In the early stages of a Construction project, the reliability and accuracy of conceptual cost estimates are major concerns for clients and cost engineers. Previous studies applied scoring methods and established common rules or mathematical methods to assess the quality of cost estimates. However, those approaches have some limitations in adapting to real-world projects or require understanding of sophisticated statistical techniques. We propose a Conceptual cost Estimate Reliability Index (CCERI), a simple, easy-to-use, and easy-to-understand tool that incorporates weights for 20 factors influencing the quality of conceptual cost estimates. The weights were obtained by eliciting experts’ experience and knowledge. cost data from 71 building projects were used in the analysis and validation of the CCERI. The analysis reveals that a conceptual cost estimate with a CCERI score of less than 3000 has a high probability of exceeding 10% error, and such conceptual cost estimates are unlikely to be reliable. With the CCERI score, a decision maker or a client can recognize the reliability of the conceptual cost estimates and the score can thus support decision making using conceptual cost estimates. In addition, with the CCERI and the relative importance weights of factors affecting the conceptual cost estimates, the estimator can find ways to modify a conceptual cost estimate and reestimate it. These alternatives can decrease the risk in the conceptual estimated cost and assist in the successful management of a Construction project.

cost overruns and delay are common issues in the Construction industry of developing and developed countries. In this article, compared with Construction projects in other developing countries, the common causes of the cost overruns and delay in delivering municipal Construction projects are discussed. This case study considers municipal Construction projects in the city of Karaj, as one of the fastest developing cities in Iran. To meet the objectives of this research, 72 different types of urban roads and building projects are considered. This study shows that small-budget and short-term municipal projects, generally, experience higher cost and time performance. This paper contributes to the Construction project management body of knowledge by a comprehensive analysis of cost overruns and delays in delivering municipal Construction projects in developing countries. The findings of this study may be used by municipalities, for the realistic strategic planning of their Construction projects, especially in developing countries.

This paper presents a simple methodology for cost estimation of a near optimal heat exchanger network, which comprises mixed materials of Construction. In traditional pinch technology and mathematical programming it is usually assumed that all heat exchangers in a network obey a single cost model. This implies that all heat exchangers in a network are of the same type and use the same materials of Construction (an assumption that is unwarranted). The method introduced in this article enables the designer to decomposes the total cost of a heat exchanger into two elements, namely cost of the tubes and cost of the shell, thereby predict a more reliable cost for the network. By subsequent use of the binary variables and evaluation of the physical conditions of the streams, one can assign the streams to pass either through shell or tubes. Whereby, shell and tubes can be of different materials and therefore different cost models can be applied. Another advantage of the approach is that the pressure drop in each side of the exchanger (shell or tubes) can be assessed leading to more accurate evaluation of corresponding heat transfer coefficient for each individual stream. Finally an objective function (total cost) can be defined based on mixed materials of Construction and different values of heat transfer coefficients. The proposed model has been utilized in three different case studies and the results are compared with those of commercially available software (SUPERTARGET). The comparison shows reductions of more than 17% and 14% in total annual costs in the two cases, and 2.5% reduction in third, confirming the fact that more accurate evaluation of heat transfer coefficient for each individual stream can lead to better network design.