New Approach to Compare Glare and Light Characteristics of Conventional and Balloon Lighting Systems

With the increasing needs to adopt nighttime construction strategies in order to avoid disruption of traffic flow, state agencies are currently experimenting with a new class of light towers known as balloon lights. Compared to regular lighting tower, balloon lights have been reported to reduce glare significantly and to provide more uniform lighting conditions at the site. The objective of this study was to measure light and glare characteristics of two balloon lighting systems in the field. Glare and lighting characteristics of this new class of light towers were compared to a conventional lighting system. For this purpose, field measurements were made of the pavement luminance and the horizontal and vertical illuminances on a predefined experimental grid. Results of this study indicated that while being comparable in terms of wattage and luminous flux, the tested balloon light systems differed in terms of light and glare characteristics. In addition, while conventional light tower provided greater illuminance at the light source than balloon lights, the disability glare was greater for conventional light tower than balloon lights when mounted at the same height. Results of this study revealed that optimum conditions should be sought in the work zone, through which adequate lighting conditions are provided for workers while disability glare is kept below a safe threshold for drive-by motorists. Plotting the maximum veiling luminance ratio (disability glare) against the workable distance provides a simple approach to consider the two factors concurrently in the design of work zone lighting.     

Lighting Requirements for Nighttime Highway Construction

This paper presents the development of a practical framework for identifying the lighting requirements for nighttime highway construction activities. The framework is named Construction Visual Requirements, “CONVISUAL,” and is designed to consider and quantify the varying lighting needs for different visual and construction tasks. The framework is developed using an original and interdisciplinary approach that integrates concepts and models from construction engineering and vision science to ensure the provision of adequate lighting conditions on site that enable workers to properly see and perform their tasks safely and with satisfactory quality. CONVISUAL determines the required illuminance level for each construction activity based on its required visual tasks and the visual capacity of construction workers. A prototype of CONVISUAL framework is implemented to illustrate its unique capabilities of (1) providing a deeper understanding of the visual requirements of nighttime construction activities; (2) specifying the required illuminance levels in a scientific and systematic approach; and (3) delivering a rational justification for the specified illuminance levels.     

Optimal Lighting Arrangements for Nighttime Highway Construction Projects

This paper presents a decision support system for optimizing temporary lighting arrangements in nighttime highway construction projects. The system is developed as a multiobjective genetic algorithm that is capable of: (1) maximizing average illuminance on construction sites; (2) maximizing lighting uniformity in the work zone; (3) minimizing glare to workers and road users; and (4) minimizing lighting costs. The system is designed to support decision makers in their search for practical lighting arrangements that provide various tradeoffs among these four conflicting objectives. Five decision variables are optimized in the present system, namely: number of lighting equipment, equipment positioning, mounting height, aiming angle, and rotation angle. The system is also designed to consider and satisfy all practical constraints that can be encountered in this lighting design problem. An application example is analyzed to illustrate the use of the system and demonstrate its capabilities in generating near optimal and practical lighting arrangements for nighttime highway construction projects.     

Application of Linear Scheduling

Many projects, such as the construction of roadways, pipelines, and high‐rise buildings, involve repetitive activities. A method for scheduling such work, the Linear Scheduling Method (LSM) is presented. In an LSM schedule, the repetitive activities are plotted as lines of constant or varying slopes on two axes, distance versus time. Discrete activities may be shown at their appropriate times and locations and then referenced to a network schedule for additional detail. The Linear Scheduling Method is illustrated by applying it to an actual roadway construction project. The simplicity of the system and advantages for certain types of projects are revealed. A sample schedule is used to derive information that is comparable to what may be obtained from an equivalent CPM network.     

Developing a Decision Support Tool for Nighttime Construction in Highway Projects

This paper presents a decision support tool that is intended to help highway agencies in evaluating the suitability of nighttime construction for highway projects. This tool was developed as part of a research project sponsored by the Illinois Department of Transportation. The tool is a simple software package that was developed using a Microsoft Excel spreadsheet and Visual Basic for Applications. The proposed tool utilizes the cost-effectiveness analysis as a basis for comparison between daytime and nighttime operations. The proposed tool is mainly used whenever night shift is thought of as an alternative to the conventional daytime shift. Nonetheless, the tool is also generic in the sense that it can be used to compare different alternative plans such as different lane closure strategies or scheduling alternatives.     

Louisiana Highway Construction Cost Trend after Hurricanes Katrina and Rita

The objective of this study was to reveal the trend in highway construction costs following Hurricanes Katrina and Rita in Louisiana. The means of measuring highway construction cost was the Louisiana Highway Construction Index, an index made up of the cost of labor, equipment, and six major materials used in highway construction. Data from projects let by the Louisiana Department of Transportation and Development from the second quarter of 2003 to the second quarter of 2007 were used to track the change in construction costs. Index values from hurricane-impacted areas (GO Zones) were compared with those in Non-GO Zones. The indices revealed that two quarters after Hurricanes Katrina and Rita, the highway construction cost jumped about 20% statewide and 51% in GO Zone. Two years after the hurricanes, the cost has stabilized to around 30% increase over the pre-Katrina and Rita period. This study provides valuable information for the state agency to estimate cost escalation in ongoing projects and to estimate future disaster response to highway construction costs.     

Time, Cost, and Quality in a Road Building Project

Time, cost and quality are the three factors that play a significant role in the planning and controlling of construction projects. The main barriers for their achievement are the changes in the project environment necessitating cost, time, and quality trade-offs. Literature has mainly focused on analyzing time and cost with little or no reported research focusing on models for optimizing construction time, cost, and quality jointly. Government agencies have recently started using new types of contracting methods which have placed an increasing pressure on decision makers in the construction industry to search for an optimal/near optimal resource utilization plan that minimizes construction cost and time while maximizing its quality. In this paper, a 0-1 Integer Programming model which enables meeting quality output standards and time and budget objectives respectively is developed. The clever use of binary variables allows us to solve many interesting and difficult problems and our ability to model complex problems increases tremendously when we use binary variables. A version of the model to minimize time meeting quality and cost objectives is applied to a road building project. Two alternatives versions of the model which enable to minimize cost meeting quality and time and to maximize quality meeting time and cost, are shown in an Appendix.     

设备检修安装工程签证在项目造价控制中的作用

介绍了设备检修安装项目造价管理中现场工程量签证暴露的问题,进行了理论分析,并对其中的关键环节提出了改进措施,在有效缩减一定比例项目造价的同时,真实客观地反映设备检修安装工程造价。     

Estimating Work Zone Road User Cost for Alternative Contracting Methods in Highway Construction Projects

Highway construction often causes an additional road user cost (RUC) to motorists due to traffic flow interruption and congestion in work zones. Consequently, facility owners, such as the Florida Department of Transportation (FDOT), are often interested in using alternative contracting methods such as A+B contracting to expedite construction. Although many of these contracting methods rely on the RUC to determine incentives or disincentives, no standard method for RUC calculation is available to FDOT district engineers. In addition, existing methods are neither practical nor user-friendly for determining incentives or disincentives. This study intends to develop a RUC calculation procedure for the FDOT that focuses on using data that are easily accessible to FDOT district engineers, such as drawings and maintenance of traffic plans. The procedure is developed based on traffic analysis methods published in the Highway Capacity Manual, previous studies on user benefit analysis and work zones, and empirical data specific to Florida. Case studies are used to illustrate the procedure and to compare it with two other existing models, the Arizona model and the queue and user cost evaluation of work zone model, through correlation analysis, comparison of calculation assumptions, and data input analysis. This study shows that the suggested procedure produces consistent RUC estimates.     

Modeling the Dynamics of Heavy Equipment Management Practices and Downtime in Large Highway Contractors

Machine downtime is invariably perceived as one of the most critical problems faced by highway contractors. Attempts to reduce downtime often result in failure due to the dynamic behaviors between equipment management practices and downtime. This paper is thus intended to highlight the dynamics of heavy equipment management practices and downtime in large highway contractors and utilizes them as a framework in constructing a simulation model using a system dynamics approach. Face-to-face interviews were conducted with equipment managers from five different large highway contractors in Thailand. The finding reveals that, to be successful in alleviating downtime, contractors must view their practices on equipment management as an integration of multiple feedback processes, which are interrelated and interdependent with downtime. Based on various validation tests, the simulation model is deemed appropriate in representing the equipment management system as related to downtime of large highway contractors. The research is of value in facilitating better understanding on the dynamics of equipment management practices and downtime as well as their interdependency.     

Line‐of‐Balance Scheduling in Pavement Construction

Linear Scheduling Methods are best suited to projects that display repetitive characteristics, but their use in the construction industry is limited. Line‐of‐Balance (LOB) is a Linear Scheduling Method that also makes use of network technology. Its benefits and shortcomings are investigated in a high‐way surface treatment project where LOB has been used experimentally. It was determined that LOB is extremely sensitive to errors in man hour, crew size, and activity duration estimates. There are also problems of a visual nature with the presentation of the diagram. On the other hand, LOB allows a better grasp of the project than any other scheduling technique because it is possible to adjust activities' rates of production. It provides a smooth and efficient flow of resources and requires less time and effort to produce than network schedules. Research to make Linear Scheduling Methods more attractive is recommended.     

Work Inputs and Related Economic Aspects of Multitier Shoring Towers

Shoring towers are the common formwork solution for high-clearance construction. Because towers account for a remarkably high percentage of the cost of the constructed concrete element, work input data and related economic aspects of tower erection constitute important information for constructors. This paper presents three case studies of high multitier shoring towers, each representing a different tower type. Tower data, major construction parameters, and work inputs for each case are presented. Findings are compared and discussed, and due conclusions are drawn. Finally, recommendations on measures expected to increase the economy of shoring solutions using multitier towers are offered, and some restrictions on the adoption of work input data are listed.     

Impact of Government and Corporate Strategy on the Performance of Technology Projects in Road Construction

In this study, we focus on road construction and analyze technology development projects. Based on the business strategy literature and literature on technology policy, we test the relative importance of a firm’s strategies and government as a buyer and champion. Our empirical findings stress the value of government championing behavior. Our results show that in road construction, championing behavior is more important than public technology procurement for project performance. The results even suggest that government championship is more important than a firm’s strategic orientation.     

Estimating Cost Discrepancies in Highway Contracts: Multistep Econometric Approach

This paper investigates the likelihood of occurrence and quantifies the magnitude and rate of discrepancies in highway project final costs with respect to their contract award amounts. Using data from Indiana, we develop a multistep econometric approach that can be used to estimate the effects of factors associated with the contract bidding process, project type, and the project physical environment on cost discrepancies in highway contracts. Estimation findings indicate that for a given project type and project year, contracts of larger size or longer duration are generally more likely to incur cost overruns. In addition, for contracts that incur cost overruns, the cost overrun rate decreases nonlinearly with increasing contract size up to a certain point after which the cost overrun rate increases with increasing contract size. Our approach allows for the possibility that cost overrun amounts are not linearly related to contract award amounts (contract size), and shows that greater analytical flexibility needs to be incorporated into any investigation of contract cost overruns. Agencies interested in improving their financial forecasts can replicate our proposed methodology using local contract data.     

Alternative Project Delivery Systems: Applications and Legal Limits in Transportation Projects

This paper presents the results of a comprehensive survey of the legal codes of all the 50 states in the United States regarding alternative project delivery systems in transportation projects. In the past decade there has been a surge of legislation allowing state transportation officials much more flexibility regarding the choice of project delivery systems. These delivery systems are usually selected based on a combination of price and quality. Specific delivery systems studied in this paper are Design-Build, Construction Management at Risk, and Public-Private-Partnership. The background and history of the emergence of these new delivery systems are studied in this paper. The research showed that in many states, alternative delivery systems may be allowed but with specific restrictions. For each state, all of these delivery systems have been researched and placed into one of the following distinguishable categories: (1) fully authorized; (2) authorized but needs extra approvals; (3) authorized for a pilot program and/or with some limitations; (4) not authorized. The output of the survey gives valuable snapshots over the status of each delivery system in regards to its legality in different parts of the country as of December 2006. Comparing the results of this survey with the surveys done previously shows that the trend is to allow states more flexibility in the choice of project delivery systems.     

How to Evaluate and Invest in Emerging A/E/C Technologies under Uncertainty

Many emerging architectural/engineering/construction (A/E/C) technology investments are of strategic importance and may create future growth opportunities. Therefore, from the strategic perspective, management needs a better method that can quantify the strategic value of technology investment and suggest optimal investment strategies when the future is uncertain. This paper presents a quantitative valuation method based on modern option pricing theory for evaluating major investments in emerging A/E/C technologies. This framework considers specifically the technology investment risk and embedded managerial options. It further aligns the investment evaluation process with the financial market. The analysis may help A/E/C firms more accurately evaluate investments in emerging technologies, such as information technology and automation, and make strategic investment decisions under uncertainty.     

Contributors to Construction Debris from Electrical and Mechanical Work in Hong Kong Infrastructure Projects

The crucial problem of construction debris is of increasing concern in Hong Kong. In the construction industry, the electrical and mechanical (E&M) installations in the infrastructure, for example, buildings, tunnels, or dams, are some of the major and usually complex components. Difficulty in coordinating the various trades affects productivity in general, and has a major impact on the quantity of construction debris. By identifying the sources of waste at each stage of E&M engineering work, some of the construction debris can be eliminated at the source during production. This paper investigates the critical production shortcomings in the E&M sector in Hong Kong. The study is based on a survey that includes a preliminary questionnaire survey, brainstorming exercises with a focus group, structured interviews with experienced frontline supervisors, and a second focus group exercise to test findings and proposed measures. The principal findings are that “poor coordination” and “design changes and/or errors” are major contributors to variations or change orders and rework, which in turn result in a high volume of construction debris. The results also indicate that construction debris can be minimized in the E&M sector of the construction industry, if the material wastes from incidental work are reduced and also controlled better in a new work process flow pattern through recommended construction project management improvements for reducing critical production shortcomings.     

抗震区框架梁柱施工中钢筋分项工程质量控制

从钢筋的材质、钢筋的搭接位置、箍筋加密区的安装、梁柱节点钢筋施工、变截面处柱钢筋的锚固等方面论述抗震设防区框架梁柱施工中钢筋分项工程的质量控制。     

谈如何做好通风与空调工程施工质量的现场监理控制工作

通风与空调工程作为建筑工程的组成部分,是后期实现房屋建筑使用功能的重要基础。因此,通风与空调工程的施工质量对于建筑的功能性及居住体验有着重大影响。通过分析通风与空调工程的重点施工细节,剖析影响施工质量的因素,探讨如何针对性的做好通风与空调工程施工质量的监理控制工作。