Site Management of Work-in-Process Buffers to Enhance Project Performance Using the Reliable Commitment Model: Case Study

Buffers have been commonly used as a production strategy to protect construction processes from the negative impact of variability. Construction practitioners and researchers have proposed several buffering approaches for different production situations and contexts. However, these solutions have been impractical for managing buffers. To overcome this, this study proposes a new site methodology for managing work-in-process (WIP) buffer in repetitive projects, on the basis of the reliable commitment model (RCM). RCM is a decision-making tool based on lean principles, which uses statistical models to develop more reliable work plans at the operational level. RCM helps to manage WIP buffer in work plans by using site information and planning reliability indicators that result in improved project performance, such as labor productivity and process progress. A repetitive building project was used as a case study. The main finding was that labor productivity, process progress, and waiting times improved when using larger WIP buffers than those typically used among crews. This shows the potential of RCM as a practical tool to manage WIP buffer sizes and to promote the use of lean production strategies at the operational level.     

Sequence Planning for Electrical Construction

The sequences in which work is completed bear significantly on the performance of electrical contractors in building construction projects. When project work sequences are poorly planned or poorly executed, electrician constructors often must contend with compressed schedules, trade stacking, and out-of-sequence work to ensure timely completion of a project. This paper analytically evaluates the importance of sequence planning to efficient electrical work. It describes changes that were made to crew-level planning procedures for an electrical contractor and the impact these had on crew performance. The analysis shows that sequence planning at both the project level and the crew level are important to the performance of electrical crews. Most notably, a strong correlation (0.73) was detected between crew planning performance one week and crew productivity performance in the following week. Results of the study are provided. Principles of sound sequences and guidelines for sequence planning are also captured from the analysis. These sequence guidelines are designed to avoid, where possible, the often adverse project conditions in which electrical contractors find themselves and to handle those conditions most effectively when they cannot be avoided.     

WorkPlan: Constraint-Based Database for Work Package Scheduling

A database program called WorkPlan has been created to systematically develop weekly work plans. Such work plans are used by crew foremen in scheduling work packages and allocating available labor and equipment resources. WorkPlan adopts the Last Planner methodology, which implements several lean construction techniques. A week prior to conducting work, WorkPlan guides the user step by step through the process of spelling out work packages, identifying constraints, checking constraint satisfaction, releasing work packages, and allocating resources; then at the end of the week, collecting field progress data and reasons for plan failure. This systematic approach helps the user create quality work plans and learn from understanding reasons for failure. The lean planning philosophy underlying WorkPlan and the functionality of the computer program implementation are detailed in this paper. Various ways of displaying work package data are illustrated. WorkPlan's job-shop scheduling view complements the view traditionally adopted by project management, as is reflected in scheduling tools using the critical-path method.     

Urban Freeway Bridge Reconstruction Planning: Case of Mockingbird Bridge

Urban freeway bridge reconstruction is a challenging process. Sites are often located in heavily populated areas and are always congested with traffic and construction activities. Lack of adequate planning on such projects can result in tremendous waste in project cost and schedule, traffic flow efficiency, and most importantly, safety to both the traveling public and construction crews. Accordingly, a need exists to develop techniques to help plan and construct urban bridge projects more effectively. This paper documents the process of replanning a bridge project, Mockingbird Bridge. The case describes a research effort that beneficially applied several construction engineering concepts to the project. For the project, the research resulted in sizable savings in cost and duration. For the industry, the case resulted in several lessons for future projects. Among these, the primary lesson is that the integration of bridge reconstruction sequence, constructability, and traffic control plans is crucial to project success.     

Effect of Preconstruction Planning Effort on Sheet Metal Project Performance

The complexity of construction industry requires the identification of work tasks and the coordination of interactions among them. As a result, construction planning is considered to be one of the most critical steps toward success and is the main focus of past research. Consequently, little research has been performed regarding the preconstruction planning, which is the planning completed by the contractor in the period between project award and project execution. This paper focuses on sheet metal preconstruction planning, primarily that of mechanical and heating ventilations and air conditioning contractors. The research was completed in three phases: phase one gathered data on the current state of preconstruction planning, phase two developed a model sheet metal preconstruction planning process to be used by sheet metal contractors, and phase three validated the model preconstruction planning process. Based on project data collected for this research, projects that used a planning process similar to the model process performed more successfully—they achieved an average profit margin of 23% while projects that were poorly planned experienced an average profit margin of ?3%.     

Optimal Planning and Scheduling for Repetitive Construction Projects

This paper presents a multiobjective optimization model for the planning and scheduling of repetitive construction projects. The model enables construction planners to generate and evaluate optimal construction plans that minimize project duration and maximize crew work continuity, simultaneously. The computations in the present model are organized in three major modules: scheduling, optimization, and ranking modules. First, the scheduling module uses a resource-driven scheduling algorithm to develop practical schedules for repetitive construction projects. Second, the optimization module utilizes multiobjective genetic algorithms to search for and identify feasible construction plans that establish optimal tradeoffs between project duration and crew work continuity. Third, the ranking module uses multiattribute utility theory to rank the generated plans in order to facilitate the selection and execution of the best overall plan for the project being considered. An application example is analyzed to illustrate the use of the model demonstrate its new capabilities in optimizing the planning and scheduling of repetitive construction projects.     

Selling with Integrity to Develop Your Engineering Practice

At times it can seem like a firm is relying on a few senior partners or executives to bring in work, which can be a burden to a senior partner and make a younger associate feel out of the loop. Getting everyone engaged in building the business can be accomplished by selling with integrity in a way that avoids the stereotypical image of the sales process and the salesman. Instead, the correct model for the engineer's involvement in sales is the physician. Engineers have special knowledge about what makes the built environment work and remedies for when something doesn't work. At a minimum, they are diagnosticians providing the data to the contractors or facility managers who will implement the treatment plans. As such, they have a responsibility to the "patient" (client) to ask the questions that will allow the patient to present symptoms leading to a diagnosis. But for the best results, they don't do it without a plan. Follow the author through the steps necessary for developing and applying an effective plan.     

Multiproject Planning and Resource Controls for Facility Management

Facility managers face the challenges of managing many different types of small, geographically dispersed construction projects. Depending on the complexity and distribution of projects, the time required to prepare for production consumes a large percentage of the total time required to complete the job. Increasing crews’ productive hours is a key objective when planning multiproject schedules. Existing methods, however, lack the effective means to explicitly model, analyze, and optimize resource utilization for these multiple concurrent projects. As a result, few facility managers fully exploit the potential to better manage their often limited budget and resources. This paper presents an explicit model of the mobilization requirements of multiple crews performing a variety of different activities over a geographic space. The model allows the facility manager to explicitly investigate the impact of crew composition, crew specialization, and depot locations. Using work rule decisions regarding alternative crew allocations, facility managers may dynamically allocate resources to optimize resources and to complete projects in a minimum amount of time. To verify and validate this new model, a computerized system, called FIRS (Facility/Infrastructure Resource Scheduler), was created to analyze the multiproject resource plans with data from two military organizations and a university campus. FIRS utilizes a new genetic algorithm that was developed specifically to work with multiproject scheduling. Using FIRS, facility managers can develop and test alternative crew allocations based on the qualifications of the crews available and the type of operation being performed.     

Decision Support System for Residential Land Development Site Selection Process

An important phase within the overall residential land development process is preliminary project planning, which is a highly coordinated effort involving a number of decisions that are made by a variety of individuals. One critical decision faced by the project owner and the development team, during the preliminary planning phase, is the initial selection of the most appropriate site for a proposed conceptual development plan. The scope of this paper deals with (1) formulating a model for the preliminary planning phase of residential site selection; and (2) developing an associated decision support system that can assist the decision makers during this phase of the project. The analytical hierarchy process was the decision making theory used in the site selection decision support system. Analytical hierarchy process uses a hierarchical structure comprising both quantitative and qualitative factors that are based on factual data and the knowledge and experience of the decision makers.     

Craft Jurisdiction Impact on Construction

Construction craft jurisdiction, normally exercised by unions, includes both territorial and technological claims to certain categories of work. Jurisdiction is important to unions in maintaining membership, negotiating wages and benefits, defining apprenticeship programs, and establishing work rules. This paper reports on a research project that had three main objectives: (1) Collect and analyze statistics on the incidence of jurisdictional disputes; (2) evaluate existing jurisdictional dispute settlement mechanisms; and (3) survey contractors and owners to determine the impact of craft jurisdictional practices (not only disputes) on costs and schedules. The paper concludes that there is inadequate statistical information at present to support informed decision‐making on jurisdictional problems. Most dispute settlement mechanisms are antiquated and ineffective, but there are good plans in some local areas. The survey revealed that there are serious cost and schedule impacts on construction projects from observing craft jurisdictional practices.     

Information Technology Planning Framework for Japanese General Contractors

Developments in information technology (IT) continue to have a significant impact on the architectural/engineering/construction (A/E/C) industry. However, the issue of whether A/E/C organizations are receiving adequate returns from their IT investments remains an important managerial concern. Recently, Pe?a-Mora, Vadhavkar, Perkins, and Weber introduced a strategic IT planning framework for construction projects that includes four steps: environmental scan, internal scrutiny, IT diffusion analysis, and IT investment modeling. It analyzes the external and internal IT conditions of a project/firm, identifies the diffusion phase of IT in the project/firm, and finally evaluates the effects of IT investments on the project/firm. Although this framework was originally intended to plan future IT investments, we assume that the framework can also be used to evaluate ongoing or past IT investments in projects/firms. Following this idea, this paper presents an application of the Pe?a-Mora et al. framework to an ongoing IT project in Kajima Corporation, one of the largest Japanese general contractors. Kajima is currently developing an IT system called LINCS (Linkage of Information for a New Construction System). This synthetic information network system has been designed to share building data among design and construction stages and streamline design/build activities. By using the framework proposed in this paper, we analyzed how LINCS is justified in terms of its strategic and operational value for Kajima and its construction projects.     

“Lean” Comparison Using Process Charts of Complex Seismic Retrofit Projects

This paper compares the delivery of two retrofit projects where seismic isolation bearings were installed. The comparison is retrospective. The design teams on these projects did not implement “lean” thinking to develop their approach, nevertheless, observed process differences are characterized using a “lean” process evaluation and optimization tool, and then gauged and rationalized from that perspective. Cross-functional process charts identify functional parties with interrelated material or information handoffs. They help to identify (un)necessary steps or complexity as measured by number of handoffs and interacting parties. Analysis of these charts shows that project value may stem from the owner integrating design development with product procurement and construction method selection. On one project, integration was made possible by structural engineers evaluating the impacts of product procurement on overall project performance, expert consultants providing construction process reviews, and experienced contractors participating in installation sequence development. This paper illustrates the value of developing a symbiotic relationship between designers and suppliers in a niche market. It stresses the need for work structuring early on in the delivery process, integrating process with product development, to improve project delivery.     

Computer Simulation Model: Construction Analysis for Pavement Rehabilitation Strategies

Most state highways in the United States were built during the 1960s and 1970s with an infrastructure investment of more than $1 trillion. They now exceed their 20?year design lives and are seriously deteriorated. The consequences are high maintenance and road user costs because of degraded road surfaces and construction work zone delays. Efficient planning of highway rehabilitation closures is critical. This paper presents a simulation model, Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS), which estimates the maximum amount of highway rehabilitation/reconstruction during various closure timeframes. The model balances project constraints such as scheduling interfaces, pavement materials and design, contractor logistics and resources, and traffic operations. It has been successfully used on several urban freeway rehabilitation projects with high traffic volume, including projects on I-10 and I-710. The CA4PRS helps agencies and contractors plan highway rehabilitation strategies by taking into account long-life pavement performance, construction productivity, traffic delay, and total cost.     

Structural Equation Model of Construction Contract Dispute Potential

This paper presents the results of a structural equation model (SEM) for describing and quantifying the fundamental factors that affect contract disputes between owners and contractors in the construction industry. Through this example, the potential impact of SEM analysis in construction engineering and management research is illustrated. The purpose of the specific model developed in this research is to explain how and why contract related construction problems occur. This study builds upon earlier work, which developed a disputes potential index, and the likelihood of construction disputes was modeled using logistic regression. In this earlier study, questionnaires were completed on 159 construction projects, which measured both qualitative and quantitative aspects of contract disputes, management ability, financial planning, risk allocation, and project scope definition for both owners and contractors. The SEM approach offers several advantages over the previously employed logistic regression methodology. The final set of structural equations provides insight into the interaction of the variables that was not apparent in the original logistic regression modeling methodology.     

Building Better: Technical Support for Construction

Increasing complexity of many constructed facilities and escalating demands for project performance are driving significant changes in design and construction. Increased project integration and technical support of construction operations provide a promising response to these demands. This paper identifies and describes nine critical activities to increase technical support for construction: integrate early planning; plan for regulatory compliance; consider construction methods and sequences in design; tailor and time technical information to users’ needs; provide materials to support effective construction; identify and provide construction-applied resources; create an environment for safe, productive, and high quality work; technically support efficient construction operations and completion; and transfer experience between projects. The paper’s relevance to industry practitioners includes multiple benefits of completing these activities for firms, projects, and professionals, along with the necessary steps to develop this capability and gain these benefits. Educators and researchers can use the activities to structure course topics related to technical fundamentals of construction and integration with design, along with future investigations of construction process knowledge.     

Optimizing Cash Flows for Linear Schedules Modeled with Singularity Functions by Simulated Annealing

The ability of construction contractors to plan and manage cash flow is critical for their economic success. The cumulative interaction of outflows (labor, materials, and equipment costs) and inflows (progress payments less retainage) creates a profile with a complex zigzag shape. This could only be modeled by simplification, e.g., as values tabulated at discrete times; averaged S-curves without peaks; or envelopes of all possible constellations. Neither is suited for a fully integrated model that dynamically links schedules with their cash flows for optimization. Therefore, singularity functions, whose components define ranges of behavior between cutoffs, are used to flexibly yet accurately model cash flow profiles and their various payment terms. The new approach augments construction project management toward an integrated planning model and is validated with an example from the literature. Optimization with a simulated annealing algorithm shifts activity positions in a randomized but directed search for maximizing profits.     

Quality-Based Contractor Rating Model for Qualification and Bidding Purposes

A quality contractor on every construction project would make project management simpler for Department of Transportation (DOT) project engineers and strategic planning more accurate for DOT executives. A qualification model that includes the quality of a contractor’s past work would be invaluable in assuring that each project had a quality contractor. Including the quality of past work in the bidding process would further help in this goal. Implementation of such a model for both its potential uses would require business process reengineering for the DOT in two important areas: qualification of contractors and contract award procedures. The research team has produced an innovative model, called the Quality-Based Performance Rating (QBPR) system. This model receives inputs from traditional subjective sources and integrates them with totally objective data input from the results of tests of the project’s materials and workmanship, then uses these inputs to produce a score for each project that is further used by the system to generate an index for each contractor reflecting that contractor’s quality of work over a specified time frame.     

露天矿分期开采及内部排土探究

本文基于对分期开采和内部排土技术原理及方法的简要介绍,阐释了开采规划与工艺方案的设计原则,并且探讨了针对具体露天矿的特点,如何基于数学分析模型进行分期开采与内部排土技术方案的优化,完成不同分期的开采与回填范围划定、运输道路规划以及采掘与内排台阶施工相关工艺参数的确定。     

Improving Planning Reliability and Project Performance Using the Reliable Commitment Model

Commitment planning reliability at an operational level is a key factor for improving project performance. In the last 15 years, the Last Planner System, a production planning and control system based on lean production principles, has improved commitment planning reliability in the construction industry. However, many construction decision makers continue to rely on their experience and intuition when planning their commitments, which hinders their reliability. The reliable commitment model (RCM) is proposed to improve commitment planning reliability at the operational level by using statistical models. RCM is an operational decision-making tool based on lean principles that supports short-term forecasting commitment planning using common-site information such as workers, buffers, and plans. RCM was tested in several case studies, demonstrating its production forecasting capabilities and its ability to help increase commitment planning reliability and improve project performance. RCM also supports workload and labor capacity matching decisions. RCM has the potential of becoming a useful production decision-making tool.     

Non-Unit-Based Planning and Scheduling of Repetitive Construction Projects

Repetitive scheduling methods are more effective than traditional critical path methods in the planning and scheduling of repetitive construction projects. Nevertheless, almost all the repetitive scheduling methods developed so far have been based on the premise that a repetitive project is comprised of many identical production units. In this research a non-unit-based algorithm for the planning and scheduling of repetitive projects is developed. Instead of repetitive production units, repetitive or similar activity groups are identified and employed for scheduling. The algorithm takes into consideration: (1) the logical relationship of activity groups in a repetitive project; (2) the usage of various resource crews in an activity group; (3) the maintaining of resource continuity; and (4) the time and cost for the routing of resource crews. A sample case study and a case study of a sewer system project are conducted to validate the algorithm, as well as to demonstrate its application. Results and findings are reported.