Yehiel Rosenfeld

Decision support model for semi-automated selection of renovation alternatives

The initiation of a renovation project usually involves a long process of contemplation under conditions of high uncertainty. Large organizations, that own many buildings and other facilities, can greatly benefit from a decision-support model, which can be transformed to a computerized semi-automatic tool. It will aid them develop and execute a reasonable and economical policy of rehabilitating, renovating, remodeling, or rebuilding their facilities. This paper presents a systematic four-module decision support model: (a) Preliminary survey of background conditions; (b) Evaluation and ranking of the facilitys physical condition; (c) Generation of viable alternatives for rehabilitation, renovation, or reconstruction; and (d) Quantitative techno-economic comparison among the alternatives, and systematic presentation of recommendations. The paper concludes with a demonstrative example, concerning the renovation of a 25-year-old dining facility, that highlights both the practicality of the model and the benefits from utilizing it.

Root-Cause Analysis of Construction-Cost Overruns

AbstractDespite their negative impact on the construction industry, cost overruns have become an almost natural part of building and infrastructure projects. This paper examines the phenomenon as a worldwide problem, identifies its root causes, ranks them (on a local basis), and analyses them. Root-cause analysis is not merely an arbitrary expression; rather, it is a systematic, formal, well-structured methodology, used as part of the total quality-management approach. The expand–focus principles and techniques were applied in this research for assembling an initial, as wide as possible, inclusive list (pool) of 146 potential causes gathered from the international professional literature as well as from prominent local experts. Through two cycles of expand–focus, they were filtered and merged into merely 15 independent universal root causes. These were further investigated through a cross-sectional survey among 200 local construction practitioners who ranked the 15 universal root causes according to their...

Cost of quality versus cost of non‐quality in construction: the crucial balance

The research is a pioneering attempt to determine the optimal level of investment in quality by construction companies. The methodology is based on quantifying the four types of quality‐related costs in residential construction, and relates them to each other by expressing them all as percentages of the relevant total construction revenues (revenues to the company due to construction, excluding land, etc.). The findings reaffirm, on the one hand, that investing in quality is a worthy strategy and that, in the situations examined, the ratio of the direct benefits to the investment (in terms of savings on internal and external failures) is at least 2:1. On the other hand, the findings also show that an excess of quality costs (prevention and appraisal) is wasteful. Above a certain level of investment, the extra benefits are marginal, and thus do not offset the extra costs. Statistically fitted graphs, based on actual quantitative data, support this hypothesis, and provide approximate boundaries of effective versus ineffective investments in quality. In this study, the optimal range lies between 2% and 4% of the companys revenue. Investing less than 2% in prevention and appraisal will definitely entail higher failure costs, whereas an investment of over 4% most probably will not pay itself back.

‘CHASTE’: construction hazard assessment with spatial and temporal exposure

CHASTE—‘Construction Hazard Assessment with Spatial and Temporal Exposure’—is a conceptual model that enables forecasting of safety risks in construction projects for different trades, at appropriate levels of detail and reliability for different planning windows and managerial purposes, in a highly automated fashion. Unlike earlier models, CHASTE explicitly accounts for the fact that construction workers are frequently endangered by activities performed by teams other than their own. The risks to which workers are exposed change through time, as the activities performed and the physical environment of construction sites change. CHASTE uses a knowledge base of construction activities and probabilities of loss‐of‐control events, coupled with a project’s construction plan and a digital building model, to forecast risk levels for work teams. It has been implemented in prototype software and tested on two projects.

Innovative construction methods

The construction industry is relatively slow in developing and adopting new technologies and usually prefers conservative, well-known practices over innovative construction methods. The paper discussus the logic and reasons behind this behaviour, while pointing to special circumstances in recent history when the balance between risk and benefits tilted towards the benefits, providing the opportunity for innovation to flourish. Such a situation occurred in Israel between 1990 and 1992, as a continuous stream of new immigrants was arriving in the country mainly from the former Soviet Union. The urgent need for mass housing, without creating the slums of the future, stimulated unique economic approaches of risk sharing in large-scale projects and gave rise to the implementation of dozens of innovative construction methods. Three of these unconventional methods are presented and analysed as representative of three larger categories: revival of methods that performed reasonably well in the past but have lapsed...

Quality circles in temporary organizations: lessons from construction projects

Abstract The common belief that temporary organizations such as construction projects are inappropriate for the participative, people-building approach of quality circles seems to have blocked penetration of the latter into the construction industry. This paper presents some counterintuitive arguments claiming that the special characteristics of such project organizations actually create even better opportunities for QCs than stable worksettings. Findings of field experiments with QCs at construction sites are presented and analysed in both tangible and non-tangible terms, substantiating these arguments. The discussion highlights differences between regular QC programmes and those at temporary settings.

Automation of existing cranes: from concept to prototype

Abstract This paper describes the conversion of an existing full-scale 5-ton payload crane into a semi-automatic “Handling Robot”. By its size, degrees of freedom, and mode of operation this crane resembles typical construction cranes, which can be enhanced in the same manner. The new control system allows operation of the crane in either a manual or a semi-automatic mode, and it can be taught to memorize up to 50 different benchmarks, i.e. particular points at the construction site, as well as safe routes among them. The major components of the system include: a programmable controller, three speed regulators, three encoders, several limit switches, a wireless remote control set, and a user-friendly M.M.I. (Man-Machine-Interface). Most of the components can be installed externally in the vicinity of the cranes joints and inside the cabin, with minimal intervention in the original wiring. Following the physical retrofitting of the crane, a series of tests examined performance, accuracy, repeatability, and safety aspects. They demonstrated a 15–50% shortening of typical work cycles, high accuracy and repeatability, and a generally safer operation due to pre-tested paths and smoother movements with less sway and swing of the load.

Cost-plus and incentive contracting: Some false benefits and inherent drawbacks

Two problems associated with cost-plus and incentive contracts in the construction industry are discussed: the financial costs of an earlier construction start through the use of a ‘fast-tracked’ design-build cycle, and the counterproductive effects of the ‘adverse selection’ of competing construction firms that must occur in a cost-plus or incentive contract environment. Though they stem from basic economic principles, these problems are often ignored in the conventional wisdom. The authors argue that the demonstration of these serious, commonly overlooked drawbacks should result in a decrease in the use of cost-plus or incentive contracts.

Achieving Construction Innovation through Academia-Industry Cooperation—Keys to Success

The conception, development, implementation, and commercialization of a crane-mounted vision system through close academia-industry cooperation illustrate how such joint efforts can yield research and development success. The vision system was devised to help solve the problem of blind lifts and other viewing concerns related to the operation of tower cranes on construction sites, thereby enhancing safety and productivity and saving money. In addition to other expected difficulties, the project faced the traditional skepticism of a conservative industry reluctant to adopt changes. The paper relays the chronology of the project and analyzes, stage by stage, the steps taken by the university-based developers to work in harmony with construction companies in particular, and with the industry at large, to ensure success. Lessons drawn from this experience are offered to future academician developers in the field of construction technology.

Robotic mapping of building interior—precision analysis

Abstract Autonomous map-making of building interiors is becoming a widely used tool in robotics for various applications. One of the major problems to be dealt with in the development of this tool is the precision of the coordinates obtained in the process of mapping. Previous developments in map-making focused on the empirical examination of the accuracies. This paper presents an analysis of the precision of a map created by a robotic arm of 6 articulated degrees of freedom mounted on a mobile carriage and utilizing a laser beam range-finder for horizontal and vertical rotational scanning. The analysis shows that two parameters are the main factors affecting the precision of the map: (1) orientation of the carriage on which the robot is mounted and (2) distance between the sensor and the walls being scanned. It was found that if the carriage location accuracy is 1 cm, then in order to achieve coordinate precision not worse than 3 cm: (1) the carriage orientation accuracy must be at least 0.1 ° and (2) the distance between the sensor and the walls being scanned should not exceed 3m.