Application of Delphi method in selection of procurement systems for construction projects

A number of procurement selection systems have been developed over the last decade. The use of multi-attribute decision analysis has been considered the foremost technique for examining client needs and the weightings of preferences from experts for each procurement system in the most objective way available. However, the major difficulty of these selection models lies in the lack of consensus among the experts on the utility factor of the selection criteria. To overcome these deficiencies, a Delphi technique was adopted to develop a multi-attribute model. Four rounds of Delphi surveys were conducted. A statistically significant consensus on the weighting of the utility factors for each procurement system was obtained from eight experts. The results vividly reveal that the Delphi method is a powerful and appropriate technique for deriving objective opinions in a rather subjective area such as the multi-attribute model for the selection of procurement system.     

Final contractor selection using the analytical hierarchy process

Some contractor selection methods currently in existence are criticized as incomplete and biased, and lacking consideration in terms of the contractor's ability to achieve simultaneously, time, cost, quality and safety standards. This research examines an alternative contractor selection model called the analytical hierarchy process (AHP), which will help construction clients to identify contractors with the best potential to deliver satisfactory outcomes in a final contractor selection process which is not based simply on the lowest bid. The AHP comprises three parts: hierarchic structure, prioritization procedure, and calculation of results. This model is tested by a hypothetical scenario where three contractor candidates are evaluated. The criteria used for contractor selection in the model have been identified, and the significance of each criterion has been arrived at by conducting a questionnaire survey in public organizations in Hong Kong. Comparisons are made by ranking the aggregate scores of each candidate with regard to their performance against each of the criteria, and the candidate associated with the highest scores is the best contractor on this occasion.     

高放核废物地质处置中工程屏障研究新进展

中国对该课题的研究始于1985年，但是长期以来未能引起足够的关注，相关研究项目也非常有限。近年来，随着中国经济的快速增长，能源短缺问题越来越严重，发展和利用核能己作为一种主要的解决方案，因此核废物的安全处置则成为现实的重要课题。中国在利用膨润土作为工程隔绝材料方面的研究工作，主要限于选择合适的膨润土，而高庙子膨润士作为最终选择的缓冲材料，其基本物理-化学特性已得到确定，但有关热-水-力耦合的试验尚未开展，相关课题的研究也尚需努力。鉴于国际上已对多种其他备选膨润土进行过大量研究，有关成果可望用于指导即将在中国进行的高庙子膨润土试验研究。此文的主要目的就是为中国核废物的地质处置研究提供一些有益的经验。首先，介绍使用基于膨润土的工程隔绝核废物地质处置方法，这一方法已为广泛接受；然后，介绍膨润土的选择标准，地质-化学特性、热-水-力性态（包括微观结构、宏观性态、接缝性态和数值分析），以及在放射性废物处置过程中产生的气体对工程隔绝层的影响等，通过不同实例来展示试验原理和主要结果；最后，对近期国内外研究成果和未来发展前景进行总结。     

Application of the analytic hierarchy process (AHP) in multi-criteria analysis of the selection of intelligent building systems

The availability of innumerable intelligent building (IB) products, and the current dearth of inclusive building component selection methods suggest that decision makers might be confronted with the quandary of forming a particular combination of components to suit the needs of a specific IB project. Despite this problem, few empirical studies have so far been undertaken to analyse the selection of the IB systems, and to identify key selection criteria for major IB systems. This study is designed to fill these research gaps. Two surveys: a general survey and the analytic hierarchy process (AHP) survey are proposed to achieve these objectives. The first general survey aims to collect general views from IB experts and practitioners to identify the perceived critical selection criteria, while the AHP survey was conducted to prioritize and assign the important weightings for the perceived criteria in the general survey. Results generally suggest that each IB system was determined by a disparate set of selection criteria with different weightings. ‘Work efficiency’ is perceived to be most important core selection criterion for various IB systems, while ‘user comfort’, ‘safety’ and ‘cost effectiveness’ are also considered to be significant. Two sub-criteria, ‘reliability’ and ‘operating and maintenance costs’, are regarded as prime factors to be considered in selecting IB systems. The current study contributes to the industry and IB research in at least two aspects. First, it widens the understanding of the selection criteria, as well as their degree of importance, of the IB systems. It also adopts a multi-criteria AHP approach which is a new method to analyse and select the building systems in IB. Further research would investigate the inter-relationship amongst the selection criteria.     

A multiple criteria evaluation of multi-family apartment block's maintenance contractors: I—Model for maintenance contractor evaluation and the determination of its selection criteria

The paper presents a model that describes the process of selecting dwelling maintenance contractors. The model is based on a multi-criteria evaluation of maintenance contractors, the determination of their utility level for the building's users and a bid price in negotiations that are made according to the results of the multiple criteria analysis. The proposed model could further be applied to plan dwelling maintenance operations. The criteria of maintenance contractor evaluation are selected by taking into consideration the interests and goals of the building's users as well as factors that influence the process of maintenance's efficiency. The correlation of the criteria characterizing maintenance contractors from various perspectives was determined.     

A total environmental risk assessment model for international hub airports

This paper presents a multi-criteria decision analysis for environmental risk assessment (ERA) with regard to avoiding and eliminating damages and loss under natural disasters in international airport projects. It starts from an assumption that the strategy of eliminating damages and losses under natural disasters is related to the location selection problem, and it is necessary to use the multi-criteria decision analysis for calculated decision-making support. The paper uses the analytic network process (ANP) to demonstrate one of its utility modes in decision-making support to location selection problems, which aims at an evaluation of different projects from different locations. A set of generic criteria for risk assessment at international projects was put forward to support ANP modelling, and it was due to the consideration of social, technical, economic, environmental and political (STEEP) criteria related to the built, social and natural (BSN) trinity environment of international airport projects. At the end, an experimental case study on three international hub airports in China is given to test the ANP model called ERA.Airport, and it is concluded that ANP can be effectively used for risk assessment in the specific utility mode. The ERA.Airport is a generic multi-criteria decision-making model and can be used across the world for accurate environmental risk assessment for international airports.     

Multi-criteria evaluation model for the selection of sustainable materials for building projects

Sustainable material selection represents an important strategy in building design. Current building materials selection methods fail to provide adequate solutions for two major issues: assessment based on sustainability principles, and the process of prioritizing and assigning weights to relevant assessment criteria. This paper proposes a building material selection model based on the fuzzy extended analytical hierarchy process (FEAHP) techniques, with a view to providing solutions for these two issues. Assessment criteria are identified based on sustainable triple bottom line (TBL) approach and the need of building stakeholders. A questionnaire survey of building experts is conducted to assess the relative importance of the criteria and aggregate them into six independent assessment factors. The FEAHP is used to prioritize and assign important weightings for the identified criteria. A numerical example, illustrating the implementation of the model is given. The proposed model provides guidance to building designers in selecting sustainable building materials.     

IntelliCranes: an integrated crane type and model selection system

The importance of the utilization of cranes in construction operations has resulted in the development of structured methods for crane selection. Most of these methods are for crane model selection and require the user to stipulate the type of crane to be used for the construction operation under consideration. Availability of a structured method for crane type selection will greatly benefit the overall crane selection process. This paper describes a prototype integrated crane selection tool, called IntelliCranes, designed to assist in both crane type and crane model selection. The key feature of IntelliCranes is the systematic incorporation of subjective and qualitative criteria in crane type and model selection.     

Multi-criteria evaluation model for the selection of architectural consultants

The selection of a competent architect is vital to the success of a development. Like in many developed countries, developers in Hong Kong select architects based on a set of criteria. Price is not the only consideration in the process, and decisions rely heavily on subjective judgement. By conducting a questionnaire survey, the research reported here identified the common criteria for selection and their relative importance for an objective selection. This involved the use of an evaluation method called the analytical hierarchy process (AHP). Survey data from projects with similar characteristics were used to compute the criteria weights. Multi-criteria models for seven out of 27 categories of project were built with reference to the computed weights derived from the survey. In addition, a computer program, called the Architectural Consultant Selection System (ACSS), was designed to illustrate a logical approach for the evaluation of prospective consultant architects based on the models constructed.     

Expert System Tools for Construction Planning and Control

The potential utilization of expert systems in construction management has drawn considerable attention in recent years. Many prototype systems were developed and have been described in previous studies. None of these studies, however, has addressed the basis for the selection of an expert system building tool (ESBT), the most important component in developing such systems. This paper presents a set of criteria for such selection. The criteria is then applied to investigate nine commercially available ESBTs, including four microcomputer-based tools, for building a knowledge-based expert system for construction planning and control. The criteria, although developed for specific application, could be readily extend to cover other problem domians.     

The UK building education recruitment crisis: a call for action

There is a growing urge for a shift from ‘lowest-price wins’ to ‘multi-criteria selection’ practices in the contractor selection process. The rationale is to achieve best value (for money) for the client. Earlier investigations have found that the tender price (i.e. capital cost) still dominates the final selection decision despite increased emphases on the need for contractor selection based on ‘value’. This paper provides insights into the evaluation of contractors' attributes, particularly for project-specific criteria (PSC), that is, criteria against which tendering contractors may be considered. The importance attached by clients to the ‘lowestprice wins’ philosophy is also reported. The perceived importance of PSC (i.e. their influence on final selection choice) is determined through a structured questionnaire survey of UK construction clients. The results show an increasing use of PSC. It is also found that ‘lowest-price’ is not now necessarily the client's principal selection criterion, but rather, the realization that cost has to be tempered with evaluation of PSC in any attempt to identify value for money.     

A study of construction mediator tactics—Part I: Taxonomies of dispute sources,mediator tactics and mediation outcomes

Constructed facilities are a major component of the built environment. Nevertheless, construction is of long-duration, high value and dispute-prone. As such, dispute is a regular feature in construction and consumes resources that would otherwise be used in a more productive manner. The use of mediation has been regarded as a flexible, cost-effective, and non-threatening way to dispute resolution. Reported studies on construction mediation have been instrumental in bringing out key success factors and the advantages over other adversarial resolution processes. Moreover, mediation is a form of assisted negotiation; hence the skill of a mediator shall have pivotal effect on the mediation outcome. In fact, the appropriate use of tactics by a mediator shall have deciding effect on the chance of success. Notwithstanding, the implication on tactics in relation to the nature of dispute cannot be discarded. In these contexts, a study that examines the inter-relationships among dispute sources, mediator tactics and mediation outcome was conducted in Hong Kong. The study is broadly divided into two parts. Part (I) deals with the development of taxonomies of construction dispute sources, mediator tactics and outcomes, employing the technique of Principal Component of Factor Analysis (PCFA). A total of eight, nine and four taxonomies for dispute sources, mediator tactics and outcomes were identified, respectively. Based on these results, Part (II) of the study examined the contingent use of mediator tactics in the contexts of dispute sources and mediation outcomes.     

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.     

Survey of construction lawyers' attitudes and practice in the use of ADR in contractors' disputes

Continuing a survey of contractors' perceptions about alternative dispute resolution (ADR) this paper seeks to report an investigation of the level of involvement of legal advisors to the construction industry in the dispute resolution process and the perceptions that legal professionals have about the use of ADR in construction disputes. The research findings are that contractors are likely to involve lawyers in the dispute resolution procedure, particularly when disputes concern a legal issue, when the parties to the dispute are entrenched in their argument, or when the other party insists on using legal professional assistance. In these defined circumstances, legal advisors will be influential in determining the potential use of ADR. The paper concludes that lawyers are unlikely to recommend ADR for most disputes between contractors, particularly if the dispute resolution process is perceived to involve the use of delay by main contractors, if the parties are fixed in their arguments or if they are exhibiting adversarial behaviour in their approach to the dispute. In these circumstances lawyers and their clients prefer the force of the formal systems over conciliatory ADR procedures.     

Towards efficient and objective work sampling: Recognizing workers' activities in site surveillance videos with two-stream convolutional networks

Capturing the working states of workers on foot allows managers to precisely quantify and benchmark labor productivity, which in turn enables them to evaluate productivity losses and identify causes. Work sampling is a widely used method for this task, while suffers from low efficiency as only one worker is selected for each observation. Attentional selection asymmetry can also bias its uniform object selection assumption. Existing vision-based methods are primarily oriented towards recognizing single, separated activities involving few workers or equipment. In this paper, we introduce an activity recognition method, which receives surveillance videos as input and produces diverse and continuous activity labels of individual workers in the field of view. Convolutional networks are used to recognize activities, which are encoded in spatial and temporal streams. A new fusion strategy is developed to combine the recognition results of the two streams. The experimental results show that our activity recognition method has achieved an average accuracy of 80.5%, which is comparable with the state-of-the-art of activity recognition in the computer vision community, given the severe camera motion and low resolution of site surveillance videos and the marginal inter-class difference and significant intra-class variation of workers' activities. We also demonstrate that our method can underpin the implementation of efficient and objective work sampling. The training and test datasets of the study are publicly available.     

Selecting a suitable procurement method for a building project

Building procurement has become a fashionable term with industry practitioners and researchers. It determines the overall framework and structure of responsibilities and authorities for participants within the building process. It is a key factor contributing to overall client satisfaction and project success. The selection of the most suitable procurement method consequently is critical for both clients and project participants, and is becoming an important and contemporary issue within the building industry. The problem, nevertheless, lies in the fact that there has been limited empirical research in this field of study. Postal questionnaire surveys of 41 clients and 35 consultants were carried out, and were used to obtain experience of and attitudes to a variety of procurement methods and the criteria used for selection. The findings indicate that a simple set of the criteria generally is adequate and sufficient for procurement path selection, and that there is a reasonable consensus on the appropriate weighting for each path. Moreover, it is shown that, contrary to expectations, similar clients generally do not have similar procurement needs.     

Evaluating prequalification criteria in contractor selection

A quantitative model for selecting construction contractors which utilizes the multi-attribute analysis technique is being developed. Prequalification criteria for inclusion in the model have been identified and weightings to mirror their respective importance in the selection process determined. A series of independent evaluations which facilitate the consolidation of these criteria into a standard prequalification form is presented. The paper may help selection practitioners in reviewing both the areas of investigation and the evaluation methods they employ when selecting construction contractors.     

Dynamic investigation of a concrete footbridge using finite element modelling and modal analysis

In this article, the application of a manual updating method for finite element (FE) model updating of a concrete footbridge using modal analysis approach is described in detail. An FE model was developed using DIANA (FEM software package) to estimate the response of structure under free-vibration analysis. Afterwards, ambient vibration test (AVT) was conducted to extract the dynamic properties. The fundamental mode shapes of the structure were successfully identified applying ARTeMIS (modal analysis computer program). The mode shape pairs of initial FE model and a complete set of test results were employed for manual updating. A parametric study was carried out to specify the most sensitive parameters of the model. For this purpose, boundary conditions, mass density and Young's modulus of elasticity were examined as uncertain parameters. Attempts to calibrate the primary FE model revealed that the spring constants of supports were the most effective parameters for updating process. The FE model was calibrated considering three main criteria consisting of combination of natural frequencies/mode shapes and modal assurance criteria (MAC)/mode shapes. The calibration strategy performed in the present study, including parametric study on uncertain parameters of initial FE model, parameter and target response selection and MAC calculation based on modified formulation, has been discussed. The updated FE model and the measured mode shape counterparts exhibited very good correlation.     

Meta-分析的方法学局限性及其适用领域

人群研究,尤其是临床研究需要重复,但重复研究往往会产生不一致的研究结果,采用系统综述及时综合分析同一问题相关研究便成为循证决策的基础,系统综述中可以对原始研究数据实现统计合并的Meta-分析已在越来越多领域得到广泛应用。但Meta-分析本身存在局限性,是否适用于所有类型研究的统计合并,尚存争议。有鉴于此,本文在介绍系统综述步骤和Meta-分析基本原理及统计合并计算步骤的基础上,进一步分析Meta-分析的误差来源,解释随机效应模型与固定效应模型的区别,旨在引导人们客观理解Meta-分析的方法学局限性,审慎使用Meta-分析,在进行临床决策时审慎解读Meta-分析结果,尤其是基于随机效应模型的统计合并。