Road tunnel construction is subject to underground uncertainties and risks, and as such it is difficult to predict the final construction cost, especially at the conception phase where issues are evaluated and important design decisions are made. A system assisting in the early cost estimation of road tunnels would therefore be of great value as it would allow the quick costing of alternative and more economical solutions. The development of such an early cost estimation system is discussed in this paper. First, the basic parameters (geological, geometrical, and work quantities-related) affecting temporary and permanent support and final construction cost are determined. After that, appropriate real-world data derived from the analysis of 33 twin tunnels of 46 km total length constructed for the Egnatia Motorway in northern Greece from 1998 to 2004 and related to work quantities is collected and normalized. Appropriate price lists are then applied to calculate the costs; subsequently, cost-estimat...

Cost–benefit analysis (CBA) is considered an effective evaluation method for fostering optimal decision making and ranking of road infrastructures over decades. This paper introduces a comprehensive systematic literature review focusing on CBA’s methodological perspective for identifying its current modelling approaches and scrutinizing their key features and encompassed tools. Fifty-six relevant studies were extracted from Web of Science, Scopus and Google Scholar from 2005 until 2020. Initially, the bibliometric analysis presents an overall illustration of the most significant CBA concepts. The descriptive statistics determined eight distinct modelling categories used for CBA implementation, each encompassing three different modelling approaches for capturing the data risk assessment (deterministic or probabilistic), CBA’s parameters interactive behavior (static or dynamic) and the considered economies (microeconomic or macroeconomic). In-depth content analysis led to the interpretation of the current status of extant models and the identification of three main knowledge gaps: the absence of the CBA’s inputs updating into a probabilistic environment, the deficiency of a dynamic interdependent framework and the necessity of homogenous cost datasets for road projects. Future research directions and a conceptual framework for modelling CBA into a microeconomic, probabilistic and dynamic environment are proposed providing decision-makers with new avenues for more reliable CBA modelling.

The term “Project Management Practice” is construed in several ways. For this research, we comply with the project management use of tools and techniques on project’s time and cost (Crawford 2005 Crawford L . 2005. Senior management perceptions of project management competence. Int J Proj Manage. 23(1):7–16. [Crossref] , [Google Scholar] ; Olateju et al. 2011 Olateju OI , Abdul-Azeez IA , Alamutu SA . 2011. Project management practice in Nigerian public Sector – an empirical study. Aust J Bus Manage Res. 1(8):01–07. [Google Scholar] ; Abassi and Al-Mharmah 2000). Project scheduling still is based on the traditional methods of critical path method (CPM) and Program Evaluation and Review Technique for the majority of contractors and public institutions. The aim of this work is to critically highlight the reasons under which the use of the Critical Chain Project Management (CCPM) is indispensable for scheduling and monitoring public works by public institutions in Greece. In particular, the conclusions of this study are very important for public institutions that don’t implement modern project management practices, tools and techniques. The methodology is exemplified by the analysis of 27 infrastructure projects. The contracts include 300 km of motorway, 46 km of road tunnels and 20 km of bridges constructed for the Egnatia Motorway in Northern Greece from 2002 to 2012. The results confirms that CCPM can perform better than the traditional method of CPM by achieving less construction time combined with accurate resource levelling in the early stages. The aforementioned procedure results in reduced indirect costs due to project's time reduction and reduced direct costs due to better resource allocation (ensuring “on time” availability of resources). As a conclusion, better financial planning is ensured for both the contracting parties i.e. the contractors and the public institutions. It should be noted that in literature the case studies are rare with very small sample size.

The area of dynamic planning of construction sites is unexplored. Although there is a large amount of scientific interest in the literature in dynamic planning of construction site layouts, with different methodologies developed, studies on construction site relocation do not exist. The purpose of this study is to cover this gap in the literature and contribute to the body of knowledge by presenting for the first time a dynamic planning of a construction site and its importance in linear construction projects and to validate this methodology through real case studies. The decisive variables that determine the appropriate site locations and the costs that arise from these choices are analyzed. The choice that maximizes the production rate of the construction site and thus minimizes the costs is further investigated. An algorithm has also been developed that estimates the cost of transportation of the equipment used in the project and thus enables the investigation of the “ideal” location that minimizes this cost. The “ideal” site location is examined according to the time schedule of the project at time intervals that are determined by the work progress. The optimization algorithm aims to minimize the cost that derives from non-productive activities. The validity of the proposed model is tested in four motorway projects. A sensitivity analysis concerning different sequences in the construction methods reveals remarkable changes in cost fluctuations depending on project size. The outcomes show that for the second, third, and fourth projects, dynamic planning is demanded, and the profit gained ranges from 1 to 1.5% of total budget cost. Financing expenses could be covered by this profit. The case studies presented are derived from linear infrastructure projects that are more sensitive to this approach because of their size and their budget that both affect the results.