Savaş Bayram

Comparison of multi layer perceptron (MLP) and radial basis function (RBF) for construction cost estimation: the case of Turkey

AbstractIn Turkey, for the preliminary construction cost estimation, a notice, which is updated and published annually by Turkish Ministry of the Environment and Urbanism, known as “unit area cost method” (UACM) is generally employed. However, its known that the costs obtained through this method in which only construction area is taken into consideration have significant differences from actual costs. The aim of this study is to compare the cost estimations obtained through “multi layer perceptron” (MLP) and “radial basis function” (RBF), which are commonly used artificial neural network (ANN) methods. The results of MLP and RBF were also compared with the results of UACM and the validity of UACM was interpreted. Dataobtained from 232 public construction projects, which completed between 2003 and 2011 in different regions of Turkey, were reviewed. Consequently, estimated costs obtained from RBF were found to be higher than the actual costs with a 0.28% variance, while the estimated costs obtained from M...

Cost forecasting using RCF: a case study for planning public building projects costs in Turkey

ABSTRACT Many construction projects are perceived to perform badly since the majority of them suffer cost overruns. This paper analyses cost estimates produced by two most commonly used estimation methods for building projects in Turkey, namely unit area cost (UAC) and unit price analysis (UPA). It also investigates whether reference class forecasting (RCF) method can be used to provide the client with more certainty in the final project cost forecasts compared to those two methods. Data from 369 public building projects in Turkey were collected and cost overruns were analysed. Part of the data representing 14% of the projects were randomly selected and used as control group for testing the reliability of the forecasts produced using RCF. The results have shown the estimates of the final project cost produced using the UAC and UPA methods in Turkey are either too pessimistic or optimistic. The results have also shown that it is possible to use the reference class as a basis to produce a reasonably accurate prediction of the actual cost of a project in a similar class for various levels of acceptable risks. This is achieved by adding uplifts/reductions to the estimates produced by the two traditional methods.

Application of reference class forecasting in Turkish public construction projects: contractor perspective

AbstractCost overrun in construction projects is an important problem that can have serious financial consequences. It also reduces the effectiveness of planning and decision making not only for the contractor but for all parties involved. The problem keeps occurring despite many attempts made over the years to improve cost estimation and forecasting methods. This paper focuses on analyzing cost overruns in Turkey and comparing the cost estimates produced using the traditional estimating method against cost forecasts produced using the reference class forecasting (RCF) method. RCF is used to predict the final cost of a project predicated on actual cost outcomes of accomplished similar projects in the same reference class. RCF has been so far used to address estimation bias in early project development before design is completed and before all risks are accounted for to help a client to produce a more realistic forecast of the final project cost. In this paper, however, it is used to produce a forecast of ...

LEGISLATION OF CONSTRUCTION WASTE CONCEPT AND A CASE STUDY AT A READY MIXED CONCRETE PLANT

Supply of the facilities like clean water, shelters, transportation is fundamental construction activities which are required for the survival of the humankind. Efficient and effective use of required resources and waste management activities are also the responsibility of the authorities like; contractors, subcontractors who undertake these activities and application of resource and waste management approaches during construction activities has important environmental impacts. Thus, European Union (EU) legislations and applications in Turkey are investigated in this study together with the general knowledge about waste concept and waste management in construction. Additionally, waste management procedures of a ready-mixed concrete plant in Kayseri, was investigated as a case study.