CONLIGHT: Lighting Design Model for Nighttime Highway Construction

The utilization of nighttime work in highway construction and rehabilitation projects has been increasing in recent years throughout the United States. In this type of projects, construction planners are required to develop and submit a lighting plan that provides: (1) adequate illuminance levels for all planned nighttime construction tasks; (2) reasonable uniformity of light distribution in the work area, and (3) acceptable glare levels to both road users and construction workers. In order to support construction planners in this vital and challenging task, this paper presents a lighting design model, named CONLIGHT, which is capable of considering the specific requirements of nighttime highway construction operations. The model is developed to enable construction planners to evaluate the performance of various lighting plans and select a practical design that complies with all lighting requirements for the nighttime work being planned. An application example is analyzed to illustrate the use of the model and demonstrate its accuracy and capabilities in generating practical lighting plans for nighttime construction and rehabilitation projects.     

Field Experiments to Evaluate and Control Light Tower Glare in Nighttime Work Zones

An increasing volume of highway repair and construction work is being performed during the off-peak nighttime hours to mitigate the impact of construction-related daytime traffic congestions and shorten the duration of construction operations. The utilization and placement of light towers to illuminate the work zone in this type of construction can cause harmful levels of glare for both drivers and construction workers. This paper presents the results of field experiments which were conducted to (1) study the levels of glare and lighting performance generated by light towers in and around nighttime work zones; (2) analyze the combined impact of the light tower set up parameters including its height as well as its aiming and rotation angles on glare and lighting performance; and (3) provide practical recommendations to reduce and control lighting glare in and around nighttime work zones. The results of these experiments confirm that the set up of light towers has a significant impact on glare and therefore it should be carefully designed and executed on nighttime highway construction projects to ensure the safety of the traveling public as well as construction workers.     

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.     

Minimizing Construction-Related Hazards in Airport Expansion Projects

Airport expansion projects often require the presence and movement of construction labor and equipment near critical airport traffic areas. This close proximity between construction activities and airport operations needs to be carefully considered during the planning of construction site layouts in order to minimize and eliminate all potential construction-related hazards to aviation safety. This paper presents the development of a multiobjective optimization model for planning airport construction site layouts that is capable of minimizing construction-related hazards and minimizing site layout costs, simultaneously. The model incorporates newly developed optimization functions and metrics that enable: (1) maximizing the control of hazardous construction debris near airport traffic areas; (2) minimizing site layout costs including the travel cost of construction resources and the cost of debris control measures on airport sites; and (3) satisfying all operational safety constraints required by the federal aviation administration as well as other practical site layout constraints. The model is implemented using a multiobjective genetic algorithm and an application example is analyzed to demonstrate the use of the model and its capabilities in optimizing construction site layouts in airport expansion projects.     

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.     

Developing a Traffic Closure Integrated Linear Schedule for Highway Rehabilitation Projects

In recent years, the state departments of transportation have implemented a number of highway rehabilitation projects across the country. These projects differ fundamentally from new highway projects in that they require an uninterrupted flow of traffic throughout both the duration and geometric length of the project. Synchronization of traffic closure with the construction activities is crucial in such projects to avoid the traffic conflicts and prevent idle time for equipment and labor. Although most highway rehabilitation projects involve predominantly linear activities, the techniques of linear scheduling are not readily applicable to highway rehabilitation projects due to the conflict between the workzone and traffic flow. This paper documents the development of a traffic closure integrated linear schedule (TCILS) that addresses both traffic closure and work progress issues. The TCILS generates a single schedule for both the construction activities and the associated traffic closures. Visual and graphical features are also applied in the system, which makes it particularly applicable for highway rehabilitation projects. An actual concrete pavement rehabilitation project using the TCILS is presented as a sample of application. The findings from the sample project, although they are limited, show that the TCILS can be applied to an actual project. With recommended future development, the system is believed to be beneficial for both construction practitioners and academics.     

Minimizing Construction-Related Security Risks during Airport Expansion Projects

Airport expansion projects often require the presence of construction personnel, material, and equipment near airport secure areas/facilities, leading to an increase in the level of risk to airport security. Construction planners and airport operators need to carefully study this challenge and implement active measures in order to minimize construction-related security breaches and comply with all relevant Federal Aviation Administration guidelines. This paper presents the development of an advanced multiobjective optimization model for planning airport construction site layouts that is capable of minimizing construction-related security breaches while simultaneously minimizing site layout costs. The model incorporates newly developed criteria and performance metrics that enable evaluating and maximizing the construction-related security level in operating airports. The model is developed using a multiobjective genetic algorithm, and an application example is analyzed to demonstrate the use of the model and its unique capability of generating a wide spectrum of optimal trade-offs between construction-related airport security and site layout costs.     

Planning and Scheduling Highway Construction

This paper presents a model designed to integrate the planning and scheduling phases of highway construction projects, focusing primarily on the planning aspects. The model automatically generates the work breakdown structure (WBS) and precedence network respecting job logic and stores a list of construction operations typically encountered in highway projects. The generated network can subsequently be modified to suit the unique requirements of the project being considered. An object-oriented model is developed for planning highway construction operations. The model employs resource-driven scheduling in order to suit the repetitive nature of this class of projects. It accounts for (1) resource availability; (2) multiple preceding and succeeding activities; (3) transverse obstructions; (4) activities with varying quantities of work along the highway length; (5) the impact of inclement weather on crew productivity; and (6) the beneficial effect of the learning curve. At the core of the model is a relational database designed to store available resources and their respective unavailability periods. The model enables both: (1) activities executed by own force; and (2) activities subcontracted out. The model is incorporated in a prototype software that operates in the Microsoft Windows environment and generates schedules in both graphical and tabular formats. An example project is analyzed to demonstrate the features of the developed model.     

Trade-off between Safety and Cost in Planning Construction Site Layouts

Planning construction site layouts involves identifying the positions of temporary facilities on site, and accordingly it has a significant impact on the safety and efficiency of construction operations. Although available models are capable of minimizing the travel cost of resources on site, they do not consider safety as an important and separate objective in the optimization of site layouts. This paper presents the development of an expanded site layout planning model that is capable of maximizing construction safety and minimizing the travel cost of resources on site, simultaneously. The model incorporates newly developed concepts and performance criteria that enable the quantification of construction safety and travel cost of resources on site. The present model is developed in three main phases: (1) formulating decision variables and optimization objectives in this site layout planning problem; (2) identifying and satisfying all practical constraints in this optimization problem; and (3) implementing the model as a multiobjective genetic algorithm. An application example is analyzed to illustrate the use of the model and demonstrate its capabilities in optimizing construction site layouts and generating optimal trade-offs between safety and travel cost of resources on site.     

Study of Factors Influencing the Efficient Management and Downtime Consequences of Highway Construction Equipment in Thailand

Downtime resulting from machine breakdown invariably has a considerable impact on the performance of construction projects and companies as a whole, especially to contractors with heavy investment in equipment. Attempts to investigate the causes and consequences of downtime are rarely found. The aim of this paper is to characterize and quantify factors that influence downtime consequences (consequential problems resulting from downtime) of highway construction equipment based on the structural equation modeling (SEM) approach. A questionnaire survey was conducted to collect data on equipment management practices and downtime consequences among highway contractors in Thailand. The SEM model proposed is of value for both researchers and practitioners to facilitate a better understanding of the relationships among acquisition condition, operational practice, maintenance quality, disposal practice, and downtime consequence of heavy equipment. The model also helps contractors to manage equipment more efficiently by concentrating on several practices that can convey the greatest benefit in minimizing downtime consequences at each particular stage of a machine’s life cycle, rather than considering all practices simultaneously where the benefits gained are perhaps not proportional to the effort.     

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.     

Long‐Range Forecasting Highway Construction Costs

In the process of decision making for design and execution of highway construction projects, long‐range cost forecasting is one of the most significant and complicated problems. This paper describes the development of a model that enables the user to make long‐range cost projections, taking into consideration general characteristics of the highway construction industry, as well as pertinent local conditions. The model presented uses conventional statistical methods to represent the main categories of typical jobs in the highway construction industry. From these categories, a composite model is created by assigning different weights to the input elements costs and then choosing a series of indicators to predict price trends for each separate element of the composite model. Use of this model reveals that bid volume in a certain area is a factor that has significant influence upon cost forecasts. This paper is accompanied by a case study based on actual data from highway construction projects performed for the Florida Department of Transportation in the years 1968–1981.     

悬索桥隧道锚开挖施工技术研究

高速公路悬索桥隧道锚是一个倾角大、断面逐渐加大的大跨度隧道结构,其开挖施工技术难度大,常规机械设备难以在此种条件下施展。为此,通过总结宜泸渝高速公路南溪长江大桥泸州岸隧道式锚碇开挖施工技术,对开挖过程中的各个施工环节进行介绍和分析,提出针对此种隧道结构形式开挖的施工工艺和设备要求,该研究成果对类似工程的施工具有一定的借鉴价值和指导作用。     

Optimization Research: Enhancing the Robustness of Large-Scale Multiobjective Optimization in Construction

Many construction planning problems require optimizing multiple and conflicting project objectives such as minimizing construction time and cost while maximizing safety, quality, and sustainability. To enable the optimization of these construction problems, a number of research studies focused on developing multiobjective optimization algorithms (MOAs). The robustness of these algorithms needs further research to ensure an efficient and effective optimization of large-scale real-life construction problems. This paper presents a review of current research efforts in the field of construction multiobjective optimization and two case studies that illustrate methods for enhancing the robustness of MOAs. The first case study utilizes a multiobjective genetic algorithm (MOGA) and an analytical optimization algorithm to optimize the planning of postdisaster temporary housing projects. The second case study utilizes a MOGA and parallel computing to optimize the planning of construction resource utilization in large-scale infrastructure projects. The paper also presents practical recommendations based on the main findings of the analyzed case studies to enhance the robustness of multiobjective optimization in construction engineering and management.     

Estimating Future Highway Construction Costs

The objective of this research was to develop a model that estimates future highway construction costs in Louisiana. The model describes overall highway construction cost in terms of a highway construction cost index. The index is a composite measure of the cost of construction labor, materials, and equipment; the characteristics of contracts; and the environment in which contracts are let. Future construction costs are described in terms of predicted index values based on forecasts of the price of construction labor, materials, and equipment and the expected contract characteristics and contract environments. The contract characteristics and contract environments that are under the control of highway agency officials, can be manipulated to reflect future cost-cutting policies. Application of the model in forecasting to highway construction costs in Louisiana shows that the model closely replicates past construction costs for the period 1984–1997. When applied to forecasting future highway construction costs, the model predicts that highway construction costs in Louisiana will double between 1998 and 2015. Applying cost-cutting policies and assuming input costs are 20% less than anticipated, the model estimates highway construction costs will increase by 75% between 1998 and 2015.     

CONSCOM: An OO Construction Scheduling and Change Management System

In a companion paper, an object-oriented (OO) information model was presented for construction scheduling, cost optimization, and change order management (CONSCOM), based on the creation of a domain-specific development framework. The framework architecture is developed using generic software design elements, called patterns, which provide effective low-level solutions for creating, organizing, and maintaining objects. The OO model has been implemented in a prototype software system for management of construction projects, called CONSCOM, using the Microsoft Foundation Class library in Visual C++. CONSCOM is particularly suitable for highway construction change order management. It can be used by the owner as an intelligent decision support system in schedule reviews, progress monitoring, and cost-time trade-off analysis for change order approval. The OO information model for construction scheduling cost management can be integrated into a concurrent engineering model for the architecture, engineering, and construction industry.     

Optimum Planning of Highway Construction under A + B Bidding Method

In recent years, many departments of transportation in the United States have started to apply the A + B bidding method in highway projects in order to reduce construction time and minimize its associated traffic congestion and adverse impact on local economies. The application of this method places an increased pressure on contractors to minimize both the time and cost of highway construction. This paper presents a practical model for optimizing resource utilization in highway projects that utilize the A + B bidding method. The model is designed to minimize the total combined bid by identifying the optimum crew formation and the optimum level of crew work continuity for each activity in the project. The model is developed using a dynamic programming formulation and is incorporated in a Windows application that provides a user-friendly interface to facilitate the optimization analysis. An application example of a highway project is analyzed to illustrate the use of the model and to demonstrate its capabilities.     

Simplified Spreadsheet Solutions.?I: Subcontractor Information System

This paper presents a subcontractor information system (SIS) to support the estimating and project control functions of subcontractors and small∕medium-size contractors. For the proposed SIS to be simple and practical, it was developed in a spreadsheet program designed to maintain information related to resources and projects and to generate important business reports. Resource data are stored in six worksheets for labor, equipment, crews, material, subcontractors, and alternative methods of construction for various tasks. In addition, a separate worksheet is designed for each project to be used for estimating and control purposes. The latter worksheet allows the user to specify the work breakdown structure and optional methods for construction. As such, it represents a transparent estimating model that allows for quick what-if analysis regarding time and cost. In addition, the reporting worksheet provides information related to time, cost, and resource use at the individual and the multiproject levels. In a companion paper, the use of the SIS as basis for overall schedule optimization is described.     

Impact of Rainfall on the Productivity of Highway Construction

Heavy rainfall often leads to complete suspension of highway construction due to saturated and unworkable soil conditions. Therefore, quantifying the impact of rainfall on the productivity of highway construction is essential in preparing realistic schedules and cost estimates for the preconstruction stage and in analyzing weather-related claims for the postconstruction stage. This paper presents a decision support system for quantifying the impact of rainfall on productivity and duration of common highway construction operations, namely: earthmoving, construction of base courses, construction of drainage layers, and paving operations. The system incorporates a knowledgebase and a database. The knowledgebase includes if∕then type rules, acquired from experts in highway construction operations, and the database contains hourly records of weather parameters from the closest weather station to the construction site. The system, named WEATHER, is a software system that provides user-friendly interface, including menus, dialog boxes, and graphical capabilities to facilitate data input and output.     

Scheduling∕Cost Optimization and Neural Dynamics Model for Construction

A general mathematical formulation is presented for the scheduling of construction projects and is applied to the problem of highway construction scheduling. Repetitive and nonrepetitive tasks, work continuity constraints, multiple-crew strategies, and the effects of varying job conditions on the performance of a crew can be modeled. An optimization formulation is presented for the construction project scheduling problem, with the goal of minimizing the direct construction cost. The nonlinear optimization is then solved by the neural dynamics model developed recently by Adeli and Park. For any given construction duration, the model yields the optimum construction schedule for minimum construction cost automatically. By varying the construction duration, one can solve the cost-duration trade-off problem and obtain the global optimum schedule and the corresponding minimum construction cost. The new construction scheduling model provides the capabilities of both the critical path method (CPM) and linear scheduling method (LSM) approaches. In addition, it provides features desirable for repetitive projects, such as highway construction, and allows schedulers greater flexibility. It is particularly suitable for studying the effects of change order on the construction cost. This research provides the mathematical foundation for development of a new generation of more general, flexible, and accurate construction scheduling systems.