SH-130 DB contract was performed before the FHWA rule on DB contracting was released. In addition, the writers examined procurement activities for the $154 million DB contract for the SH-45 SE tolled expressway, which was procured by the same owner in 2004 following procedures identified in the FHWA rule. As a result, a process was developed that included activities to be performed between the delivery method decision and the contract execution. This process model tracks the differences between the SH-130 and the SH-45 SE processes that are attributable to the latter’s adoption of the FHWA Rule.