Philip L Winters

A general architecture in support of interactive, multimedia, location-based mobile applications

The widespread use of cellular telephones and the availability of user-location information are facilitating the development of new personalized, location-based applications. However, as of today, most of these applications are unidirectional and text-based where the user subscribes and the system sends a text message when appropriate. This article describes a modular and general architecture that supports the development of interactive, multimedia, location-based applications, providing an extra level of service to the users. The flexibility of the architecture is demonstrated by presenting the wireless safety security system (Wi-Via) and other potential applications

Dynamic Management of Real-Time Location Data on GPS-Enabled Mobile Phones

Advanced location based services have the ability to track users with Global Positioning System (GPS)-enabled cell phones in real-time. These applications share a common problem; the continuous calculation and transmission of GPS fixes from the mobile phone to a server consumes a considerable amount of energy and increases data transmission costs. Therefore, an application-level algorithm is necessary to reduce the number of GPS fixes calculated and transmitted, while continuing to track the user in real-time and record an accurate representation of his or her travel path. In this paper, two complementary algorithms are presented: the critical point (CP) algorithm, which filters data points to be transmitted to the server, and the location-aware state machine, which dynamically manages the frequency of the location re-calculation update rate. Both algorithms were implemented in TRAC-IT, a Java Micro Edition (Java ME) application designed to automatically collect user travel behavior; the proposed algorithms allow TRAC-IT to build an accurate representation of the users path with a considerably reduced number of fixes while significantly extending mobile device battery life.

Impact of Carpooling on Trip-Chaining Behavior and Emission Reductions

Within an activity-based framework, the hypothesis that carpooling imposes a constraint on the way individuals organize their activities was tested, with resulting impacts on traffic peak congestion and trip-chaining behavior. The hypothesis was tested by estimating the joint probability density functions (PDFs) of subsistence, maintenance, and discretionary trips made by carpool and single-occupancy vehicle (SOV) users. Results show that whereas SOV maintenance and discretionary activities are linked to subsistence trips in a joint undertaking, carpool activities suggest discontinuity in the formation of trip chains. A comparison of the joint PDF of subsistence and discretionary activities reveals that trips are conducted either before or after the commute schedule; this results in a temporal shift that reduces peak-period traffic congestion and emission pollution. Marked differences are found to exist between SOV and carpool trip-chaining behavior. Carpoolers are more likely to engage in a greater number of cold-start trip chains; this behavior uncovers a potential negative impact on emission pollution. These findings suggest that a comprehensive approach to the evaluation of carpool programs must take into account the benefits as well as any ensuing negative externalities.

Fare pricing elasticity, subsidies, and demand for vanpool services

Transportation demand management practitioners consider pricing a crucial determinant of vanpool market demand. Publicly sponsored programs stress the significance of fare pricing and subsidies as key tools for increasing ridership. This paper investigates the effects of fares and fare subsidies on the demand for vanpool services. Using employer and employee data from the 1999 survey of the Commute Trip Reduction (CTR) program of the Puget Sound region (Washington), a conditional discrete choice model is built to analyze the choice of vanpool services with respect to competing means of transportation as a function of various socioeconomic characteristics. The predicted value of the direct elasticity is -0.73, indicating that vanpool demand is relatively inelastic with respect to fare changes. For trips below 30 miles, the individual elasticities are equivalent to the aggregate estimate. As the distance from home to work increases beyond 60 miles, individuals are less responsive to price changes. Subsidies have a relevant impact in increasing ridesharing, controlling for firm size and industry sector. Whenever employees are offered a subsidy, the predicted probability of choosing vanpool more than doubles. When considered in the context of subsidies, these results support the evidence that policies other than those intended to directly affect fare pricing, could play a relevant role in stimulating ridership. For the covering abstract see ITRD E129315.

A location-aware framework for intelligent real-time mobile applications

The Location-Aware Information Systems Client (LAISYC) supports intelligent, real-time, mobile applications for GPS-enabled mobile phones by dynamically adjusting platform parameters for application performance while conserving device resources such as battery life.

Telecommuting as a Component of Commute Trip Reduction Program: Trend and Determinants Analyses

This paper applies a generalized ordered logit model to estimate the effects of commute trip reduction (CTR) activities, journey to work distance, job characteristics, and employers’ major business types on telecommuting choices by using Washington State CTR data. Regression results suggest that employers’ CTR promotion activities play an important and positive role in commuters’ telecommuting choices. Employees are more likely to make a transition from not telecommuting to telecommuting at least 1 day per 2 weeks if employers consistently promote CTR strategies to enhance commuters’ awareness of support from employers. Employees commuting longer distances are more likely to make the transition from not telecommuting to telecommuting at least 1 day. Employees’ job characteristics and the employers major business type act either to drive or constrain employees’ telecommuting decisions.

Quantifying Position Accuracy of Multimodal Data from Global Positioning System–Enabled Cell Phones

The emergence of cell phones with embedded Global Positioning System (GPS) chips provides opportunities to push personalized real-time travel information subject to an individuals current location. One such application, a travel assistant device, notifies cognitively disabled public transportation users when it is time to request a stop and exit the vehicle. GPS-enabled cell phones must provide highly accurate real-time location data for this type of service. The components used in the data-collection process are identified, and a quantitative analysis of real-time GPS data obtained with a cell phone while walking, driving a vehicle, and riding public transportation is provided. The expectation was that position accuracy would suffer when the GPS signal was obstructed by a vehicle or the users clothing. The obtained data demonstrate the results of location fix attempts over different transportation modes in an urban environment. The highest percentage of GPS fixes (79.0%) was obtained by users walking with the cell phone open and unobstructed; walking also produced valid GPS data (i.e., location data estimated to be accurate within 30 m of the true position) 66.2% of the time. For bus trips, GPS and valid fix percentages were 71.7% and 66.1%, respectively, when the phone was held near the window; when the phone was placed in the travelers lap, these numbers fell to 51.3% and 27.8%, respectively. Car trips provided higher numbers: 77.7% and 71.6%, respectively. Location-based transportation applications are feasible using current technology, but predictive algorithms may be required to deliver highly accurate and timely location-aware services to cell phone users in highly obstructed environments.

CREATIVE SOLUTIONS FOR ASSESSING LEVEL OF SERVICE EQUALLY ACROSS MODES

Transportation professionals base the level of service (LOS) for automobile, bicycle, pedestrian, and transit modes on various criteria, and therefore the LOS is calculated differently for each mode. The current classification schemes make total transportation performance and multimodal trade-off decisions difficult to assess, and the measures do not reflect expectations. The primary objective of this Florida Department of Transportation research project was to identify new approaches for developing an LOS system that planners can use to assess automobile, bicycle, pedestrian, and transit modes of travel equally. Aided by a systematic creative thinking approach, an expert panel identified the perceived values, the feasibility, and the benefits of each alternative approach. The panel also identified the difficulties and cautions associated with each of the alternatives. Furthermore, the expert panel concluded that the fundamental need in developing a method to assess LOS equally across modes would be to correlate the levels for each mode with user perceptions. On the basis of group discussions and in consideration of Maslows hierarchy of needs, the panel postulated that a hierarchy of transportation user needs would consist of five levels: safety and security (the most basic need), time, societal acceptance, cost, and comfort and convenience (the highest need). The next task in developing a method to assess LOS equally across modes should be the scientific evaluation of the hypothesis of a transportation user hierarchy of needs to determine its validity and effectiveness.

Global Positioning System Integrated with Personalized Real-Time Transit Information from Automatic Vehicle Location

Navigation of a transit system can be a major obstacle to new riders, especially special-needs populations and tourists. For those with cognitive disabilities (approximately 14.3 million Americans, or 6% of the population), it is challenging to plan and execute a trip without assistance. A travel assistance device (TAD) software prototype for Global Positioning System–enabled phones was developed to aid new transit riders, especially those who are cognitively disabled. When riders approach their stops, the TAD vibrates and delivers audio and visual messages to the riders to request a stop and exit the vehicle. This paper reports the results of a study that integrated communication with an automatic vehicle location (AVL) system on transit vehicles into TAD, with new features, including personalized notices of estimated vehicle arrival time and of vehicle arrival. Implementation issues addressed include the limitations of accessing AVL data for real-time consumer use, integration of different transit agency data sources, and consideration of the effects of software applications (e.g., wireless data communication) on mobile phone functionality (e.g., battery life).

Empirical Analysis of Compressed Workweek Choices

This paper analyzes the trend and determinants of the compressed workweek (CWW) by using Washington State commute trip reduction (CTR) data. A multinomial logit model was applied to analyze the determinants of CWW choices by using the CTR data from 2005. Regression results indicate that the employers transportation demand management promotion level and the number of years CWW programs have been in effect have significant impacts on commuters’ decisions about CWW choices. Commuters are more likely to participate in CWW programs when employers are more supportive or the CWW program has been implemented longer. The distance from home to work is another key factor that influences commuters’ CWW choices. The longer the distance from home to work, the higher the probability that a person will choose alternative work schedules. Employees’ journey-to-work mode choices affect their choices of working on CWW schedules. Commuters using a single mode of transit and a shared ride are less likely to work on CWW schedules than those who simply drive alone to work, and commuters using mixed modes are more likely to work on a CWW schedule than those who drive alone. Employees’ decisions to participate in CWW programs are also affected by their job titles and their employers major business type.