Taha Hossein Rashidi

A joint model for mode choice and escort decisions of school trips

A considerable shift has occurred in mode choice behaviour and escort pattern of students for their school trips around the world during the last few decades. This shift towards using more non-active modes has undesirable consequences, including physical inactivity among students, traffic jams during peak hours, and adverse environmental impacts. Hence, understanding the behaviour of decision-makers with regard to the mode choice and escorting pattern selection is crucial for controlling the trend of the shift and promoting active modes. This study is the first effort to mathematically model the mode choice and accompaniment pattern selection by parents for the school trip of students, in a joint modelling structure as it is believed that these two decisions are jointly made by parents. Two modelling formulations are used: a nested logit (NL) model and a copula-based model. Results showed that the copula model outperforms the NL model. It was also found that modelling these two decisions in an independent manner can result in misleading policy assessments.

Modeling Household Vehicle Transaction Behavior: Competing Risk Duration Approach

Household vehicle ownership analysis is an important and emerging topic in transportation research. Transportation researchers are interested in examining policy scenarios that can decrease the number of vehicles in a household fleet or encourage alternative transit. Many researchers have studied aspects of vehicle ownership and developed various aggregate and disaggregate models in different frameworks, including hazard-based duration models. Duration models can model the competing nature of vehicle transactions in a household and predict the timing of a change in vehicle ownership. Competing duration models are used to analyze the household vehicle ownership decision. Three vehicle transaction decisions (purchase, trade, and disposal of a vehicle) are considered. Dynamic variables that represent the state of the household and household location characteristics, an exogenous logsum variable representing maximum utility of vehicle class and vintage choice, and time-varying covariates (e.g., number of adults and household income) are considered in the model. Independent hazard models for each outcome and a competing hazard model are developed and compared.

Dynamic Activity Generation Model Using Competing Hazard Formulation

Rule-based activity scheduling microsimulation models often generate activities for individuals to engage in randomly, on the basis of observed activity rates from survey data. These microsimulation models try to represent more closely the process of activity pattern development. However, the dynamics underlying the activity generation process are often not considered, especially in regard to competition between activities for the limited time resource. This work, then, develops a methodology for generating activities on the basis of the time since the last activity of the same type was generated, by using a hazard-based formulation. In addition, the model explicitly accounts for the competition between activities through the use of a competing hazard framework. The results show that observed activity rates and temporal distributions from survey data can be replicated through simulation of the model in an activity-based scheduling model, the agent-based dynamic activity planning and travel scheduling (ADAPTS) activity scheduler.

Incorporating Multiskilling and Learning in the Optimization of Crew Composition

AbstractThe presence of multiskilled workers in a crew can increase the crew’s productivity through reducing inefficiencies and supervision requirements, while also providing on-the-job learning opportunities for single-skilled workers. The effect of the presence of multiskilled workers on the learning rate of workers, which is also a function of skill level and experience, and thus on the crew’s productivity, is especially significant in repetitive construction projects. This paper presents a mathematical model for identifying the optimal combination of single-skilled and multiskilled workers with different levels of experience in the crew to minimize the duration of construction projects by accounting for the overlapping effects of multiskilling, skill level, and learning on the crew’s productivity. The model is applied to an illustrative case project to demonstrate the practicality of the model. The optimum crew compositions for different activities involved in the case project are identified using a s...

Parametric Hazard Functions: Overview

Hazard models are used only moderately in the transportation field compared with their levels of application in other areas, such as medicine, political science, and economics. Many specifications of the hazard models are not well known, whereas the primary application of hazard models is limited to a basic proportional continuous hazard formulation with continuous failure time and Weibull baseline hazard function. Besides the recent advances in the methodology of hazard-based models, the basic proportional hazard formulation remains the proffered hazard-based modeling approach. This paper aims to present some popular specifications of hazard-based models and also discusses some formulations that are less frequently used in practical models. In this study, the Weibull baseline hazard, which is a monotonic function, is replaced by the nonmonotonic log logistic function, and the modified formulation is presented. The log logistic and Weibull formulations are also presented, not only in continuous form but also in discrete hazard formulations for applications in which the failures are observed in discrete time intervals. Finally, all four combinations of discrete and continuous formulations with Weibull and log logistic baselines are discussed with the option of unobserved heterogeneity of type of gamma distribution. The accelerated failure time model, which is an alternative to the proportional hazard models, is discussed. This paper attempts to present a comprehensive overview of the applications of the duration model in the field of transportation.

Effect of Variation in Household Sociodemographics, Lifestyles, and Built Environment on Travel Behavior

Household and individual demographics, attributes, and dynamics have significant effects on travel behavior and the overall performance of the transportation system. This study attempts to examine the effects of household demographic changes on the travel attributes of households grouped into several homogeneous lifestyle clusters. With the use of the National Household Travel Survey 2001 data, more than 20 travel attributes including number of auto trips, trips per tour, transit usage, and average commute distance are analyzed. To investigate the impact of changing demographics on household- and individual-level travel attributes, the best-fit distributions for a large set of travel attributes are introduced. Then a detailed comparison between the resulting distributions across different lifestyles and demographics is presented.

BIM-enabled sustainability assessment of material supply decisions

Purpose Enhancing sustainability of the supply process of construction materials is challenging and requires accounting for a variety of environmental and social impacts on top of the traditional, mostly economic, impacts associated with a particular decision involved in the management of the supply chain. The economic, environmental, and social impacts associated with various components of a typical supply chain are highly sensitive to project and market specific conditions. The purpose of this paper is to provide decision makers with a methodology to account for the systematic trade-offs between economic, environmental, and social impacts of supply decisions. Design/methodology/approach This paper proposes a novel framework for sustainability assessment of construction material supply chain decisions by taking advantage of the information made available by customized building information models (BIM) and a number of different databases required for assessment of life cycle impacts. Findings The framework addresses the hierarchy of decisions in the material supply process, which consists of four levels including material type, source of supply, supply chain structure, and mode of transport. The application is illustrated using a case study. Practical implications The proposed framework provides users with a decision-making method to select the most sustainable material alternative available for a building component and, thus, may be of great value to different parties involved in design and construction of a building. The multi-dimensional approach in selection process based on various economic, environmental, and social indicators as well as the life cycle perspective implemented through the proposed methodology advocates the life cycle thinking and the triple bottom line approach in sustainability. The familiarity of the new generation of engineers, architects, and contractors with this approach and its applications is essential to achieve sustainability in construction. Originality/value A decision-making model for supply of materials is proposed by integrating the BIM-enabled life cycle assessment into supply chain and project constraints management. The integration is achieved through addition of a series of attributes to typical BIM. The framework is supplemented by a multi-attribute decision-making module based on the technique for order preference by similarity to ideal solution to account for the trade-offs between different economic and environmental impacts associated with the supply decisions.

Behavioral Housing Search Choice Set Formation

The housing search process, a topic of interest to both practitioners and researchers, starts with an alternative formation and screening practice. Due to the limitation of cognitive capacity, household members at this level evaluate potential alternatives based on many factors, such as lifestyle, preferences, and so on, to form a manageable choice set. This article attempts to provide a detailed study of this screening and filtering practice to develop a modeling framework that can replicate the choice set formation process. In order to show the potential of the method, one prospective decision criteria—the average desired commute to work distance—is considered the potential attribute that the household evaluates for feasible housing alternatives. It is postulated that alternatives will only be included in the choice set if the average work distance satisfies the household distance threshold. This article explores the viability of using proportional hazard models in the housing search process. Some of the specifications of hazard-based models that are typically used on temporal data are examined on average work distance. Several household sociodemographic attributes from eight waves of the Seattle Metropolitan Area’s Puget Sound Transportation Panel (PSTP) are utilized for model estimation, along with built environment variables, characteristics of the supply side of the market, and several other economic indicators. The approach presented in this article provides a remedy for the large choice set problem typically faced in discrete choice modeling.

Complementing Travel Diary Surveys with Twitter Data: Application of Text Mining Techniques on Activity Location, Type and Time

A growing body of literature in social science has been devoted to extracting new information from social media to assist authorities in manage crowd projects. In this paper geolocation (or spatial) based information provided in social media is investigated to utilize intelligent transportation services. Further, the general trend of travel activities during weekdays is studied. For this purpose, a dataset consisting of more than 40,000 tweets in south and west part of the Sydney metropolitan area is utilized. After a data processing effort, the tweets are clustered into seven main categories using text mining techniques, where each category represents a type of activity including shopping, recreation, and work. Unlike the previous studies in this area, the focus of this work is on the content of the tweets rather than only using geotagged data or sentiment analysis. Beside activity type, temporal and spatial distributions of activities are used in the classification exercise. Categories are mapped to the identified regions within the city of Sydney across four time slots (two peak periods and two off-peak periods). Each time slot is used to construct a network with nodes representing people, activities and locations and edges reflecting the association between the nodes. The constructed networks are used to study the trend of activities/locations in a typical working day.

Application of a nested trivariate copula structure in a competing duration hazard-based vehicle transaction decision model

ABSTRACT Vehicle ownership has been the subject of numerous transportation studies, which typically have adopted a variety of econometric frameworks at both aggregate and disaggregate choice modeling levels. These models have covered various aspects of vehicle ownership, including vehicle transaction behavior, number of vehicles held, vehicle type choice, and vehicle use. Vehicle transaction models have been developed in both static and dynamic paradigms. However, traditionally transaction timing has been overlooked in static vehicle ownership models despite the significant role that it plays in explaining vehicle ownership behavior. The decision about transaction type is typically assumed to be independently made; therefore, independent timing models are developed for each transaction type. This study aims to introduce a joint transaction type and timing model at the disaggregate level of individuals using a discrete competing proportional hazard model. The inter-correlation among multiple transaction types is modeled in this study by utilizing a set of multivariate Archimedean copula density functions to approximate the multivariate probability density function for the error terms of transaction types in a fully nested structure.