John-Paris Pantouvakis

Fuzzy Repetitive Scheduling Method for Projects with Repeating Activities

In projects with repeating activities (such as multistory buildings, highways, or pipelines consisting of reiterating identical or similar units) and in which the activity unit production rates are characterized by uncertainty or imprecision, fuzzy set theory and the well-established repetitive scheduling method (RSM) can be combined to ensure uninterrupted usage of resources between similar activities in different units. The reason for this approach is that in practice the application of RSM may be hindered by several considerations, for example, repetitive units may be slightly different from each other, the performance of construction crews may vary, and there may be complex resource matching and sharing between activities and work sites. The proposed methodology is termed fuzzy repetitive scheduling method (F-RSM), and it requires a generalization of RSM in which schedules are represented by two- or three-dimensional graphs and whereby the concepts of a control segment and the controlling sequence area are introduced. The resulting methodology addressing the original RSM scheduling problem is presented in this paper.

SEMANTIC: Smart EarthMoving ANalysis and estimation of Cost

Earthmoving is an important activity in almost all civil engineering projects; consequently there is always the need to improve existing earthmoving operational and managerial techniques. This paper presents an integrated computer aided system for the analysis and cost estimation of various earthmoving tasks. The fully operational SEMANTIC consists of four modules. The smart module, exploiting artificial intelligence techniques, advises the user on the selection of the appropriate type of machinery for the task in question. The data management module takes advantage of extended databases containing information on types of soil and technical and cost parameters for a large number of equipment models. Based on descriptive information provided by the user, it suggests values for the many parameters required and facilitates enormously the preparation of input for analytical computations. The output and cost estimation module comprises algorithms for various earthmoving tasks and related machine types or combi...

Road tunnel early cost estimates using multiple regression analysis

Among construction projects, the risk in the production of road tunnels is particularly high due to the inherit uncertainties of the underground conditions. Equally, tunnel costs are considerably higher as compared to those of normal surface roads. As published literature on early cost estimating tools for road tunnels is scarce, projects sponsors, decision makers and engineers lack reliable tools, especially during the important early conceptual and preliminary design stages, to establish the project budget. The problem is addressed in this paper aiming at developing early parametric estimating models for road tunnels based upon the application of multiple regression analysis on real-world constructed projects. Thirty-three road tunnels totaling forty-six Km in single bore length constructed for the Egnatia motorway in northern Greece were analyzed for this purpose. To do so, data related to the encountered geotechnical parameters of rock masses and the corresponding quantities of primary and permanent support were gathered and put into a database. This database coupled with statistical techniques was subsequently used to establish the correlation between geotechnical and construction parameters. Following this stage, tests were performed to validate the correlations produced. The analysis highlighted the most important parameters affecting construction cost. It can be corroborated therefore that the approach employed in this work is valid for heavy construction projects and, furthermore, contributes to the long lasting problem of obtaining valid data to produce reliable early cost estimates for road tunnel construction.

A compromise programming model for site selection of borrow pits

Road fill construction requires soil for filling low areas; this soil is obtained from temporary mineral workings known as ‘borrow pits’ (BP). Between a number of possible BPs, the appropriate site should be selected based upon conflicting econo‐technical and environmental criteria aiming at achieving optimal BP performance while minimizing the adverse impacts to human and natural resources. For solving this problem a model for BP selection has been developed by this research using compromise programming (CP). The model incorporates a hierarchical structure integrating criteria and sub‐criteria whose relative importance is set by the decision makers. Possible alternative BP sites are subsequently assessed on all these sub‐criteria. Based upon this analysis, the model determines the distance of each of the possible alternatives from the utopia (ideal) point; the option with the minimum distance is considered the best compromise. The relevant concepts are exemplified through the presentation of a case study concerning the BP site selection for an Egnatia Motorway section in northwest Greece. The main conclusion that can be drawn from this work is that the CP approach is appropriate and valid for BP selection and, furthermore, it may also be used for other multiple objective construction‐related site selection problems.

A practical approach to resource - constrained project scheduling

In this paper a solution approach is discussed for managing projects with resource constraints. For this purpose a heuristic method is developed based on traditional CPM scheduling calculations and leveling algorithms. The method can be applied using normal scheduling software such as P3 and MS project, and as such, it is of value to practitioners. An illustrative example is also presented herein to exemplify the concepts. The problem solved has importance and direct application to the management of a wide variety of project-structured efforts with prevailing resource constraints.

A Computer-Aided Conceptual Cost Estimating System for Pre-Stressed Concrete Road Bridges

The need for an environmentally friendly design of modern motorways increases the construction of bridges, which has exhibited substantial overruns above estimated costs. Therefore, easy to use, inexpensive and accurate methods for conceptual cost estimating are needed. This paper presents a computer-aided cost estimating system for pre-stressed concrete road bridges that provides estimates of the material quantities and cost of all bridge elements. It relies on a database incorporating actual data collected from recently constructed bridges and exploits material estimating models developed with statistical analysis. Different configurations are devised from short to long-span bridges, accounting for the major deck construction methods and foundation systems. The system can be easily used to provide different cost estimates to the owner, designer and contractor during the projects early stages. By allowing reliable cost estimates in a short time, the proposed computer-aided system represents a useful decision making tool.

Simulation-Based and Statistical Analysis of the Learning Effect in Floating Caisson Construction Operations

AbstractThe learning curve theory is implemented for the assessment and prediction of performance in repetitive and complex construction operations. The purpose of this study is to explore the applicability of learning curve concepts for the fabrication of floating caissons, a construction activity that has not been adequately explored in the published literature. Although standard statistics and simulation methods have been used, a direct comparison of the produced results, along with their emerging inferences, is attempted for the first time. In addition, simulation modeling is used to predict future performance within the learning curve paradigm. An extended version of an existing simulation platform (CaissonSim) is used to execute the computations. A straight-line model is applied to quantify the improvements in productivity and the dynamically changing learning rates. A comparative analysis of the results has shown that both the statistical and simulation-based approaches have yielded satisfactory re...

An Integrated Information System for Monitoring Construction Works

There is a global tendency towards implementing centralized project monitoring with the use of advanced information systems in large projects. This trend is mandated by issues such as the geographical dispersion of projects, the number of contractors and the total amount of works. In this respect, the integrated information system that has been utilized to monitor the construction works of the Egnatia Motorway project in Greece is presented. Reference is made to the software, hardware, information technology architecture, quality procedures and personnel training for the successful implementation of the system. Special mention is made to the data structures that are utilised (enterprise project structure, organizational breakdown structure, resource breakdown structure, and work breakdown structure). In addition, comments are made from the experiences drawn from the implementation of the system. Overall, it is concluded that the integrated system constitutes a central focal point for corporate scheduling and cost control.

Investigation of earthmoving trucks deterioration using Discriminant Analysis

Earthmoving equipment has a determinant role in the successful realisation of most civil engineering projects. However, it may suffer significant downtime due to the continuous and intense use in harsh working conditions. This downtime may be associated with certain deterioration parameters, which if known, would allow more accurate estimations to be made. For this purpose, the data sets from two large Greek construction companies containing the characteristics of 126 earthmoving trucks (capacity, age, kilometres travelled to date, maintenance class and condition level) have been analysed using discriminant analysis. The analysis allows for the assessment of the connection of each characteristic with the condition level of the sample trucks and also leads to rules that can be used for the prediction of the condition level of other trucks.

A Process for the Estimation of the Duration of Activities in Fuzzy Project Scheduling

In dealing with uncertainty and imprecision Fuzzy Project Scheduling (FPS) has been presented as an alternative to well established traditional scheduling methods. The aim of this paper is to propose a process for the estimation of the duration of activities that are to be used in a FPS system. Initially, the sources of uncertainty are distinguished into the project and activity level. Then, the work focuses primarily on the calculation of the duration of activities based on the productivity of resources and the fuzzy parameters that define it. Thereafter, a specific example is presented from earthworks in a motorway project. Finally, the estimated duration can be adjusted based on the perceived risks at the project level. Overall, the paper presents a means for encoding a project managers perception of uncertainty in the duration of activities that are to be used in FPS.