Bhargava Sana

Joint Analysis of Time Use and Consumer Expenditure Data: Examination of Two Approaches to Deriving Values of Time

Estimating the value of time is of considerable interest to transportation professionals charged with evaluating infrastructure investments. Two approaches used to calculate the value of time are the microeconomic utility theory approach and the structural equations modeling method. In an effort to clarify the interpretation and the relationship between the values of time derived from these two approaches, both models were applied to a synthesized data set of one-person, one-worker households created by merging records from the 2008 American Time Use Survey data set with records from the 2008 Consumer Expenditure Survey data set of the United States. The microeconomic model results show that people in the sample data set work until the marginal utility of work is nearly zero. This finding implies that the value of leisure is nearly equal to the wage rate. Comparisons of model parameter estimates between the microeconomic model and the structural equations model suggest that the models offer vastly different measures of the value of leisure. Although the microeconomic model offers a utilitarian measure suitable for computing user benefits, the structural equations model provides a much smaller value of leisure, implying that it is a measure of the willingness to pay as represented by the average relationship between monetary expenditure and time allocation.

Joint Model of Vehicle Type Choice and Tour Length

Tour-based microsimulation model systems are increasingly being applied to the forecasting of travel demand. This paper examines the relationship between two dimensions of tours: the type of vehicle (in a household that owns multiple vehicles of different types) chosen to undertake the tour and the overall length (distance traveled) of the tour. These two dimensions are of much interest in the current planning context, in which concerns about energy sustainability and greenhouse gas emissions are motivating planners to seek ways to mitigate the adverse impacts of automotive travel. Moreover, virtually all tour-based models currently used do not explicitly account for choice of vehicle type in the modeling of tour attributes, despite the critical importance of the choice of vehicle type for energy and emissions analysis. This paper presents a joint discrete–continuous model of choice of vehicle type and length of tours. Estimation results suggested that significant common unobserved factors affected vehicle type choice and length of tours. These factors justified the use of modeling approaches with joint simultaneous equations to model tour attributes. The model specification in which vehicle type choice affected tour length performed better than the specification in which tour length affected vehicle type choice. This outcome suggested that choice of vehicle type (and allocation to household members) was a longer-term choice that influenced shorter-term tour-length choices.

Tour based and supply chain modeling for freight: integrated model demonstration in Chicago

Abstract Despite recent advances in freight and commercial vehicle modeling, the current state of the practice methods are not adequate to address the increasingly complex issues related to freight demand. This project includes research that has combined tour based truck models and logistics supply chain models for urban commercial vehicle movements and that has demonstrated a functional model framework that addresses the limitations of current freight demand forecasting models. The research was performed by Resource Systems Group Inc., in partnership with the Chicago Metropolitan Agency for Planning and the University of Illinois at Chicago. The project introduced a model framework and focused on the estimation of each of the model components, described the approach to linking the models together in the model application, and presented initial results from applying the model in the Chicago region. The models were estimated for demonstration purposes from several sources, since there were no datasets that could support all aspects of the new framework. To make the demonstration more practical, two commodities were chosen to model from the data available (food products and manufactured products). The models developed for the project were applied using software developed in R, an open source platform. A data collection program to support the estimation, calibration, and forecasting of the framework for future use was recommended. Further efforts to improve this framework with new data, model improvements, and forecasts would be welcome.

Exploration of Time Use Utility Derived by Older Individuals from Daily Activity-Travel Patterns

With the growing population of older persons around the world, much attention is being paid to designing transportation systems and built environments that meet the mobility needs and desires of this aging population. On the basis of evidence from travel surveys showing that individuals in older age brackets engage in fewer activities outside the home, there is growing concern that aging persons are increasingly at risk of experiencing social exclusion and diminished quality of life. In this study, the activity time allocation patterns of those 65 years of age and older are compared with those of other age groups to understand better the extent to which older persons may be suffering from diminished levels of satisfaction with their daily activity pattern. Using an activity-based time use utility measure, this study quantifies the amount of welfare or satisfaction that individuals derive from their activity–travel pattern. It is found that older individuals actually exhibit the highest values of time use utility of all age groups; any loss in utility due to diminished out-of-home activity engagement is more than compensated for by gains in utility accrued from the pursuit of discretionary activities at home. The finding challenges the notion that older individuals are experiencing lower levels of satisfaction from their activity patterns but point to the need to design transportation systems that cater to those with physical and mental impairments, regardless of age.

Formulation of an Activity-Based Utility Measure of Time Use: Application to Understanding the Influence of Constraints

This paper presents and demonstrates a methodology to compute a composite time use utility measure that accounts for in-home and out-of-home activity engagement and time allocation patterns of individuals. The measure could be used for welfare analysis in the context of a policy intervention and to model the search and adaptation routine that individuals may follow in choosing an alternative activity travel pattern in response to a policy intervention. The proposed measure can be implemented as a postprocessor for activity-based model systems to evaluate the satisfaction that travelers derive from their overall daily activity travel pattern. With data from the 2005 American Time Use Survey, the analysis was performed for a sample of women stratified by employment status, income, and presence of children. Comparisons of time use utility measures across these cross-classified groups offer insights into the influence of temporal (employment), monetary (income), and household obligation (children) constraints on the utility individuals derive from their activity travel pattern. In general, it was found that time use utility values were affected most adversely by temporal constraints, followed by monetary constraints, and then by the presence of children.

Quantitative Analysis of Impacts of Moving Toward a Vehicle Mileage-Based User Fee

This paper offers a broad examination of the revenue generation and social equity implications of a national mileage-based user fee that could be substituted for all or part of the current gas tax. Data from the 2001 National Household Travel Survey are combined with documented elasticity values that can be used to calculate changes in vehicle fleet composition and miles of travel by time of day in response to price signals. These data provide the basis for calculating the impacts of a mileage-based user fee system. It is found that modest mileage-based fees of just 0.5 cent per mile to 1.3 cents per mile can offer revenue streams that replace current gas tax revenue. In addition, the mileage-based user fee system appears to have minimal, if any, differential impacts across income classes and thus eliminates any potential equity concerns that may arise from the implementation of such a user fee system. Impediments to a mileage-based user fee system appear likely to be technological and personal privacy issues as opposed to transportation or social equity issues.

Socio-economic and transport trends in India and the United States: a preliminary comparative study

Abstract The demand for travel is growing very rapidly in developing nations around the world. Increasing population, standards of living, vehicle ownership, massive infrastructure investments, and economic and recreational opportunities are just some of the factors contributing to increases in travel demand. While the rate of increase in travel demand may begin to slow in some developed economies of the world, the rapidly developing economies (such as China and India) are just beginning to experience the rapid increases in travel demand that the developed economies experienced several decades ago. Thus, there are challenges and issues in the development of multimodal transport systems, understanding of travel behavior and drivers of growth in travel demand, and deployment of advanced analysis tools that are common to both the developed and developing economy contexts. Resource and data constraints, as well as workforce training and development issues, confront transportation professionals both in developed and rapidly developing environments. At the same time, there are socio-economic, cultural, and demographic differences that persist across geographical contexts. This paper highlights some of the socio-economic and transport trends and conditions in India and the United States to shed light on differences and similarities between the two contexts. The paper highlights the trajectory of travel demand in the two contexts with a view to identify potential strategies that a rapidly developing nation such as India can deploy to accommodate growth in a sustainable way.