Tai Stillwater

Carsharing and the Built Environment: Geographic Information System-Based Study of One U.S. Operator

A geographic information system–based multivariate regression study of an urban U.S. carsharing operator compared the use of carsharing vehicles for 16 months in 2006 and 2007 to built-environment and demographic factors. Carsharing is a relatively new transportation industry in which companies provide members with short-term vehicle access from distributed neighborhood locations. The number of registered carsharing members in North America has doubled every year or two to a current level of approximately 320,000. Researchers have long supposed that public transit access is a key factor driving demand for carsharing. The results of the study, however, find an ambiguous relationship between the activity at carsharing locations and public transit access. Light rail availability is found to have a significant and positive relationship to carsharing demand. Regional rail availability is found to be weakly and negatively associated with carsharing demand, although limitations in the available data make it impossible to ascribe the observed difference to user demand, random variation, or other factors specific to the industry.

Field Test of Energy Information Feedback: Driver Responses and Behavioral Theory

The Energy Information Administration estimates that, in 2007, U.S. domestic passenger vehicles burned 113 billion gallons of fuel and thus generated more than 16% of U.S. greenhouse gas emissions. Past field experiments and simulations suggest that energy information feedback to drivers could have spared 10% to 25% of those gallons. However, the theoretical underpinnings of past experiments have primarily been ad hoc, with application of their results limited to specific conditions of the experiment and feedback design. More rigorous behavioral theory would allow researchers to account for more variation in driver response to feedback, create testable hypotheses about the effectiveness of current systems, and provide a basis for designing more-effective systems. This paper presents drivers’ responses to energy feedback in a field test involving 98 participants from 43 households in California and compares the results with the concepts that underlie the theory of planned behavior and the extended model of goal-directed behavior. About 40% of participants reported more economical driving behaviors after viewing the feedback; estimation of actual changes in fuel use is left for future research. After viewing real-time energy information, numerous drivers reported setting goals, having emotional reactions, and creating new driving behaviors. Distraction from the primary driving task was a persistent problem for some drivers. Web-accessible information was not as motivating to participants. Finally, the study finds evidence of correspondence between theoretical behavioral factors and drivers’ responses.

Mobile App Support for Electric Vehicle Drivers: A Review of Today’s Marketplace and Future Directions

Mobile device applications (apps) are becoming an important source of information, control, and motivation for EV drivers. Here we review the current ecosystem of mobile applications that are available for EV drivers and consumers and find that apps are available in six basic categories: purchase decisions, vehicle dashboards, charging availability and payment, smart grid interaction, route planning, and driver competitions. The current range of the EV-specific mobile marketplace extends from pre-sale consumer information, charging information and control, and EV specific navigation features among other services. However, the market is highly fragmented, with applications providing niche information, and using various methodologies. In addition, we find that the barriers to more useful apps are a lack of vehicle and charger APIs (application programming interfaces), lack of data availability, reliability, format and types, and proprietary payment and billing methods. We conclude that mobile applications for EVs are a growing market that provide important direct benefits as well as ancillary services to EV owners, although the lack of uniformity and standards between both vehicle and charger systems is a serious barrier to the broader use of mobile applications for EVs.

Design Matters: Mid-Term Results from a Multi-Design Fuel Economy Feedback Experiment

Energy feedback to drivers is one method to engage drivers in energy saving driving styles. In contrast to the occasional broadcasting of general driving tips, in-vehicle energy feedback gives drivers access to accurate information about their specific driving situation on an ongoing basis. The increasing prevalence of such feedback in new vehicles suggests a belief that ongoing, in-vehicle feedback is better. However, there is little reliable evidence of the effectiveness of energy feedback in real-word driving in passenger vehicles. This study begins to fill this gap. Participants are given a commercially-available fuel consumption display and recording device to use in their personal vehicle for two months. For the first month the display is blank as the device records a baseline of driving and fuel consumption. For the second month the display is switched on to show drivers one of three feedback designs. This paper presents preliminary results (N=75) of a larger study that will include 150 drivers along the California-Nevada Interstate-80 corridor. Using a mixed-effects linear model, we find an average driving efficiency improvement of between 1.5% and 6% (gallons/100 miles) between the without- and with-feedback months, depending on the feedback designs. Categorizing trips into types based on distance and multiple speed characteristics, there are differences in the apparent effectiveness of feedback across trip types. Finally, an overall decrease in fuel consumption of 10% between periods was observed. While approximately 3% of that is explained by changes in driving behavior, the remaining 7% is due to reduced VMT.