Mahmudur Rahman Fatmi

Life-Oriented Approach of Modeling Commute Mode Loyalty and Transition Behavior

This study developed a dynamic model for individuals’ commute mode choice over their lifetime by using retrospective survey data. The study conceptualized that individuals reassessed their choice of commute mode when they relocated to a new residential location. Following the re-appraisal, people either continued using the same mode, which was considered mode loyalty, or made a transition to a new mode, which was considered mode transition in this study. The study developed a panel-based random-parameters logit model. One key feature of this study is a life-oriented approach to accommodate the effects of life-cycle events, longer-term changes, life-oriented sociodemographic transitions, and accessibility transitions. The model results suggest that the high-income group tends to be car loyal. No car ownership over the lifetime and the addition of a job increase the probability of transit loyalty. Individuals with no children in the household and residing in an area with high walk and bike usage have a higher probability to be loyal to active transportation. A decrease in household income and tenure transition from owned to rental are likely to trigger a transition from car to transit. However, the presence of children and the addition of a car increase the transition propensity from transit to car. The model results suggest that the use of life-oriented characteristics to explain longer-term commute mode loyalty and transition behavior provides important behavioral insights into the dynamics of individuals’ travel behavior over their lifetime.

Modeling mobility tool ownership of youth in Toronto, Ontario, Canada

This paper presents the findings of the modeling of mobility tool ownership of the youth population in the greater Toronto and Hamilton area (GTHA) in Ontario, Canada. Research on mobility tool ownership is limited. The key contribution of the research is to enhance the understanding of how neighborhood characteristics and accessibility affect mobility tool ownership among GTHA youth. The study exclusively considered youth between the ages of 17 and 19 years; at this age the subjects passed through a transitional stage in the GTHA because of opportunities for ownership of types of mobility tools. This study used data from the 2006 Transportation Tomorrow Survey, a household-based travel survey of the GTHA. The study used a latent class choice modeling approach to account for unobserved heterogeneity, which was often ignored in traditional choice modeling. The results suggest that the latent class logit model outperforms the conventional multinomial logit model according to model fit and its ability to evaluate various parameters across latent classes. Several sociodemographic characteristics, trip attributes, accessibility measures, and neighborhood characteristics were found to explain different types of mobility tool ownership of the youth population. Finally, the results revealed that latent heterogeneity existed in the sampled population. The research offers important behavioral insights into the formation of travel habits of youth that could be useful in shaping the travel behavior of Torontos young adults.

Longitudinal Vehicle Transaction Model: Assessment of Lead and Lagged Effects of Longer-Term Changes and Life-Cycle Events

This paper presents a dynamic vehicle transaction model developed with data from a retrospective survey conducted in Halifax, Canada. The study investigated four types of vehicle transaction decisions, including first-time vehicle purchase, vehicle acquisition, vehicle disposal, and vehicle trade. A panel-based latent segment logit (PLSL) model was developed to account for repeated transaction decisions and to capture unobserved heterogeneity among the sample households. The study took a life-oriented approach by examining the lead and lagged effects of longer-term changes and life-cycle events. The PLSL model was estimated for two latent segments, and the model results suggest that profound heterogeneity exists, as evident in parametric values of the two segments. The life-cycle event represented by the birth of a child might trigger vehicle acquisition in Segment 1. In contrast, that life-cycle event might deter an acquisition decision in Segment 2. The model confirmed historical deposition effects of key life events. For instance, a 2-year lagged effect on vehicle acquisition was seen with the birth of a child. Moreover, the model results revealed that first-time vehicle purchase behavior was considerably different from the decision to acquire a vehicle. For example, for the longer-term change represented by the addition of a job, significant heterogeneity across the two segments for a first-time vehicle purchase decision was seen and a 3-year lagged effect was confirmed. A positive relationship for the decision to acquire a vehicle in both segments was found for the same variable, and a 1-year lagged effect was confirmed. Finally, the study provided important behavioral insights for targeting specific groups of the population to promote sustainable travel behavior.

Microsimulation of life-stage transitions and residential location transitions within a life-oriented integrated urban modeling system

Abstract This paper presents microsimulation of life-stage transitions and residential location transition processes within a life-oriented agent-based integrated Transport Land Use and Energy (iTLE) modeling system. The iTLE assumes that individuals and households are the agents, and parcels are the objects. It is conceptualized following the life-course perspectives and theories to address the evolution of multi-domain decision interactions over the life-course of the agents. Residential location is simulated as a two-stage process of residential mobility, and location choice. Life-stage simulation includes aging, death, birth, out-migration, in-migration, and household formation. The iTLE is implemented at a yearly time-step from 2006 to 2021 for Halifax, Canada. A 100% synthetic population is generated for the base year 2006, which shows a SRMSE value of 0.37 and APE measures of less than 5% for 89% of the DAs. The simulation results are validated with the 2011 Census information. The validation results suggest that the iTLE generates reasonably satisfactory population estimates. For example, around 52% of the DAs show an APE value of less than 30%, and 37% of the DAs show a difference in the number of households of less than ±50. The predicted results regarding the spatio-temporal evolution of Halifax suggests an increase of around 14% population in 2021 compared to 2007. Younger population residing closer to the CBD are predicted to be more frequent movers than older population residing farther away from the CBD. Higher proportions of the households are predicted in the locations within 25 km from the CBD over the years. Proportion of households in these high density neighborhoods are predicted to increase from 68% in 2007 to 71% in 2021. In 2021, a higher density of single person households are predicted in the urban core. Density is predicted to be more variable and skewed towards suburban neighborhoods as household composition changes through marriage and child birth.

Baseline Synthesis and Microsimulation of Life-stage Transitions within an Agent-based Integrated Urban Model

Abstract: This paper presents baseline synthesis and microsimulation of life-stage transitions within an agent-based integrated Transport Land Use and Energy (iTLE) modeling system. The baseline synthesis involves generation of synthetic population and vehicle ownership level synthesis. Synthetic population in generated in two stages: (1) generation of synthetic population at the dissemination area (DA) level, controlling for household- and individual-level attributes; and (2) allocation of the synthetic population at the micro-spatial unit of parcel using a logit-link model. Vehicle ownership synthesis involves a multinomial logit model to determine the vehicle ownership level for the base year. The life-stages of the synthetic population are simulated longitudinally at a yearly simulation time-step within the iTLE framework. The simulated life-stages include: aging, birth, death, in-migration, out-migration, and household formation. The iTLE is coded in the C# DotNET programming platform. A 100% synthetic population is generated for Halifax, Canada. The baseline synthesis and life-stage simulation results are satisfactory. For instance, population synthesis results suggest that around 62.81% of the DAs show an error percentage range of -5% to +5%.

Modeling Travel Tool Ownership of the Elderly Population: Latent Segmentation-Based Logit Model

A latent segmentation-based logit (LSL) modeling framework investigated the travel tool ownership of the elderly population in the greater Toronto area, Ontario, Canada. This study utilized data from the 2006 Transportation Tomorrow Survey conducted in the greater Toronto area. The study developed five mutually exclusive travel tool ownership combinations or bundles for older adults. One of the unique features of this study is the development of an LSL model to capture unobserved heterogeneity in the older adults’ travel tool ownership decisions. The LSL model captures unobserved heterogeneity by allocating individuals to discrete latent segments through a latent segment allocation model. The model results suggest that the LSL model is estimated for two latent segments in which less frequent trip makers are more likely to belong to Segment 1 and more frequent trip makers have a higher probability of belonging to Segment 2. Moreover, the model results suggest that considerable heterogeneity exists among the older adults in the two segments. For instance, older adults residing in a neighborhood with a higher percentage of owned dwellings prefer to own multiple travel tools in one latent segment and reveal an opposite relationship in another segment. Moreover, older adults living closer to regional business centers have a higher probability of owning a monthly transit pass in one segment and exhibit an opposite relationship in another segment. This diversity in travel behavior should be addressed within the transportation and land use policies to ensure an effective and equitable transportation system for older adults.

Optimized Aggregate Gradation for Bangladesh

Aggregate is one of the most important and strength determining ingredients of concrete as it serves as reinforcement and occupies three quarter of the total volume of concrete. Moreover, for good compact concrete, aggregate with minimum void is always desirable. This paper represents a study on obtaining the effective dense gradation by combining naturally available aggregate in Bangladesh. In this purpose a program has been developed based on analytical approach to find out the desired mix proportion of different aggregate samples to reach the target of getting an compact, economic and environment friendly concrete. Finally after preparing the concrete in the laboratory with different mix design ratio and combined gradation of prepared single sized aggregate is found to have 20% more strength than that of the concrete made with the same design mix and combination of aggregate gradation presently available in the industry.