Nationwide Personal Transportation Survey Research Articles

Transit Service, Parking Charges, and Mode Choice for the Journey to Work: An Analysis of the 1990 NPTS

In this paper, the effects of transit service and parking charges on the choice of commuters to drive alone, carpool, or use transit are estimated. The analysis is based on data for 20 Consolidated Metropolitan Statistical Areas from the 1990 Nationwide Personal Transportation Survey, FTA’s Section 15, and the Texas Transportation Institute s estimates of traffic congestion. Both the level of transit service and the likelihood of being charged for parking are found to have significant positive effects on the likelihood of choosing transit for the commute. The results also indicate that improving transit access leads to a very small increase in transit’s mode share, while improving the level of service produces a much greater mode share increase.

Travel Behavior of the Poor after Welfare Reform

In 1996, President Bill Clinton signed into law the Personal Responsibility and Work Opportunity Reconciliation Act, also known as welfare reform. As part of this act, Congress established welfare block grant programs that included a set of provisions intended to promote employment. In the aftermath of these reforms, policy makers turned to transportation as one strategy to transition welfare recipients and other low-income adults rapidly into the labor market. As the foundation for these transportation programs, studies documented the travel patterns of the poor and highlighted the limited access of these individuals to automobiles. Given the many changes since the 1990s, it is time to revisit these data. This study draws on the 1995 Nationwide Personal Transportation Survey and the 2009 National Household Travel Survey to examine changes in the commute travel of low-income adults since welfare reform. The data provide evidence that the reliance on automobiles has increased significantly over time; the growth reflects the many advantages of cars in increasingly decentralized environments. However, some population groups—particularly the carless—have become more dependent on public transit to access work. These findings suggest the importance of protecting and expanding vital transit services for those who need them, as well as acting on behalf of low-income households that may be better served through personal vehicular travel.

Effectiveness of Bayesian Updating Attributes in Data Transferability Applications

This paper presents the findings from an analysis of several Bayesian updating scenarios in the context of data transferability. Bayesian updating has been recognized as having great potential for use in the transportation field, especially in the simulation of travel demand and other transportation-related data. For local areas where comprehensive data collection is too costly and infeasible, Bayesian updating can be used to synthesize travel demand data in a process generally referred to as data transferability. Bayesian updating has been occasionally employed for transferring travel data; however, various aspects and disadvantages of its use have been insufficiently studied. This work addresses issues about Bayesian updating techniques in data transferability, including a comparison of the use of conjugate and nonconjugate formulations in the updating models, their relative effectiveness, and impacts of the quality of the prior information on final results. The study shows that, in general, updating small local samples of travel attribute data with prior information from national data sources provides an improved estimate of local travel attributes compared with using the local sample only. However, this study found that the inclusion of all available historical data in the prior distributions does not necessarily improve the quality of the updating results. Therefore, careful analysis of the applicability of the prior information to the desired context is necessary when a Bayesian updating formulation is used. The 2001 National Household Travel Survey and the 1995 Nationwide Personal Transportation Survey were used for the demonstration exercises in this study.

California vehicle license fees: incidence and equity

Most states tax the value of residents' motor vehicles. In recent political debates over the future of these levies, the relative effects of these taxes on different socioeconomic groups have been a prominent question. By linking data from the Nationwide Personal Transportation Survey with estimates of vehicle values from consumer vehicle pricing guides, the socioeconomic and demographic incidence of California's Vehicle License Fee is examined. After the effects of state and federal income tax deductions are taken into account, the fee is found to be as regressive as the state's sales tax.

Propensity to Telecommute

Telecommuting is the substitution for work at the workplace with work at home or other locations close to home. The interest in telecommuting stems from its potential benefits in trip reduction, congestion mitigation, cost saving for office spaces, increased productivity, and better home–work balance. The factors that influence people's telecommuting behavior were explored by using data from the 1995 Nationwide Personal Transportation Survey and 2001 and 2009 National Household Travel Survey. A comprehensive analysis was undertaken, and the trends over several years were examined. The analysis advances the understanding of the characteristics of workers who telecommute according to detailed categories of telecommuting frequency. The findings are essential as a first step toward estimating and incorporating telecommuting in the travel demand forecasting process.

Short trips: An opportunity for reducing mobile-source emissions?

This paper examines how conversion of automobile trips of less than 3 miles to other transportation modes reduces emissions. Short trips contribute disproportionately to emissions because of cold starts. An analysis is conducted of short-trip behavior across the US using the 1995 Nationwide Personal Transportation Survey. The data is used to develop likely scenarios of mode conversions for short trips, which are then applied to estimate emission savings using MOBILE6 cold start and running emission factors for volatile organic compounds, nitrogen oxides, carbon monoxide, and carbon dioxide. The results suggest that reducing short auto trips would modestly reduce mobile source air pollution, but emission reductions are high compared to most federally-funded surface transportation interventions aimed at improving air quality. Enhanced the community pedestrian environment to encourage short trip mode conversion also produces co-benefits such as increased physical activity and subsequent reductions in chronic diseases.

Associations of Cycling with Urban Sprawl and the Gasoline Price

Determine the relationships between cycling and urban sprawl and between cycling and the gasoline price. Cross-sectional multivariate regression analyses using pooled data from two individual-level national surveys to analyze the effects of variations in levels of urban sprawl and the gasoline price on cycling as a form of physical activity. Metropolitan areas representative of the U.S. population, 1990 to 2001. Behavioral Risk Factor Surveillance System: 146,730 individuals at least 18-years-old in the United States; Nationwide Personal Transportation Survey: 73,903 individuals at least 18-years-old in the United States. Self-reported information on bicycling served as the dependent variable. Urban sprawl and the gasoline price served as key independent variables. Living in a metropolitan area with a lower degree of urban sprawl increased the probability of cycling in the past month by 3.4 to 4.4 percentage points and 1.6 to 2.1 percentage points from the means for men and women, respectively. Increasing the gasoline price by one dollar increased the probability of cycling by 4.3 to 4.7 percentage points and 2.9 to 3.5 percentage points for men and women, respectively. Results indicate that the prevalence of cycling is higher in less sprawling areas and areas with higher gasoline prices. More research is needed to refine results on how individuals respond to incentives and the roles that monetary and time costs play in improving public health.

Relationships among Community Characteristics and Walking and Bicycling for Transportation or Recreation

Compare walking and bicycling for transportation and recreation with the percentage of the community devoted to parklands. Behavioral Risk Factor Surveillance System (N = 206,992), Nationwide Personal Transportation Survey (N = 409,025), and Trust for Public Land (N = 55) data were used to estimate recreational walking and bicycling, utilitarian walking and bicycling, and parkland as a percentage of city acreage. Data were linked at the metropolitan statistical area or city level (N = 34). Pearson correlation coefficients were used to assess the associations among recreational and utilitarian walking and bicycling and parkland acreage. Utilitarian walking and bicycling and parkland acreage were significantly correlated (r = .62, p < .0001). No significant relationships were observed for leisure time walking or bicycling. Communities with more parks had significantly higher levels of walking and bicycling for transportation. Urban design features associated with leisure time physical activity might differ from those associated with transportation-related physical activity. Further studies are needed to articulate the relationships among community attributes and purposes of physical activity.

Developing Custom Tools for Deriving Complex Data from Travel Survey Databases

Data from large-scale travel survey databases, such as the Nationwide Personal Transportation Survey (NPTS) and the National Household Travel Survey (NHTS), are often used to derive complex parameters for transportation modeling applications not originally targeted by the surveys. When situations demand complex data manipulation tasks, publicly available tools for the purpose do not obviate the need for data users to sift through entire databases and develop custom solutions. This paper presents a flexible methodology for developing custom database tools for cost-effectively deriving application-specific information from travel survey data. The seven-step methodology accounts for assessment of needs, verification of validity of travel survey data to the application, establishment of scientific justification, development of functional requirements of the system, development of data model, definition of processes, and development and testing of tools. To demonstrate the methodology, a case study involving derivation of locality-specific parameters for emission factor models from the NPTS and NHTS databases is presented. With the use of this methodology, a custom database application called Travel-Related Inputs Model for MOBILE6.x (TRIMM) was developed for this case study. The working mechanisms of TRIMM are illustrated. The methodology outlined, though specific to travel survey databases, is sufficiently generic to be used for developing custom tools to derive various modeling parameters from large transportation databases.

Developing Custom Tools for Deriving Complex Data from Travel Survey Databases

Data from large-scale travel survey databases, such as the Nationwide Personal Transportation Survey (NPTS) and the National Household Travel Survey (NHTS), are often used to derive complex parameters for transportation modeling applications not originally targeted by the surveys. When situations demand complex data manipulation tasks, publicly available tools for the purpose do not obviate the need for data users to sift through entire databases and develop custom solutions. This paper presents a flexible methodology for developing custom database tools for cost-effectively deriving application-specific information from travel survey data. The seven-step methodology accounts for assessment of needs, verification of validity of travel survey data to the application, establishment of scientific justification, development of functional requirements of the system, development of data model, definition of processes, and development and testing of tools. To demonstrate the methodology, a case study involving derivation of locality-specific parameters for emission factor models from the NPTS and NHTS databases is presented. With the use of this methodology, a custom database application called Travel-Related Inputs Model for MOBILE6.x (TRIMM) was developed for this case study. The working mechanisms of TRIMM are illustrated. The methodology outlined, though specific to travel survey databases, is sufficiently generic to be used for developing custom tools to derive various modeling parameters from large transportation databases.

Two Minutes per Person per Day Each Year

During the past several decades significant changes in travel behavior in the United States have occurred. Evidence from the Nationwide Personal Transportation Survey series and the 2001 National Household Travel Survey (NHTS) indicates that the average daily travel time per person has increased by 1.9 min per year between 1983 and 2001. The objective of this paper is to explore the growth of daily travel time expenditures. Changes in society, technology, incomes, attitudes, and sociodemographic and household structure have been hypothesized as having contributed to the travel time growth. This analysis explores those variables and their relationship to increases in travel time. Aggregate values are used to investigate the relationships between daily travel time expenditures and sociodemographic characteristics. This paper comments on the share of travel time growth that can be explained by the available variables and speculates on the implications of other factors on travel time expenditure growth. A review of the NHTS data set and an analysis of the relationships between the data set and travel time expenditures make clear that travel budget changes that appear to be related to the set of available variables do not explain the full reason for the significant increase in travel time spending. The increases are across all market segments: age, income, gender, ethnicity, household composition, and so on. Thus, shifts in demographic or other traveler conditions do not fully explain the increases in trip making. That has a significant implication for transportation planning–-traditional sociodemographic predictors for trip making do not appear to be sufficiently causal to be useful for understanding current and future factors influencing trip making and travel expenditure changes.

Trip-Chaining Trends in the United States: Understanding Travel Behavior for Policy Making

This paper uses data from the 1995 Nationwide Personal Transportation Survey and the 2001 National Household Travel Survey to examine trip-chaining trends in the United States. The research focuses on trip chaining related to the work trip and contrasts travel characteristics of workers who trip chain with those who do not, including their distance from work, current levels of trip making, and the purposes of stops made within chains. Trends examined include changes in the purpose of stops and in trip-chaining behavior by gender and life cycle. A robust growth in trip chaining occurred between 1995 and 2001, nearly all in the direction of home to work. Men increased their trip chaining more than women, and a large part of the increase was to stop for coffee (the Starbucks effect). It was found that workers who trip chain live farther from their workplaces than workers who do not. It was also found that, in two-parent, two-worker households that drop off children at school, women are far more likely than men to incorporate that trip into their commute and that those trips are highly constrained between 8:00 a.m. and 9:00 a.m. An analysis was done of workers who stopped to shop and those who did not but made a separate shopping trip from home; a large potential to increase trip-chaining behavior in shopping trips was found. Results of these analyses have important policy implications as well as implications for travel demand forecast model development. Finally, this paper uses these analyses to develop conclusions about the utility of transportation policies and programs that use the promotion of trip chaining as a primary travel demand management strategy.

Two Minutes per Person per Day Each Year: Exploration of Growth in Travel Time Expenditures

During the past several decades significant changes in travel behavior in the United States have occurred. Evidence from the Nationwide Personal Transportation Survey series and the 2001 National Household Travel Survey (NHTS) indicates that the average daily travel time per person has increased by 1.9 min per year between 1983 and 2001. The objective of this paper is to explore the growth of daily travel time expenditures. Changes in society, technology, incomes, attitudes, and sociodemographic and household structure have been hypothesized as having contributed to the travel time growth. This analysis explores those variables and their relationship to increases in travel time. Aggregate values are used to investigate the relationships between daily travel time expenditures and sociodemographic characteristics. This paper comments on the share of travel time growth that can be explained by the available variables and speculates on the implications of other factors on travel time expenditure growth. A rev...

Trip-Chaining Trends in the United States

This paper uses data from the 1995 Nationwide Personal Transportation Survey and the 2001 National Household Travel Survey to examine trip-chaining trends in the United States. The research focuses on trip chaining related to the work trip and contrasts travel characteristics of workers who trip chain with those who do not, including their distance from work, current levels of trip making, and the purposes of stops made within chains. Trends examined include changes in the purpose of stops and in trip-chaining behavior by gender and life cycle. A robust growth in trip chaining occurred between 1995 and 2001, nearly all in the direction of home to work. Men increased their trip chaining more than women, and a large part of the increase was to stop for coffee (the Starbucks effect). It was found that workers who trip chain live farther from their workplaces than workers who do not. It was also found that, in two-parent, two-worker households that drop off children at school, women are far more likely than men to incorporate that trip into their commute and that those trips are highly constrained between 8:00 a.m. and 9:00 a.m. An analysis was done of workers who stopped to shop and those who did not but made a separate shopping trip from home; a large potential to increase trip-chaining behavior in shopping trips was found. Results of these analyses have important policy implications as well as implications for travel demand forecast model development. Finally, this paper uses these analyses to develop conclusions about the utility of transportation policies and programs that use the promotion of trip chaining as a primary travel demand management strategy.

Elderly patients presenting to the emergency department: Do physicians identify unsafe drivers?

Study objectives: The 1995 US Department of Transportation Nationwide Personal Transportation Survey reports that the crash involvement rate per 1 million miles traveled triples from age 65 up to age 85. The fatality rate per 1 million vehicle miles increases by 500% for the same populations. The Pennsylvania Vehicle Code requires physicians to report patients with a “condition that could impair their ability to drive” to the Pennsylvania Department of Transportation (PENNDOT). Thirteen diagnoses of disorder or disability are listed on the Department of Transportation Initial Reporting Form. We conduct a survey of elderly patients presenting to the emergency department (ED) to determine driving status, ED diagnosis compared with PENNDOT's reportable diagnoses, and driving recommendations by discharge physician. Methods: A 1-month convenience sample of patients aged 65 years or older was asked to participate in a study of their driving practices. The survey was conducted in a community teaching hospital ED with an annual census of 60,000. Verbal informed consent was obtained. Participants were asked whether they had a valid driver's license. Drivers were asked about their driving habits, whether their ability to drive had ever been questioned, and whether they felt safe to drive. Each driver's ED diagnosis, medication list, and potential reportable diagnoses were recorded. Physician driving recommendation at discharge was noted. One author (RSB) reviewed all medical records to determine potential reportable diagnoses. Institutional review board/Health Insurance Portability and Accountability Act–approval was obtained. Descriptive statistics were used. Results: Of 112 patients asked to participate, 31 (28%) were excluded because of the following: 24 declined consent; 4 younger than 65 years; 2 incomplete data; 1 surveyed twice on the same visit. Of the remaining 81 patients, 24 (30%) did not have a valid license or had voluntarily stopped driving. Thirty-nine (48%) patients were judged not to have a reportable diagnosis. Of the 18 patients judged to have a reportable medical condition, only 3 were instructed not to drive at discharge. There was no documentation on any record that a PENNDOT form was completed. Family had previously discussed driving ability with 9 patients. All 9 reported continued driving at the ED visit. Two other patients had voluntarily stopped driving after being told by their family physician to stop. Conclusion: Elderly patients often present to the ED with conditions that could impair their ability to drive. A sample of patients in our ED demonstrates a lack of discharge instructions about driving and underreporting of potentially hazardous conditions to PENNDOT. Of the 11 patients told by family or physician to stop driving, only the 2 patients instructed by the family physician discontinued driving. Emergency physicians should be educated about reporting requirements in their locale. Elderly ED patients should have a driving history obtained. Patients with conditions that could impair their ability to drive should be given driving-specific discharge instructions. Reporting to the appropriate agency should be completed if required by the practitioner's state.

Trends in Walking for Transportation in the United States – 1995 and 2001

1355 PURPOSE: To examine trends in walking for transportation among U.S. adults and youth. METHODS: Changes in travel trips of one mile or less (adults) and trips to school of one mile or less (youth aged 5–15) were analyzed using travel data from the 1995 Nationwide Personal Transportation Survey (N = 95,360, 47.4% males, mean age 38.5 ± 20.6 years) and the 2001 National Household Transportation Survey (N = 60,282, 47.4% males, mean age 39.1 ± 23.0 years). In 2001, the survey methodology changed to include additional clarification of transportation trips and asked for walking for leisure and exercise. Non-transport trips were excluded from the analyses. RESULTS: Adults reported more walking trips in 2001 than 1995 (19.5% compared to 16.7%). Trips to school of one mile or less also increased from 1995 to 2001 (31.3% to 34.6%). CONCLUSIONS: In spite of small increases in walking between 1995 and 2001 accompanying a change in survey methodology, U.S. adults and youth fall short of meeting Healthy People 2010 walking objectives for trips one mile or less (25% for adults and 50% for youth).

Methodology for Deriving Vehicle Activity Parameters from Travel Survey Databases

Vehicle activity parameters are key inputs to mobile source emissions modeling. Emission factors are sensitive to these inputs, which vary by geography, time of day, and trip purpose classifications. The state of the practice in emission factor modeling relies heavily on default parameters imbedded in the models. Therefore, there is a need for deriving these inputs for the various geographic regions to provide realistic values. Methods are described for deriving vehicle activity parameters from travel surveys, such as starts distribution, fraction of vehicle miles traveled (VMT), trip length distribution, soak time distributions, and the VMT mix distribution. This methodology is applied for deriving vehicle activity parameters from Nationwide Personal Transportation Survey databases and conducting a sensitivity analysis of the MOBILE6 model with respect to these derived inputs. Inputs derived from travel surveys are compared with MOBILE6 default inputs; wide variations in the inputs are observed. A sensitivity analysis of MOBILE6 related to travel survey inputs reveals that emission factors can vary by as much as 26% when compared with those obtained with default inputs. A statistical analysis has determined that the difference in emission factors is significant enough to warrant the development of locale-specific inputs.

Automobile Reliance Among the Elderly: Race and Spatial Context Effects

Abstract Mobility is a necessary condition for the social and emotional well‐being of older people. To meet their mobility needs, the elderly assign pivotal importance to the automobile despite the potential challenge of driving cessation and searching for alternatives to automobile transportation. Older persons’ generally strong reliance on the automobile varies, however, by land use patterns (density) as well as by demographic and socioeconomic characteristics. This paper analyzes the effects of spatial context and personal attributes on automobile reliance among the elderly. Using the 1995 Nationwide Personal Transportation Survey (NPTS) trip data, two models of automobile reliance among elderly (65+) trip makers are estimated. The results show that spatial context effects of automobile reliance vary by demographic characteristics; in particular, they are more pronounced for black than for white elderly. Moreover, race variation in automobile reliance is strongest in urban locations rather than less dense spatial contexts. Finally, the differentiation between being a passenger rather than a driver is salient in order to understand locational and racial variations in automobile reliance among the elderly.

Travel, location and race/ethnicity

This paper examines the relationship between residential location and travel among ethnic and racial population segments using the 1995 US Nationwide Personal Transportation Survey (NPTS) data. Using measures of total daily travel, I explore the effects of metropolitan location and local neighborhood characteristics. I estimate models which test for both independent and interaction effects of race/ethnicity. I find that there are significant differences in travel characteristics across race/ethnic groups. There are independent effects associated with race/ethnicity. Individual characteristics such as sex, age and household income, have different effects on daily travel. Metropolitan location is not related to total daily travel. However, residential neighborhood characteristics are related and have different effects across race/ethnic groups. I conclude that our understanding of travel behavior is largely an understanding of the white majority population, which dominates analysis when race/ethnicity is not explicitly considered.

Departure Time Choice for Recreational Activities by Elderly Nonworkers

A discrete choice analysis was performed to study the temporal preferences of elderly persons for recreational trips. Departure time choice studies for recreational activities helped in gaining an understanding of flexible travel behavior. Elderly persons form the fastest-growing age groups, and results from the 1995 Nationwide Personal Transportation Survey indicate an increase in travel by elderly persons. This study was the first part in a study of the interaction of age, emerging transport technologies, and activity participation. Modeling departure time choice for elderly persons is critical in understanding the travel needs of an aging population to provide adequate services and enhance efficacy of transport systems and user mobility. The study makes possible an analysis of the impacts on congestion, air quality, and associated mitigation efforts. Results of this study confirm that travel patterns for elderly persons are different from those of the general population; they prefer the earlier part of the day for recreational trips. The implications of increased daytime travel may include the need for additional emergency or incident response units, particularly in rural areas. This study may be used to gauge how to best offer alternative means of transport such that they will be most effective in meeting the demands of nonworkers for nonwork trips.