Issam Srour

Accessibility Indices: Connection to Residential Land Prices and Location Choices

Specifications of accessibility indices range from simple minimum-travel-time indices, to measures of cumulative opportunities within specified distance or time thresholds, to maximum utility measures. Models are presented that relate a variety of general accessibility indices for the Dallas–Fort Worth region of Texas to property valuations for single-family dwelling units and commercial units, and to household residential location choices. Hedonic models are used to assess how important access is to property valuations, while controlling for improvement attributes and parcel size. Multinomial logit models are used to derive logsum measures of accessibility as well as to assess the effect of access on location choices, while controlling for household demographics. Three functional specifications of access measures were used. Job accessibility (a proxy for work and other opportunities) was estimated to affect residential land values positively in statistically and economically significant ways, suggesting—as hypothesized here—that land rents track property owners’ assessments of accessibility, whereas other common accessibility measures do not perform as well. After controlling for this measure, access to park space (proxy for availability of outdoor recreational activities) and access to retail jobs (proxy for shopping opportunities) were not valued in the land market. Distances to regional central business districts and household heads’ workplace locations played important roles in location predictions, often in the presence of the more general access measures. Residential location choice model results suggested which indices are better measures of accessibility. Different functional specifications appeared useful here. Cumulative opportunities access measures were most helpful in predicting residence location, but differences in predictive power were relatively small.

An Optimization-Based Model for Maximizing the Benefits of Fast-Track Construction Activities

Fast-track construction projects have become more popular in recent years in response to growing industry demand. By allowing downstream construction activities to start with incomplete information from upstream design activities, fast-tracking (through overlapping) allows for shorter project duration at the expense of potential rework. This leaves practitioners with the challenge of determining the optimal fast-tracking strategy to meet project schedule requirements while avoiding excessive amounts of rework. This paper presents an optimization-based model that serves as a decision support tool in scheduling fast-track construction activities. The model takes into consideration information exchange between upstream and downstream activities and uses the concepts of sensitivity and evolution to maximize the net benefits of fast-tracking. The model is illustrated on an ongoing construction project, which was analysed under various overlapping scenarios. The results indicate substantial time savings depending on the speed of evolution and sensitivity. The project schedule can be shortened by up to 50 days without causing excessive amounts of rework.

Learning Curves in Construction: A Critical Review and New Model

AbstractThis paper brings forth from the literature a series of learning curve models and evaluates them through the lens of the construction industry. The review suggests that there is still no consensus on which model provides the best fit and predictability for construction data. As such, this paper puts forth a new model that is suitable for the modern construction industry as it accommodates for both mechanization and forgetting. The proposed model is similar to the Wright model (an exponential model of learning), but, through recursion, places more emphasis on recent data. The proposed model shows an error of less than 1% when predicting the cumulative average completion times in three out of four cases examined.

Pilot-based assessment of the economics of recycling construction demolition waste

The significant amount of waste generated from construction demolition has become a chronic problem in many developing countries. Using data obtained from demolition contractors and various other sources, this paper proposes a framework for proper handling of construction demolition waste (CDW) to serve as a decision support tool in countries suffering from the lack of national CDW management guidelines. The framework is then demonstrated through a case study in the city of Beirut, Lebanon, and a sensitivity analysis is carried out to examine the economic feasibility of developing a recycling facility. The analysis showed that in order for a facility to be feasible, a gate fee should be charged in the presence of a market for recycled aggregates. The results confirm the significance of instigating and implementing legislation to control illegal dumping, constructing, and managing engineered landfills, and establishing markets for recycled CDW.

Effectiveness of the earth tube heat exchanger system coupled to a space model in achieving thermal comfort in rural areas

The aim of this work is to investigate by modelling the possibility of reducing the operational energy of a typical house without negatively affecting its embodied energy. This is done through consideration of different building materials coupled with the use of an earth to air heat exchanger (EAHE) for fresh air supply and cooling. For known indoor and outdoor conditions and for given building materials (thermal capacity and conductance), a ventilation controller determines the amount of flow rate needed to temperate the indoor air temperature to achieve thermal comfort. Different wall configurations are assumed for each of the living zone and the bedroom zone of the apartment. It is found that the use of an optimal wall configuration in each zone coupled with the EAHE results in 76.7% energy savings compared with the reference case with conventional cooling.

Career Planning and Progression for Engineering Management Graduates: An Exploratory Study

Abstract: When faced with the decision of selecting an advanced degree, many engineers opt for management related studies rather than further specialization in a technical field. This article attempts to highlight the reasons behind such choices, and explores the role that a Masters degree in Engineering Management (MEM) plays in career planning and progression. A survey of 58 MEM graduates, who completed their studies at a prominent university in Lebanon between 1992 and 2009, reveals that the majority of the respondents follow a linear career path, rapidly paving the way towards managerial positions. For most of the respondents, earning a graduate degree in engineering management played a primary role in, or at least contributed to, making this shift. The article concludes with a diagram sketching the possible career paths for MEM graduates. By showing the number of years spent at different career stages, the diagram serves as a career-planning tool for MEM graduates, engineers, managers, and researchers.

Occupant Satisfaction with Indoor Environmental Quality: A Study of the LEED-Certified Buildings on the Arizona State University Campus

Following a recent surge in the green building movement, several universities now require the U.S. Green Building Councils (USGBC) Leadership in Energy and Environmental Design (LEED) certification for all their new facilities. This paper investigates the actual occupant satisfaction of LEED-certified higher education facilities through studying seven LEED-certified buildings located on the Arizona State University (ASU) campus in Tempe, Arizona. Indoor environmental quality (IEQ) occupant satisfaction surveys were used to collect data from more than 160 occupants. The surveyed LEED buildings earned, on average, a 77.6% overall satisfaction rating. The results show ASU LEED buildings performed better than the Center for the Built Environment (CBE) benchmark, which is based on 59,359 completed surveys. In addition to comparing the results with other studies, this paper highlights an inconsistency between the LEED points earned for IEQ and the actual level of occupant satisfaction. In addition, the paper showcases a need for improvement in the USGBC rating system in such a way that correlates the awarded LEED rating with the actual performance of the building during the occupation phase, as opposed to the intended performance during the design and construction stages.

Construction Demolition Waste Management in Lebanon

The significant amount of waste generated from construction demolition has become a chronic problem in Lebanon. In the city of Beirut alone, approximately one million ton of construction demolition waste (CDW) has been generated over the past two years. The country is suffering from a constant problem in the management of its solid waste; and therefore, devising methods to manage the amount of CDW is a must and is the primary goal of an ongoing research at the American University of Beirut. This paper presents the first major step in this research effort. The paper studies the quantification, composition, and managing of CDW in Lebanon by examining three case studies consisting of 50 to 60-year old buildings being demolished for reconstruction. Based on the case study analysis and a set of interviews conducted with demolition contractors, the paper proposes a set of rules and regulations necessary for proper handling of CDW in the context of the Lebanese construction industry.

Developing a Carbon Footprint Calculator for Construction Buildings

Carbon footprint is commonly defined as the total amount of greenhouse gases produced directly or indirectly as a result of an activity. The term carbon footprint has become the standard for measuring the environmental impact of activities in several sectors (e.g., transportation, energy, construction). While there have been several studies documenting calculators that estimate the carbon footprint of individual activities (e.g., driving a car, riding an airplane), the literature describing the process of carbon footprint calculations for construction activities remains limited. The few existing tools that calculate the carbon footprint of construction buildings do not take into account some of the major variables in the design and construction process (e.g., properties of selected materials, location of suppliers). In an effort to improve the accuracy of carbon footprint calculations, this paper presents a tool that estimates the total carbon footprint of construction buildings while taking into consideration project characteristics (e.g., size, location, material choices). The calculator relies on data collected from construction material suppliers and covers the various phases of a construction project. Through a case study, the research team illustrates the use of the tool to identify the activities with high carbon emissions.

A Framework for Managing Construction Demolition Waste: Economic determinants of recycling

The significant amount of waste generated from construction demolition has become a chronic problem in several developing countries. Using data obtained from demolition contractors and various other sources, this paper proposes a framework for proper handling of construction demolition waste (CDW) in countries suffering from lack of national CDW management procedures and facilities. This framework, which serves as a decision support tool, is then applied to the case of Beirut, and a sensitivity analysis is carried out to examine the economic feasibility of developing a recycling facility. The analysis shows that the feasibility of introducing a new recycling facility is highly dependent of the interrelationship between the landfill tipping fee and the recycling gate fee coupled with the marketability of the by- product as well as regulatory enforcement to control illegal dumping and properly manage engineered landfills.