Impacts of Constructability Improvement

An analysis of the construction resource utilization tradeoffs, which occur from constructability improvements, provides insight into the constructability improvement process. Matrices of construction and engineering impacts likely to result from constructability improvements are presented. Constructability improvements collected on a large industrial construction project are analyzed for their impact to the job. Frequencies of occurrence of both desirable and undesirable impacts are noted, as are the cost‐significances of the various impact types. Constructability strategies and methods for achieving the most cost‐beneficial impacts are presented. Numerous findings are presented, such as the following: (1) The likelihood of delays may be decreased most effectively by increasing engineering information availability and understandability; (2) the amount of required construction manpower may be most effectively decreased by simplifying the design, combining design elements, and seeking optimal design‐originated construction techniques such as optimal construction systems, modularization, and improved design details. Of course, additional engineering effort may be required; and (3) construction activity durations may also be most effectively decreased by seeking optimal design‐originated construction techniques.     

Collecting Constructability Improvement Ideas

Project constructability improvement data collection techniques including voluntary survey, questionnaires, interviews, preconstruction meeting notes, and final project reports are discussed and analyzed in detail. Constructability data collected on a large refinery expansion project solicited with various collection techniques from various project personnel are presented. Considering six major types of constructability improvements, from both quantitative and qualitative points of view, two primary questions are addressed: (1) Which data collection methods are best in soliciting certain types of data; and (2) which source types are the most effective contributors in soliciting certain types of data? Numerous recommendations for effectively collecting constructability improvement data are presented.     

Industrial Project Constructability Improvement

Constructability is defined as the ability of project conditions to enable the optimal utilization of construction resources. Constructability improvements may heighten the construction‐sensitivity of designs, render the communication of engineering information as more effective, optimize construction‐originated construction techniques, increase the effectiveness of construction management policies, improve vendor∕subcontractor services, or identify needs for designer‐constructor communication during the project. Constructability improvement ideas collected on a large refinery expansion project are analyzed for content, and classification frequencies are observed. Analysis of engineering rework exposes the causes and costs of rework that occurs as a result of constructability problems.     

Organizing Constructability Knowledge for Design

Construction contractors have significant constructability expertise to contribute to the design process of projects. To utilize this expertise most effectively, the right information must be made available to the design team at the proper point in time and at the appropriate level of detail. Current methods for utilizing construction knowledge in design have made significant advances to improving projects. However, they are typically rudimentary: unstructured, not very efficient, and rely heavily on reviews. Organizing constructability information according to its use in the design process will allow project teams to take the best advantage of the construction expertise. This paper introduces a model for organizing constructability information based on timing and levels of detail. The model differs from current approaches because of this focus. How the model was developed is described. It is tested on six case study projects to assess applicability on different projects. An illustrative example is provided using a detailed case study of the Pentagon renovation project to show how the model can be used as a metric to guide constructability input during design.     

Constructability State of Practice Report

This report reviews guidance on constructability programs from a variety of sources and presents the current practice of constructability. The advice of several organizations and researchers is summarized to describe expectations for ideal constructability. Actual current constructability practice, based on results and analysis of a Constructability State of Practice survey, is described. Approximately 100 owners, architects, engineers, consultants, contractors, and construction managers answered the survey’s ten questions and provided written comments. The results provide a picture of current constructability practices in the architecture, engineering, and construction (AEC) industry and progress in recent years. Major conclusions include: (1) constructability has gained acceptance throughout the industry; (2) constructability efforts are clearly beginning in early project phases; (3) a wide variety of constructability techniques and new technologies are being implemented; and (4) obstacles to improving constructability remain, but may be changing. Finally, recommendations are provided based on areas where constructability practice can still be improved. This report is relevant to both industry practitioners and researchers.     

Incorporating Maintainability in Constructability Review Process

Life cycle cost or total cost analysis of a facility begins with the initial design concept and ends with the decommissioning of the facility. Decisions made during the design and construction phases routinely consider only the construction costs when analyzing the constructability of the project. Often the impacts of such decisions on the maintenance requirements for the facility are not fully appreciated and are therefore not formally addressed. The concept of “maintainability” addresses this concern and is a logical extension of the constructability concept. As such, maintainability may be incorporated as a part of the formal constructability review process (CRP). This article describes a model format for incorporating the best practices for maintainability into the CRP. The added life cycle value of incorporating maintainability into the CRP can only be assessed by analysis of accurate and complete maintenance cost data. Insights from such an analysis may facilitate more accurate estimates of the total costs of facilities.     

Assessing State Transportation Agency Constructability Implementation

Although guidance is available for state transportation agencies to establish constructability review processes (CRPs), nationwide implementation has been slow due, in part, to a lack of clarity regarding related costs and benefits and a perception that CRPs are resource intensive. This study funded by the National Cooperative Highway Research Program reveals that while numerous states have attempted implementation in various forms, obstacles have frequently either hindered or halted progress. Four elements appear to be essential for the successful implementation and continuance of a CRP: (1) institutionalization of the CRP Champion, (2) an emphasis on a quality-driven as opposed to a schedule-driven design process, (3) clear yet flexible guidelines for executing constructability reviews across the broad range of project types and sizes, and (4) a vehicle for meaningful expert input from construction contracting professionals. A benefit-cost model, founded on the proposition that CRP implementation provides efficiencies that result in significant cost and schedule reductions, is demonstrated using case studies. A need for more precise identification of costs and quantification of benefits is noted.     

Constructability Analysis in the Design Firm

The timely execution of a construction project is very important to the owner, who makes plans and commitments on the basis of the project’s anticipated completion date. Failure of design professionals to consider how a builder will implement the design can result in scheduling problems, delays, and disputes during the construction process. Constructability of design is a subjective scale that depends basically on a number of interdependent project-related factors. Many design firms have a formal (explicit) constructability program that is launched as early as the conceptual planning stage of the project. This research examines design professionals’ efforts to pursue constructability and provides recommendations for performing constructability reviews in an efficient and effective manner.     

Constructability Practices to Manage Sustainable Building Knowledge

Construction professionals have knowledge and competencies that can help improve the design and delivery of sustainable buildings. The introduction of construction knowledge during design using constructability practices has been shown to improve design and project performance. From a process perspective, this paper examines specific constructability techniques that can help manage sustainable building knowledge throughout the design process. Through scientific research, four constructability practices employed at the Pentagon renovation are assessed for their capability at managing sustainability input from contractors. The four practices are: (1) the use of an integrated organizational team to champion the effort; (2) physical and computer building models (mock-ups); (3) on-board reviews; and (4) lessons learned workshops. Twenty-one specific principles are then identified to provide further guidance to industry practitioners. These practices and principles pinpoint methods to help manage sustainable building knowledge, especially that made available by construction professionals during design and construction.     

Constructability Practices among Construction Contractors in Indonesia

The concept of constructability in the United States or buildability in the United Kingdom emerged in the late 1970s, which evolved from studies into how improvement can be achieved to increase cost efficiency and quality in the construction industry. It is an approach that links the design and construction processes. The studies in the Unites States, United Kingdom, and Australia have demonstrated that improved constructability has lead to significant savings in both cost and time required for completing construction projects. However, in implementing constructability improvement, it is important to consider the uniqueness of the construction industry in a specific country. This paper presents the study performed on the construction contractors in Indonesia with regard to their current constructability practices and its impact on the project performance. The study shows that many contractors in Indonesia have been implementing part of the constructability concept in their projects. The concepts that usually applied during the construction stage as part of the overall construction plan were planning the sequence of field tasks and analyzing layout, access, and temporary facilities     

Constructability Test for Cold In-Place Asphalt Recycling

Unstable subgrades are a major constructability problem for cold in-place asphalt recycling. The recycling operation is often performed by a train of equipment that mills, screens, crushes, and mixes the recycled material. This train is supported by the remaining pavement after the top has been milled off for recycling. Because the remaining pavement may be as little as 1 or 2 in. thick, good subgrade stability is required to support the train. A test is developed to assess subgrade stability using a dynamic cone penetrometer. The testing instrument is inexpensive and portable, and the initial testing program can be carried out for a typical project in 1 or 2 days. Guidelines are developed using data from a project that developed varying levels of subgrade instability during construction. The guidelines were corroborated by testing on other projects. The test may be used on projects having glacial till derived soil subgrades and in which equipment is supported by 1 or 2 in. of remaining pavement plus a soil-aggregate base. Additional research is recommended to develop test guidelines for different types of soils and different base support conditions.     

Constructability Improvement of Bridges Using Stepping Formwork

Many construction systems have been used to build several highway bridges and elevated roads in Egypt. Recently, the stepping shuttering system has been used in Egypt for cast-in-place concrete bridge. This system is most appropriate for concrete bridges of moderate spans ranging from 40 to 70 m. The stepping shuttering system provides appropriate means to satisfy local needs for concrete bridge construction in an urban environment, practically without infringing on traffic or property below. This paper presents an innovative method of construction that has been used in Egypt for the first time to build the 6th October Bridge extension. Issues regarding the constructability and innovation are highlighted, and the significant aspects during the bridge construction are documented. Also, the difficulties encountered and the lessons learned are thoroughly investigated. In addition, evaluation of the system is discussed in terms of construction cost, schedule, and flexibility. Finally, this paper presents an innovative method that offers substantial opportunity for enhancing constructability of concrete bridges using the stepping shuttering system.     

Assessment of Constructability Practices among General Contractors

Modern construction has been characterized as a complex and fragmented process. These characteristics have produced a decrease in the quality and cost efficiency of projects. It has been proven that this problem can be partially overcome by implementing constructability, which is based on the integration of construction knowledge into design (as was done in the past). The implementation of constructability is not easy because it represents a change in the way things have been done in the last century. Prior research has found a lack of constructability efforts among participants in the construction industry, especially general contractors. Because builders can play an important role in implementing constructability, this paper assesses constructability practices among general contractors. The data were obtained from a mailed survey. It was found that contractors applied constructability concepts and participated during the earliest phase of the projects more often than is thought. In addition, the findings showed that constructability practices differed depending on the characteristics of the organization, the type of work performed, and the type of contractual arrangement.     

Modeling of Functional Construction Requirements for Constructability Analysis

Evaluating construction requirements should be an indispensable part of improving the constructability of a facility project. However, a number of existing function analysis approaches focus mainly on the final functions with respect to the finished facility. The construction industry still lacks methodologies to represent and evaluate the functional construction requirements for constructability analysis. This paper develops the concept of intermediate functions for representing the construction requirements from three perspectives, namely, function user, function provider, and the temporal and spatial relationships between the user and the provider. This is followed by the development of an in-progress product model to abstract the construction lifecycle of a facility product utilizing the concept of component state. Furthermore, the reference relationships among such perspectives as in-progress product, intermediate function, resource, and process are addressed. Based on these reference relationships, the bottleneck states for providing the intermediate functions can be detected. A case study of constructing the deck of a bridge using the balanced cantilever approach is presented to illustrate the utilization of this concept and representation.     

Tolerance and Constructability of Soldier Piles in Slurry Walls

Process capability (PC) characterizes the variation in a parameter of a process’s output. From a constructability perspective, investigating PCs for geometric variation is important when specifying tolerances for all construction processes. This paper investigates a case involving soldier piles used in a slurry wall and compares the design specified tolerances to as-built field data. As with other cases investigated by the writers covering many major construction processes, this case also shows that designers specify tolerances based on tacit estimates of variation limits, not PCs. Consequently, the PCs consistently exceed the design specified tolerances, preventing the possibility of proper tolerance management and causing problems to manifest during construction. The writers conclude that variation estimates are an inaccurate basis for specifying tolerances and instead should be based on PCs.     

Constructability Concepts in Kuala Selangor Cable-Stayed Bridge in Malaysia

The writers formulated a case study of the Kuala Selangor Cable Stayed Bridge to examine the application of the constructability concepts particularly during the conceptual planning and the design phases of the project. This paper presents the advantages of implementing the constructability concepts and the barriers that were encountered when applying these concepts during the planning and design phases of the cable stayed bridge project of Kuala Selangor in Malaysia. The writers concluded that barriers to constructability implementation that are related to the owner were the major impediments in the application of constructability concepts during the early conceptual planning phase. The opinion of the engineer was another factor behind nonapplication of some other concepts. At the same time, many others were implemented due to the awareness and opinion of the engineer and his ability to control their application.