Cost Estimating

This article presents the results of a study of the accuracy of cost estimates in public building projects in Nigeria. Data were collected from a sample of 40 completed building projects with initial cost values of between N3.00m – N187.19m. A questionnaire survey of construction professionals was also undertaken in which the respondents were asked to indicate their opinions on the causes of inaccurate cost estimate in public work projects. Seventy five (75) survey questionnaires were distributed and fifty three (53) of them were returned completed. Based on the analysis of the data collected, it was found that, public building projects exceed their initial estimates by an average value of 5.16%. Furthermore, 65.0% of the projects considered have their estimated costs within the limits of ±5% of the actual costs. The survey revealed that, the main factors that influence the accuracy of cost estimates of public building projects are improper planning, non compliance with condition of contract, incompetence on the part of the contractors, lack of understanding of project requirements by the estimator and insufficient information related to the project before execution. To improve on the accuracy of cost estimates, it is recommended that both the client and the contactor should make adequate planning in terms of the resources required for the execution of the projects at early stage, prior to the commencement of the work Significance: Cost estimating is an important aspect of construction project. The performance and overall project success are often measured by how well the actual cost compares to estimated cost. In other words, the success or failure of a project is dependent on several estimates throughout the course of the project. Therefore it is imperative to evaluate the accuracy of cost estimates in public projects and propose appropriate measures that would help reduce inaccurate estimates.

Construction cost management is the most important function for project success, and the construction project performance is generally expressed in terms of cost and its variance from the budget. However, it has not been effectively used due to the presence of a large quantity of data with many complex interrelationships. Construction firms, being project based organizations, have to develop their project management capacity in order to accomplish firm and project objectives successfully. Hence contractors need to focus on project cost management process. The study presents the limitations, drawbacks and shortcomings of each project cost management functions related to current practices of domestic contractors, which need to be improved for achieving the predefined project objectives and the profitability of contractors along with the proposed improvement recommendations, through critical literature review.

Construction cost estimation importance can be better defined with its application in Bid and project management system. Cost estimation in project management is the procedure to predict the cost and additional funds which are essential to complete a project within a specified range. The project site is never finalized until the project feasibility report has been done. At that point, professional construction estimators calculate all resources which are required for the project including the total budget of the project. Generally, the construction cost estimating is categorized in 5 different levels which are based on one of AACE's recommended practices, shown below.

A strategy for adaptive control and energetic optimization of aerobic fermentors was implemented, with both air flow and agitation speed as manipulated variables. This strategy is separable in its components: control, optimization, estimation. We optimized parameter’s estimation (from the usual KLa correlation) using sinusoidal excitation of air flow and agitation speed. We have implemented parameter’s estimation trough recursive least squares algorithm with forgetting factor. We carried separate essays on control, optimization and estimation algorithms. We carried our essays using an original computational simulation environment, with noise and delay generating facilities for data sampling and filtering.

Our results show the convergence and robustness of the estimation algorithm used, improved with use of both forgetting factor and KLa dead-band facilities. Control algorithm used in our work compares favorably with PID using the integrated area criteria for deviation between oxygen molarity and critical molarity (set point). Optimization algorithm clearly reduces energetic consumption, respecting critical molarity. Integration of control, optimization and adaptive algorithms was implemented, but future work is needed for stability. Methods were defined and implemented for stability improvement. We have implemented data acquisition and computer manipulation of air flow and agitation speed for actual fermentors.

A large proportion of the Nigerian government's expenditure on capital project delivery involves civil engineering works, with greater emphasis on roadworks to create access for the conduct of economic activities by citizens. Most of the works of this scope awarded to indigenous contractors involve large volumes of cut and fill earthworks. Accurately estimating the cost of earthworks for most indigenous contractors is an arduous task owing to the stochastic nature of the input variables. This paper, therefore, seeks to identify key factors affecting the accuracy of earthwork cost estimates in civil engineering projects in Nigeria and to determine the effects of the factors on the level of accuracy of the estimates. The methodology of study involved a structured questionnaire survey of 78 indigenous contractors operating in the nation's SouthEast and South-South geopolitical zones. Five (5) major factors affecting the accuracy of earthwork cost estimates (contract requirements and equipment, estimator-related, microeconomic, nature of site and site-level management) were obtained by factor analysis using varimax rotation. However, based on ANOVA test of difference, the study found that the differing levels of accuracy of earthwork cost estimates are caused by contract requirements and equipment, estimator-related and microeconomic factors. Thus, the consideration of these three factors leads to higher levels of accuracy of earthwork cost estimates in civil works. The study recommends that indigenous contractors' earthwork cost estimators for civil works should give more attention to contract requirements and equipment, estimator-related, and microeconomic factors for improved accuracy of their estimates.

One of the major challenges for software, nowadays, is software cost estimation. It refers to estimating the cost of all activities including software development, design, supervision, maintenance and so on. Accurate cost-estimation of software projects optimizes the internal and external processes, staff works, efforts and the overheads to be coordinated with one another. In the management software projects, estimation must be taken into account so that reduces costs, timing and possible risks to avoid project failure. In this paper, a decision- support system using a combination of multi-layer artificial neural network and decision tree is proposed to estimate the cost of software projects. In the model included into the proposed system, normalizing factors, which is vital in evaluating efforts and costs estimation, is carried out using C4.5
decision tree. Moreover, testing and training factors are done by multi-layer artificial neural network and the most optimal values are allocated to them. The experimental results and evaluations on Dataset NASA60 show that the proposed system has less amount of the total average relative error compared with COCOMO model.

Abstract Reinforced concrete multi-story buildings are commonly used in residential, commercial, and administrative projects; therefore, selecting the optimum structural system with minimum cost is the top priority of the structural designer. Although earlier researches intensively studied this issue, it is still not completely covered. This research aims to introduce recommendations for the optimum gravity and lateral systems for a multi-story reinforced concrete (RC) building from a perspective of direct cost. In order to achieve that goal, a parametric study was carried out using 72 RC buildings with several stories ranged between 5 and 50 floors, and grid spacing ranged between 6.0 and 12.0 m. Four floor systems were considered, solid, 2 ways ribbed, waffle, and flat slabs. Also, three lateral loads resisting systems were considered which are intermediate moment resisting frames, shear walls, and a dual system. The study covered the low, medium and high rise buildings. The results indicated that the dual system is the most suitable system for medium and high rise buildings with combination with solid slabs for short spans and ribbed slabs for medium and long spans. On the other hand, frame with solid slabs is the optimum for low rise with short spans and shear wall with the flat slab is the optimum for low rise with medium and long spans.

Terminal users face a variety of costs associated with the container terminal and those that are harder to quantify should not be ignored for they might represent a larger component of the overall costs associated with using a particular terminal. Similarly, the competitive ...

The objective of this study is to develop early cost estimating models for road construction projects using multiple regression techniques, based on 131 sets of data collected in the West Bank in Palestine. As the cost estimates are required at early stages of a project, considerations were given to the fact that the input data for the required regression model could be easily extracted from sketches or scope definition of the project. 11 regression models are developed to estimate the total cost of road construction project in US dollar; 5 of them include bid quantities as input variables and 6 include road length and road width. The coefficient of determination r2 for the developed models is ranging from 0.92 to 0.98 which indicate that the predicted values from a forecast models fit with the real-life data. The values of the mean absolute percentage error (MAPE) of the developed regression models are ranging from 13% to 31%, the results compare favorably with past researches whic...

One of the major challenges for software, nowadays, is software cost estimation. It refers to estimating the cost of all activities including software development, design, supervision, maintenance and so on. Accurate cost-estimation of software projects optimizes the internal and external processes, staff works, efforts and the overheads to be coordinated with one another. In the management software projects, estimation must be taken into account so that reduces costs, timing and possible risks to avoid project failure. In this paper, a decision- support system using a combination of multi-layer artificial neural network and decision tree is proposed to estimate the cost of software projects. In the model included into the proposed system, normalizing factors, which is vital in evaluating efforts and costs estimation, is carried out using C4.5 decision tree. Moreover, testing and training factors are done by multi-layer artificial neural network and the most optimal values are alloc...

Construction cost management is the most important function for project success, and the construction project performance is generally expressed in terms of cost and its variance from the budget. However, it has not been effectively used due to the presence of a large quantity of data with many complex interrelationships. Construction firms, being project based organizations, have to develop their project management capacity in order to accomplish firm and project objectives successfully. Hence contractors need to focus on project cost management process. The study presents the limitations, drawbacks and shortcomings of each project cost management functions related to current practices of domestic contractors, which need to be improved for achieving the predefined project objectives and the profitability of contractors along with the proposed improvement recommendations, through critical literature review.

In this paper we are presenting our research findings on how effective neural networks are at forecasting and estimating preliminary project costs. We have shown that neural networks completely outperform traditional techniques in such tasks. In exploring nonlinear techniques almost all of the current research involves neural network techniques, especially multilayer perceptron (MLP) models and other statistical techniques and few authors have considered radial basis function neural network (RBF NN) models in their research. For this purpose we have developed RBF NN models to represent nonlinear static and dynamic processes and compared their performance with traditional methods. The traditional methods applied in this paper are multiple linear regression (MLR) and autoregressive moving average models with eXogenous input (ARMAX). The performance of these and RBF neural network and traditional models is tested on common data sets and their results are presented.

Le modifiche apportate al processo esecutivo dalla Legge 132 del 6 agosto 2015, con la possibilità di un abbattimento del 25% sul prezzo base d’asta ed equivalente ribasso in caso di asta deserta, portano a dover rivedere il concetto di valore di recupero giudiziale di un immobile, che non potrà più coincidere con quello di vendita forzata. Infatti, non si tratta di una condizione di alienazione, dove una delle parti non è consenziente, ma di un meccanismo di vendita che in caso di asta deserta penalizza il prezzo basa d’asta di ¼ nel successivo tentativo.
Proviamo a definire un ipotesi per la stima del JMV

Contractors have to bid competitively for most of their work and at the same time deal with risks and uncertainties connected with bid submission. This paper examines the factors involved in tender pricing and how they relate to each others. From this, a conceptual model of contractors' pricing strategy is developed.

This paper presents the results of a 2012 life cycle cost (LCC) study of hybrid Reusable Booster Systems (RBS) conducted by NASA Kennedy Space Center (KSC) and the Air Force Research Laboratory (AFRL). The work included the creation of a new cost estimating model and an LCC analysis, building on past work where applicable, but emphasizing the integration of new approaches in life cycle cost estimation. Specifically, the inclusion of industry processes/practices and indirect costs were a new and significant part of the analysis. The focus of LCC estimation has traditionally been from the perspective of technology, design characteristics, and related factors such as reliability. Technology has informed the cost related support to decision makers interested in risk and budget insight. This traditional emphasis on technology occurs even though it is well established that complex aerospace systems costs are mostly about indirect costs, with likely only partial influence in these indirect costs being due to the more visible technology products. Organizational considerations, processes/practices, and indirect costs are traditionally derived (" wrapped ") only by relationship to tangible product characteristics. This traditional approach works well as long as it is understood that no significant changes, and by relation no significant improvements, are being pursued in the area of either the government acquisition or industry's indirect costs. In this sense then, most launch systems cost models ignore most costs. The alternative was implemented in this LCC study, whereby the approach considered technology and process/practices in balance, with as much detail for one as the other. This RBS LCC study has avoided point-designs, for now, instead emphasizing exploring the trade-space of potential technology advances joined with potential process/practice advances. Given the range of decisions, and all their combinations, it was necessary to create a model of the original model and use genetic algorithms to explore results. A strong business case occurs when viable paths are identified for an affordable up-front investment, and these paths can credibly achieve affordable, responsive operations, characterized by smaller direct touch labor efforts at the wing level from flight to flight. The results supporting this approach, its potential, and its conclusions are presented here.

The New York State Department of Transportation (NYSDOT) Consultant Management Bureau’s primary responsibilities are to negotiate staffing hours/resources with engineering design consultants, and to monitor the consultant's costs. Currently the Consultant Management Bureau uses knowledge of past and current projects as well as engineering judgment to estimate consultant costs. The proposed research will focus on several major issues: 1) the establishment of a central database that contains historic total project cost and staffing level data; 2) the development of a computer based estimating tool that employs the data from the historical database to provide more accurate and efficient estimates of consultant resources; 3) identifying major variables that affect the consultant's hours and developing predictive models, using multiple regression analysis as a method for developing the models. Only techniques that can easily be incorporated in an Excel spreadsheet will be conside...

... Because forming schedule manually is very costly and time consuming the scheduler cannot perform several schedule alternative to evaluate time integrated cost that indicate the timing of capital needs for the design decisions and construction methods selection. ...

Contractors have to bid competitively for most of their work and at the same time deal with risks and uncertainties connected with bid submission. This paper examines the factors involved in tender pricing and how they relate to each others. From this, a conceptual model of contractors' pricing strategy is developed.

Pre-tender cost estimating of office building projects requires extensive knowledge and expertise. Due to the lack of design information in the early design stages, it is extremely difficult for cost engineers or quantity surveyors to arrive at an accurate cost estimate. This paper presents the design and testing of a knowledge-based system that enables students to learn cost estimating of building projects in the conceptual design stages. The system, embedded with knowledge from experts, has been proved to be a very useful teaching and learning tool. © 2001 John Wiley & Sons, Inc. Comput Appl Eng Educ 9: 26–36, 2001

Ownership of the U.S. rail industry is divided between eight Class I railroads (those with more than $258.5 million in annual revenue) and about 550 regional and short-line railroads. The eight large railroads own about 70 percent of the 273 700 track-km (170,000 track-mi) and account for about 90 percent of industry revenues. The remaining 30 percent of track kilometers belongs to the regional and short-line railroads, which must operate and maintain them with 10 percent of industry revenues. U.S. railroads function as an integrated network; freight originating on a short-line railroad can be delivered anywhere in the United States, Canada, or Mexico. Equipment is freely interchanged, so the small railroads must handle the same heavy cars as the Class I railroads even though maximum freight car weights have increased in recent years, with cars of 129 844 kg (286,000 lb) becoming common. Many of the smaller railroads own trackage that had been branchlines belonging to the larger com...

... 1992; Isom 1995). Weather impact was also reported to be one of the main factors causing delays and cost overruns on other types of construction projects (Baldwin et al. 1971; Koehn and Meilhede 1981; Laufer and Cohenca 1990; Moselhi et al. 1997; Fadaka 1999). ...

Contract incentives have traditionally been used as a means of aligning the goals of the contracting agency with those of the contractor. One area in which contract incentives are used is highway construction and refurbishing. The use of incentives and disincentives (I ...

Abstract Reinforced concrete multi-story buildings are commonly used in residential, commercial, and administrative projects; therefore, selecting the optimum structural system with minimum cost is the top priority of the structural designer. Although earlier researches intensively studied this issue, it is still not completely covered. This research aims to introduce recommendations for the optimum gravity and lateral systems for a multi-story reinforced concrete (RC) building from a perspective of direct cost. In order to achieve that goal, a parametric study was carried out using 72 RC buildings with several stories ranged between 5 and 50 floors, and grid spacing ranged between 6.0 and 12.0 m. Four floor systems were considered, solid, 2 ways ribbed, waffle, and flat slabs. Also, three lateral loads resisting systems were considered which are intermediate moment resisting frames, shear walls, and a dual system. The study covered the low, medium and high rise buildings. The results indicated that the dual system is the most suitable system for medium and high rise buildings with combination with solid slabs for short spans and ribbed slabs for medium and long spans. On the other hand, frame with solid slabs is the optimum for low rise with short spans and shear wall with the flat slab is the optimum for low rise with medium and long spans.

Abstract: The objective of this paper is to analyze the effects that vehicle volumes and lane closure lengths have on road user costs (RUCs) in rural freeway work zones. A methodology has been developed in this paper for estimating RUCs for a rural four lane freeway under ...

Estimation is the first step in the project development process. Information technology provides an efficient platform for estimators to obtain quotations and specifications for their bid estimates. However, in practice, project overhead estimation relies heavily on the professional judgement and intuition of the estimators. This reduces the overall accuracy and reliability of the bid and a better understanding of the

Reinforced concrete multi-story buildings are commonly used in residential, commercial, and administrative projects; therefore, selecting the optimum structural system with minimum cost is the top priority of the structural designer. Although earlier researches intensively studied this issue, it is still not completely covered. This research aims to introduce recommendations for the optimum gravity and lateral systems for a multi-story reinforced concrete (RC) building from a perspective of direct cost. In order to achieve that goal, a parametric study was carried out using 72 RC buildings with several stories ranged between 5 and 50 floors, and grid spacing ranged between 6.0 and 12.0 m. Four floor systems were considered, solid, 2 ways ribbed, waffle, and flat slabs. Also, three lateral loads resisting systems were considered which are intermediate moment resisting frames, shear walls, and a dual system. The study covered the low, medium and high rise buildings. The results indicated that the dual system is the most suitable system for medium and high rise buildings with combination with solid slabs for short spans and ribbed slabs for medium and long spans. On the other hand, frame with solid slabs is the optimum for low rise with short spans and shear wall with the flat slab is the optimum for low rise with medium and long spans.