Journal of Construction Engineering and Management

The National Cooperative Highway Research Program initiated a research project to develop a constructability review process (CRP) for transportation facilities. The basic objective of this research was to develop a systematic approach and methodology for constructability reviews. This paper describes the development of a CRP that meets the National Cooperative Highway Research Program's research objectives. A process approach is followed to integrate constructability improvements into project development for transportation projects. A function modeling tool is used to portray the interface between the CRP and the project development process. The function modeling tool captures constructability functions and information necessary to perform these functions. The research method to develop the CRP is presented. The CRP has three phases corresponding to planning, design, and construction of a transportation project. Seven constructability functions are performed in each phase. The model was tested using two transportation projects of different complexity.

This paper describes research to develop a constructability review process (CRP) for transportation facilities. This process must incorporate tools to aid in performing constructability reviews. A comprehensive review of literature and existing constructability practices provided the basis for identifying and developing 52 analytical tools for use in a CRP. Detailed descriptions of each tool were developed. Tools were classified by whether they were used to understand/communicate constructability, were used to implement/measure constructability, or were cutting edge technology/computing based. Tools were integrated into the CRP by linking a tool(s) to each constructability function of the review process. Twenty-one constructability functions were included in the final CRP model, supported by 27 basic tools. These 27 selected tools were integrated into the CRP in a user-friendly format, using tables to communicate tool concepts, rather than by merely using text. Another 25 review tools were identified as advanced tools for future application. Road maps were used to indicate the linkage between basic and future tools and the constructability functions the tools support.

Construction productivity trends carry immense consequences for the economy as a whole. However, there is little scholarly consensus concerning even the direction of such trends. The main objectives of this paper are to (1) present an approach to studying long-term productivity trends in the U.S. construction industry; and (2) provide a preliminary indication of such trends over the past 25–30 years. Subsequent, extended statistical studies are suggested that may be based on the approach of the selected work presented here. Labor cost and output productivity trends are tracked for tasks that represent different trades and differing levels of technological intensity within the building construction sector. Specific tasks dealt with a range from a zero technology impact task, such as hand trenching, to compaction with a sheepsfoot roller. Means's cost manuals were used to trace the benchmark values for these tasks. These values reflect productivity trends. Unit labor costs in constant dollars and daily output factors were compared over decades for each task. Direct work rate data from 72 projects in Austin, Tex., over the last 25 years were also examined. Increasing the direct work rate usually increases construction productivity. The combined data indicate that productivity has increased in the 1980s and 1990s. Depressed real wages and technological advances appear to be the two biggest reasons for this increase. The data also indicate that management practices were not a leading contributor to construction productivity changes over time. Subsequent studies are required to add weight to these observations and can be based on the approach presented here.

The Construction Congestion Cost System (CO³) is an integrated set of tools to estimate impact of traffic maintenance contract provisions on congestion, road user cost, and construction cost. CO³ produces realistic budgets and selects practical contracting methods that provide an acceptable balance between construction cost and congestion. This paper describes the underlying CO³ model of traffic demand, delay, and user cost, particularly the methods by which CO³ calculates traffic backup and delay, diverted and canceled trips, and road user cost. It provides examples that illustrate the CO³ model and methods. CO³ models the common characteristic of construction work zones by which road capacity can vary from hour to hour as lanes close and open and work conditions change. Traffic demand also varies with time of day, and drivers may divert to an alternate route or cancel trips because of delays caused by construction. CO³ estimates traffic delay due to traffic congestion as a function of demand and capacity, and it estimates traffic cancellations and diversions as functions of traffic delay.

The Construction Congestion Cost System (CO³) is an integrated set of tools to estimate impact of traffic maintenance contract provisions on congestion, road user cost, and construction cost. Engineers use CO³ to produce realistic budgets and select practical contracting methods that provide an acceptable balance between construction cost and congestion. This paper demonstrates computation of impacts associated with alternative methods of maintaining traffic during construction. The Routes Sheet computes equivalent average vehicle routes for complex diversion routes. The Input Sheet provides for documentation of vehicle and route inputs and computes user cost for individual trips through the work zone, diversions, and cancellations. The Traffic Sheet computes daily traffic impacts and user costs for each construction method. The Construction Sheet computes impact of different construction methods on construction costs. The Impact Sheet summarizes daily impacts and computes total project traffic impacts, road user costs, and construction costs for all alternatives. These tools provide practical information with which engineers select construction methods whose impacts are acceptable.

Rebar fabrication is a labor intensive operation that uses scrap or “trash” steel for raw materials and therefore can benefit greatly from improvements in safety, productivity, and quality. Shared control through a human-machine interface may be the best alternative for achieving highest quality standards and improving worker performance in safety and productivity. This paper develops a control scheme for automated rebar bending within the framework of computer integrated construction and presents research focused on the task level control to compensate for springback in the bent rebar. Three major problems are addressed: (1) Conception of a hierarchical computer integrated construction control structure that links rebar fabrication to the other construction project functions: (2) comparative evaluation of alternative algorithms for prediction of springback; and (3) portability of a springback control model that uses real-time electronic sensing. Bending tests were conducted with both a laboratory prototype and an actual shop table bender to experiment with alternative models for in-process springback prediction including a neural network model. Limitations in control system portability were realized in the transfer from the laboratory prototype bender to the shop bender. Springback model evaluations revealed that empirical statistical models, neural networks, and in-process relaxation performed equally well.

A contingency allowance is an amount of money used to provide for uncertainties associated with a construction project. Traditionally, it is a percentage addition on top of the base estimate. Estimating using risk analysis (ERA) is a methodology that can be used to substantiate the contingency by identifying uncertainties and estimating their financial implications. A study of the effect of ERA was carried out to compare the variability and consistency of the contingency estimates between non-ERA and ERA projects. This paper presents results of a survey that compares a total of 287 non-ERA and 45 ERA projects. The results show a highly significant difference in variation and consistency between these groups. It indicates successful use of the ERA method for public works projects to reduce unnecessary and exaggerated allowance for risk. However, the contingency allowance for ERA projects was still considered high. Improvement and refinement of the ERA method as well as recommendations on capital budgeting policy are suggested.

Cost, schedule, and quality are the main indicators of performance in construction projects. These indicators are highly interrelated and require some balance and trade-off among them to achieve efficient overall control over project performance. Focusing on these performance indicators, the primary objective of this study is to investigate the use of conventional control techniques in projects involving reconstruction of occupied buildings. To facilitate this analysis, performance data have been collected, using a questionnaire survey, from 25 reconstruction and 15 new construction projects. The survey was followed by structured interviews with construction practitioners and project participants to elicit success-related factors and to identify some of the unique problems affecting the control of reconstruction projects. Using the collected data, performance comparison was conducted between new and reconstruction projects along with a detailed analysis of the suitability of existing techniques for the control of the cost, schedule, and quality in reconstruction projects.

The purpose of this study was to develop a new concept of project control. This new concept uses stochastic S-curves (SS-Curves) as an alternative to using the deterministic S-curve technique commonly employed in professional practice. SS-curves are developed by determining the activity level variability in cost and duration. Simulation is the recommended approach for obtaining SS-curves, similar to the way that stochastic schedules are currently developed. SS-curves provide probability distributions for expected cost and duration for a given percentage of work completed. Monitoring project performance is performed by comparing the most likely budget and duration values, obtained from respective probability distributions for actual progress, with the project's actual data and cumulative cost. By using this method, an evaluation of actual project performance can be developed that appropriately considers the natural variability of construction costs and duration, rather than utilizing only one possible deterministic outcome. Given the probabilistic characteristics of SS-curves, additional benefits are presented that enable a more comprehensive project control methodology.

Many techniques are used in practice to construct underwater foundations, including caissons and piled foundations. The main challenge of underwater construction is cutting off water seepage so as to always provide dry working conditions. Water seepage can be eliminated by continually pressurizing inside caissons and dewatering the intercepted space of sheet-pile cofferdams. Although these methods alleviate water seepage, they have negative aspects, including unhygienic working conditions and elevated costs. This paper presents a method to partly construct the submerged pile caps above water, sink to place, and complete work in totally dry working conditions. This method adapts the lift-slab technology to lower the pile cap to the underwater permanent position. Only activities necessary to make the pile cap monolithic with the pile group are achieved after the cap is lowered in secured dry working conditions. This method was used successfully in many bridges on the Nile River in Egypt during the last decade. The method is illustrated in this paper along with the problems encountered during construction. Finally, the method is evaluated and compared with other methods.

Since a well-established construction information classification system (CICS) can be an information center through the life cycle of a project, it is important to use a proper CICS for managing construction information. Construction Index/Samarbetskommitten for Byggnadsfragor (CI/SfB) has been used in various countries as one of the best among the earlier CICSs as well as Masterformat in North America. CI/SfB, however, cannot represent many new construction technologies introduced during the 20 years that have passed since the last revision. Therefore, ISO developed a new CICS framework. Subsequently, the Construction Project Information Committee, including the Institution of Civil Engineers, developed the Uniclass system based on the ISO framework. Considering that Uniclass is intended to substitute for CI/SfB and that each country needs international exchange of information by the ISO standard, it is necessary to analyze the organization of Uniclass. This study analyzed the practical adaptability of Uniclass compared to CI/SfB and then suggested applicable illustrations with appropriate methodologies to improve the adaptability for civil engineering works. As a result, items classified in Uniclass gained a significant improvement for civil engineering projects compared to the existing CICSs, which have focused on architectural projects. The proposed methodologies will make the applicability of the CICS better by the improved scheme and by being consistent.