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.     

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.     

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.     

Effectiveness of Speed Control Measures on Nighttime Construction and Maintenance Projects

Nighttime work-zone safety has become a concern among state transportation agencies due to an increasing number of work-zone fatalities and the high percentage of roadwork performed at night. Speed control has been determined by numerous researchers to be one of the best ways to improve safety on nighttime work zones. This paper presents an empirical analysis of speed-control strategies for nighttime interstate construction and maintenance projects in Indiana. The analysis considers the effect of various speed-control measures on the mean speed and the standard deviation of speed through nighttime work zones. Using a seemingly unrelated regression modeling approach, the present analysis revealed that the presence of police enforcement, a high percentage of semitrucks in the traffic stream, and a high traffic flow significantly reduced mean work-zone speeds. Factors found to significantly increase mean work-zone speeds included an increase in the number of open lanes, an original speed limit of the road section greater than 100 km/h (62 mi/h) an increase in the distance between the work-zone speed-limit signs and the first cone/barrel in the construction zone taper, and the progression of time through the night. The standard deviation of vehicle speeds was found to be significantly lower before midnight and as the number of vehicles queued increased. It was found to be significantly higher with an increase in the number of open lanes through the work zone, an increase in the number of worksite speed-limit signs, a high percentage of personal vehicles in the traffic, and an increase in total traffic flow. The results from this research demonstrate a useful analysis methodology (seemingly unrelated regression estimation) and provide some empirical results that can provide guidance for transportation agencies and contractors to improve speed-control strategies in nighttime work zones.     

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.     

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.     

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.     

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.     

Guidelines for Warranty Contracting for Highway Construction

This paper presents guidelines for implementing the construction warranty contracting method in the highway construction industry. A logical, step-by-step method for effectively applying the warranty contracting program for use in the highway construction industry is developed. Relevant issues that may present obstacles to the implementation are addressed, while the best practices, compiled from an evaluation of the current industry’s state-of-the-art practices, will assist an interested state highway agency in creating a warranty specification. In performing this research, the current use of warranty specifications among state highway agencies was examined, and an in-depth case study of the Wisconsin Department of Transportation’s warranty program was conducted.     

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.     

Human-Assisted Obstacle Avoidance System Using 3D Workspace Modeling for Construction Equipment Operation

Equipment operation on construction sites is a major source of construction accidents and injuries related to crushing, electrocution, and falls. Primarily, this is because the operator’s field of view, reaction speed, attention, and depth perception are limited, and also because the construction site is a dynamic environment. Accelerating advances in sensing and equipment control sophistication present new opportunities to address these safety problems. The research described here provides the basis for the development of obstacle-avoidance systems that use models of objects generated by rapid three-dimensional (3D) workspace modeling methods and by sophisticated equipment control capabilities. An explanation of the proposed obstacle avoidance system, together with preliminary results, is presented. Implementation of this system in practice is feasible in the near term for critical and particularly hazardous operations.     

Distributed Ontology Architecture for Knowledge Management in Highway Construction

The ongoing plethora of rehabilitation in the infrastructure domain requires more planning and integration during design and construction. To achieve this, there is a need for developing and using semantic (ontology-based) mechanisms for the exchange of development knowledge among all project stakeholders. This paper presents a distributed ontology architecture for knowledge management in highway construction. With every other utility tied to the highway geometry, the architecture is intended to be the base for a cross-discipline knowledge exchange in the infrastructure domain. The architecture presents highway knowledge on three levels: domain knowledge (an umbrella for infrastructure shared knowledge), application knowledge (representation of highway-specific knowledge), and user knowledge (an enterprise-specific representation of highway knowledge). The proposed architecture models highway concepts using six major root concepts: project, process, product, actor, resources, and technical topics (attributes and constraints). The architecture was developed using rigorous knowledge acquisition and ontology development techniques. It was developed as an extension for the e-COGNOS ontology. The architecture was validated through input from domain experts.     

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.     

Time-Cost-Quality Trade-Off Analysis for Highway Construction

Many departments of transportation have recently started to utilize innovative contracting methods that provide new incentives for improving construction quality. These emerging contracts place an increasing pressure on decision makers in the construction industry to search for an optimal resource utilization plan that minimizes construction cost and time while maximizing its quality. This paper presents a multiobjective optimization model that supports decision makers in performing this challenging task. The model is designed to transform the traditional two-dimensional time-cost tradeoff analysis to an advanced three-dimensional time-cost-quality trade-off analysis. The model is developed as a multiobjective genetic algorithm to provide the capability of quantifying and considering quality in construction optimization. An application example is analyzed to illustrate the use of the model and demonstrate its capabilities in generating and visualizing optimal tradeoffs among construction time, cost, and quality.     

Compliance Guide for a Proposed Highway Project to Meet National Environment Protection Act Requirements

The National Environmental Protection Act (NEPA) requires that, prior to construction of a highway, the head of the federal agency that is committing funds to the project must evaluate the effect of the project on the human environment; the effect of the project on the habitat of an endangered species, which implicates provisions of the Endangered Species Act, the effect of the project on any historic properties in the vicinity of the project, which implicates provisions of the National Historic Preservation Act, and the effect of the project on minority or low-income populations, called environmental justice, which implicates Title VI of the Civil Rights Act of 1964. In this paper, we provide an example guide for transportation planners to follow as they comply with NEPA and the related acts in the beginning planning stages for a highway project.     

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.     

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.     

Risk Assessment in Construction

This study is concerned with the assessment of risk for major construction activities. Risk has been defined as a measure of the probability, the severity, and the exposure of all hazards of an activity. A risk assessor model (RAM) was developed and computerized to determine the risk associated with a particular activity and the justification factor for a proposed remedy. Knowing the value of risk would help contractors identify the high risk of major construction activities and would enable them to allocate safety precautions in a more efficient manner.     

Neural Network Modeling of Highway Construction Costs

The objective of this research was to develop a procedure that estimates the escalation of highway construction costs over time. An artificial neural network model was developed which relates overall highway construction costs, described in terms of a highway construction cost index, to the cost of construction material, labor, and equipment, the characteristics of the contract and the contracting environment prevailing at the time the contract was let. Results demonstrate that the model is able to replicate past highway construction cost trends in Louisiana with reasonable accuracy. Future construction input costs are estimated from commercially available forecasts of indicator variables closely associated with the price of construction labor, construction equipment, and a representative set of highway construction materials. Future contract characteristics and the contracting environment that is likely to exist in the future are estimated from past trends or stipulated to be consistent with policy decisions in the future. The predictions produced by the model estimate that highway construction costs in Louisiana will double between 1998 and 2015.     

Simplified Discrete-Event Simulation Approach for Construction Simulation

The methodology of discrete-event simulation provides a promising alternative solution to designing and analyzing dynamic, complicated, and interactive construction systems. In this paper, an attempt is made to extend the previous work of simplifying construction simulation by delving into the fundamental approaches for discrete-event simulation. A new simplified discrete-event simulation approach (SDESA) is presented through extracting the constructive features from the existing event/activity-based simulation methods; both the algorithm and the model structure of simulation are streamlined such that simulating construction systems is made as easy as applying the critical path method (CPM). Two applications based on real road construction projects in Hong Kong serve as case studies to illustrate the methodology of simulation modeling with SDESA and reveal the simplicity and effectiveness of SDESA in modeling complex construction systems and achieving the preset objectives of such modeling. They are a granular base-course construction system featuring both cyclic and linear processes and an asphalt paving construction system with complicated technological/logical constraints. As a general-purpose method for construction planning, SDESA enables practitioners to deal with what the CPM-based network analysis method fails to solve by offering discrete-event simulation capabilities. Furthermore, the SDESA can potentially be adapted to special-purpose simulation tools to tackle large and complicated construction systems of practical size that have yet to find convenient solutions with existing simulation methods.