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Challenges associated with ensuring the accuracy and reliability of cost estimation of highway construction bid items are of significant interest to state highway transportation agencies. Even with the existing research undertaken on the subject, the problem of inaccurate estimation of highway bid items still exists. This paper aims to assess the accuracy of the cost estimation methods employed in the selected studies to provide insights into how well they perform empirically. Additionally, this research seeks to identify, synthesize and assess the impact of the factors affecting highway unit prices because they affect the total cost of highway construction costs.

This paper systematically searched, selected and reviewed 105 papers from Scopus, Google Scholar, American Society of Civil Engineers (ASCE), Transportation Research Board (TRB) and Science Direct (SD) on conceptual cost estimation of highway bid items. This study used content and nonparametric statistical analyses to determine research trends, identify, categorize the factors influencing highway unit prices and assess the combined performance of conceptual cost prediction models.

Findings from the trend analysis showed that between 1983 and 2019 North America, Asia, Europe and the Middle East contributed the most to improving highway cost estimation research. Aggregating the quantitative results and weighting the findings using each study's sample size revealed that the average error between the actual and the estimated project costs of Monte-Carlo simulation models (5.49%) performed better compared to the Bayesian model (5.95%), support vector machines (6.03%), case-based reasoning (11.69%), artificial neural networks (12.62%) and regression models (13.96%). This paper identified 41 factors and was grouped into three categories, namely: (1) factors relating to project characteristics; (2) organizational factors and (3) estimate factors based on the common classification used in the selected papers. The mean ranking analysis showed that most of the selected papers used project-specific factors more when estimating highway construction bid items than the other factors.

This paper contributes to the body of knowledge by analyzing and comparing the performance of highway cost estimation models, identifying and categorizing a comprehensive list of cost drivers to stimulate future studies in improving highway construction cost estimates.

Various approaches have emerged to assist practitioners in making more informed decisions in highway construction projects. However, industry practitioners are still using subjective ways to make decisions. Also, researchers have developed tools and techniques with similar objectives. Lack of information on what has been developed might lead to those issues. Therefore, this paper aims to review trends of evolution, pinpoint strengths and gaps in the literature and identifies potential future directions for decision-making research in highway construction projects.

A systematic review was conducted on published articles on decision-making in highway construction projects using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) technique.

The analysis of 101 articles revealed that existing decision-making research in highway construction projects targets improvements in four areas: feasibility, conceptual, detailed scope and detailed design. The four areas consist of sixteen subthemes that are detailed in this study. In addition, most research involved developing decision support tools and systems as well as decision-making models, techniques and frameworks. Lastly, several research areas have emerged, such as adding more decision criteria including those with uncertainties, expanding existing decision-making models into decision support systems, benchmarking decision criteria between different sample populations and exploring inter-and intra-relationships between decision criteria.

This paper provides an overview of existing research on decision-making in highway construction projects. Also, it reveals research gaps in the body of knowledge to point out directions for future research. Finally, industry practitioners can use the findings to develop strategies for effective decision-making processes.

According to the Federal Highway Administration (FHWA), and based on its professional judgment, it typically takes from 9 to 19 years to plan, gain approval for, and construct a new, major federally funded highway project that has significant environmental impacts. However, these projects constitute only 3 percent of all federally funded projects, according to FHWA. Officials in federal and state agencies and other knowledgeable organizations indicate that delivering larger, more complex or controversial projects may take longer to complete than is typical for most highway projects. In addition to needing more time because of their size and complexity, they often take longer to complete because they must comply with more federal and state requirements and because of the public interest that they may generate. Federal and state agencies have undertaken several initiatives to improve completion times for highway construction projects. Most of these initiatives address opportunities for reducing the time required to obtain environmental approvals.

Public-private partnership (PPP) highway projects in India are undertaken at both state and national levels, such that differences exist in how the procuring authorities manage project risk during the development and construction phase under different institutional frameworks. This study assesses the performance implication of the different administrative positionings of the procuring authority.

A data set of 516 PPP highway projects implemented in India formed the basis of this study. Means comparison, ordinary least squares (OLS) regression and seemingly unrelated regression were used to assess the impact of procuring authority on schedule performance.

The findings suggest that the state and the national highway projects were no different in achieving financial closure. However, the administrative positioning of the procuring authorities had a significant impact on other schedule performance variables. The construction of the state highway projects started quickly after the financial closure compared to the national highway projects. Moreover, the state highway projects were not only planned to be implemented at a faster rate but they were actually implemented at a faster rate and had a lower time overrun.

Procuring authorities under the state governments, being closer to the project, are better placed to manage project risk than those under the national government.

The administrative distance of the procuring authority from the PPP project and its implication on performance has never been studied.

Evaluating the implementation of environmental management plans (EMPs) in highway construction projects is essential to avoid climate change. Public evaluations can help ensure that the EMP is implemented correctly and efficiently. To allow public evaluation of EMP implementations, this study aims to investigate performance indicators (PIs) for assessing EMP implementation in highway construction projects. To that end, the study objectives are to compare the critical PIs between environment auditors (EAs) and environment officers (EOs) and among the main project stakeholders (i.e. clients, contractors and consultants), create components for the critical PIs and assess the efficiency of the components.

The paper identified 39 PIs from interviews with environmental professionals and a systematic literature review. Then a questionnaire survey was developed based on the PIs and sent to EAs and EOs. The data were analyzed via mean score ranking, normalization, agreement analysis, factor analysis and fuzzy synthetic evaluation (FSE).

The analyses revealed 21 critical PIs for assessing EMP implementation in highway construction projects. Also, the critical PIs can be grouped into four components: ecological, pollution, public safety and ecological. Finally, the overall importance of the critical PIs from the FSE is between important and very important.

To the best of the authors’ knowledge, this paper is the first-of-its-kind study on the critical PIs for assessing EMP implementation in highway construction projects.

The purpose of this study is to determine whether there is a correlation between mobilization costs and project schedule performance of highway projects. In addition to this, the study will also determine if the mobilization costs are helping small or large highway projects in terms of improving the schedule performance.

The data of 206 highway projects were collected from the Department of Transportation of two states with the help of questionnaire survey. The cost, schedule and mobilization costs data were collected. The performance metrics related to construction schedule growth and construction intensity were developed in order to test the research hypotheses: mobilization costs will increase the schedule performance of highway projects. The data were also divided into two groups based on project cost and analyzed to check whether the mobilization costs impact the schedule performance of these highway projects. Spearman's correlation test was conducted to determine the correlation between dependent and independent variables. In addition, a Mann–Whitney test was conducted to determine the difference in medians of construction schedule growth and the construction intensity of these two groups of projects.

One major study finding was that there was no strong linear correlation between the mobilization cost percentage and the construction schedule growth and construction intensity of highway projects. However, the study found the projects that have 9% or more mobilization costs had significantly better schedule growth compared to the projects that have less than 9% mobilization costs. When data were analyzed based on the project size, it was found that this pattern was seen only in large projects costing equal to or more than $5 million.

This study's findings have very crucial practical implications to state DOTs contract engineers. This study shows that the highway contract engineers need to provide the right amount of mobilization costs to complete their projects on and before schedule. If the correct amount of mobilization costs is not provided to the contractors, the impact of these mobilization costs on reducing the schedule growth will be negligible. The findings of this study will assist public agency decision makers to complete their projects on or before time by including the mobilization costs provision in the contract. The state DOTs can improve their schedule performance by providing enough financial help to the contractors so that they can improve their cash flows and complete projects successfully within the given timeframe.

This paper contributes to the existing body of knowledge by validating the impact of mobilization costs on the schedule performance of highway projects. There has been no empirical study conducted prior to this to identify the role of mobilization costs on reducing the schedule growth of highway projects.

Proper identification, allocation, and pricing of risks are critical to effective procurement and project delivery, particularly when contracts specify the intended performance instead of how the work is to be performed. This paper presents an overview of the sources of project risks when performance specifications are used for highway infrastructure procurement. The findings are based on a comprehensive literature review and interviews with subject-matter experts involved in developing performance specifications for highway infrastructure. The authors conclude that wider use of performance specifications in U.S. highway infrastructure construction requires a fundamental reassessment of risk allocation and pricing. Highway agencies and the contractors need to realign their respective organizational capabilities with the goal of using performance specifications as a facilitator of innovation, a goal that remains elusive after decades of applied research.

Proper identification, allocation, and pricing of risks are critical to effective procurement and project delivery, particularly when contracts specify the intended performance instead of how the work is to be performed. This paper presents an overview of the sources of project risks when performance specifications are used for highway infrastructure procurement. The findings are based on a comprehensive literature review and interviews with subject-matter experts involved in developing performance specifications for highway infrastructure. The authors conclude that wider use of performance specifications in U.S. highway infrastructure construction requires a fundamental reassessment of risk allocation and pricing. Highway agencies and the contractors need to realign their respective organizational capabilities with the goal of using performance specifications as a facilitator of innovation, a goal that remains elusive after decades of applied research.

This study aims to map out contractors' thoughts on construction-related environmental recovery as an excuse for deliberately carrying on unsustainable construction.

A typical highway construction project in China was investigated. Textual materials were collected through semistructured interviews. Content analysis was conducted to derive qualitative data from the textual materials.

The research findings reveal a trend of environmental recovery associated with construction activities. It is found that contractors utilize this trend to maintain unsustainable construction. Furthermore, the effects of environmental recovery equip local governments with a tolerance for environmental degradation, and the environmental tolerance allows contractors to continue unsustainable construction without being discovered.

This paper presents an environmental recovery-based perspective on unsustainable construction and sheds some light on the promotion of sustainable construction.

This study aims to analyze the interaction and key factors within the network of factors influencing the success of green highway projects.

Through literature review and interviews with experienced project managers, this study identified 33 influencing factors from the perspectives of stakeholders and life cycle. The interaction between these influencing factors was determined by surveying different experts, most of whom have participated in green highway projects in China. Then, social network analysis (SNA) was used to explore the impact and control ability of different factors.

According to the prioritization of these factors, the results showed that some key factors were identified, especially incremental cost, lack of standards and regulations, development of innovative technologies and materials, public awareness and environmental protection behavior. Finally, some meaningful suggestions were put forward for different influencing factors of green highway projects.

While the key influencing factors of the green highway projects have been identified by considering the interrelationships between different factors, the specific influencing paths and levels of different factors are not analyzed, more studies and methods should be conducted on this area in the future.

This finding of factors influencing the success of green highway projects which is useful for managers to overcome various obstacles encountered in similar projects. Moreover, considering the interaction among the influencing factors enables managers to make systematic and efficient decisions.

Developing green highways have been perceived as a major innovation to help achieve the synergy of environmental protection, economic development and social responsibility. Studying the key factors influencing the success of green highway projects and putting forward targeted suggestions are crucial for promoting the environmental protection transformation of highway construction.

Compared with most studies on the identification of key influencing factors of construction projects, this research emphasized the interaction between different factors within the system in the analysis process. The findings could provide useful references to promote the successful implementation of green highway projects.