Somak Datta Gupta

Traveler Information Tool with Integrated Real-Time Transit Information and Multimodal Trip Planning: Design and Implementation

The chief objective of the PATH2Go multimodal traveler information application is to improve the accessibility and the quality of real-time traveler information and to make transit a known and viable choice for travelers. PATH2Go was developed as part of a field test on the US-101 corridor in the San Francisco Bay Area of California, with the primary hypothesis that travelers would benefit from real-time multimodal traveler information and therefore would be likely to consider using transit. PATH2Go integrates a web-based multimodal trip-planning tool that uses real-time transit, traffic, and parking information; a web-based search tool that finds real-time information about transit arrivals and schedules; and a mobile application that provides personalized en route transit trip information. PATH2Go integrates these major components of traveler information in one platform and makes real-time information easily accessible to travelers. The PATH2Go system architecture and major design considerations are described, and enabling technologies–including the Global Positioning System (GPS) fusing algorithm and a scenario-parsing algorithm based on GPS location data–are introduced.

Path2Go: Context-aware services for mobile real-time multimodal traveler information

Mobile platforms are now becoming a more and more important medium for providing information to travelers on the move. To improve the accuracy and relevance of the mobile traveler information, context awareness has become a active research topic. In this paper, we describe algorithms and services provided by Path2Go, a multimodal traveler information system developed by California PATH, UC Berkeley. The Path2Go activity detection algorithm, the core of the context-aware design, has made the following contributions: (1) it uses a rule-based multi-hypothesis Bayesian method for mode detection, to address the limitations of using mobile phone GPS for activity detection and increase the speed of convergence; (2) it fuses GPS data from transit vehicles and the GPS of the users mobile phone for better activity detection; and (3) it enables several experimental services, including variable-frequency client-server communication and need-based GPS use. Field testing of the Path2Go activity detection algorithms showed reasonably good results. The Path2Go application has also been made available to the public through iPhone, Android and Windows Mobile platforms, with some of the features discussed in this paper included.

Sharing vehicle and infrastructure intelligence for assisted intersection safety

In this paper, we describe a framework and system architecture for sharing of information between vehicles and infrastructure with the aim of increasing intersection safety. Emerging intersection safety applications are based on location sensing and wireless communication. We show that these applications can only be realized if vehicles and intersection can both participate and share their information and intelligence. The framework to share information is based on wireless communications, usually in DSRC mode. We first present a system architecture that uses a networking gateway in order to allow incorporation of wireless communication modes other than DSRC. Then the overhead of this extra component is examined via experiments and shown not to have a significant effect on the performance of the system. Experimental results from the implementation of the proposed architecture is reported and analyzed. For system scalability we also conducted simulations to examine different design choices for the rate of information exchange and operation of the components of the architecture. The results show that even modest cooperation of vehicle and infrastructure can be adequate to enable safety critical applications.

Evaluation of Real-Time Freeway End-of-Queue Alerting System to Promote Driver Situational Awareness

This paper presents the final results of a connected-vehicles field experiment conducted under the U.S. Department of Transportations SafeTrip-21 Initiative. A real-time freeway end-of-queue alerting system was developed and tested at 3,400 locations along San Francisco Bay Area freeways in California. The Networked Traveler Foresighted Driving Advanced Driver Assistance System, which used vehicle-to-infrastructure communication, provided drivers with an auditory alert when they approached slow traffic ahead on a freeway to improve the drivers situational awareness. The system was not a last-second collision warning; rather, it was designed to provide soft safety alerts approximately 60 s before the driver reached the slowed traffic. Twenty-four drivers participated in the experiment, and each was given an instrumented vehicle for 2 weeks. During the first week, the alerting system was active but muted, providing a measure of baseline driving behavior. During the second week, auditory alerts sounded whenever the driver approached traffic moving at least 15 mph slower. The desired outcome was an increase in driver situational awareness resulting in a smoother transition into the end of the queue and a reduction in the risk of rear-end crashes. Drivers rated the majority of alerts as either good or neutral and found the system most useful when they encountered an unexpected traffic queue. Several driving performance metrics were also examined. In addition to a smoother deceleration profile, the auditory alerts provided a small but significant reduction in mean peak deceleration rates during morning and off-peak travel as compared with baseline conditions.

Scalable Cooperative Vehicle Safety Systems: Adaptive Inter-Vehicle Communication

Scalability is one of the main challenges of cooperative vehicle safety (CVS) systems. In this paper, we describe a demonstration of the scalability solution that we have developed for CVS. The solution is an adaptive communication scheme for safety messages. The demo comprises of a demonstration of the rate control algorithm using recorded vehicle trajectories, and a live demonstration of the power control scheme using emulated interference. We show that the proposed algorithms are able to deliver considerably better performance than the baseline solution for CVS. The demonstration will use several DSRC units as well as visualization and simulation software for visualizing the network dynamics.

A traffic speed enforcement system for high speed environment based on Dedicated Short-Range Communications (DSRC) technology

The IEEE 1609 and 802.11p protocol family (also known as WAVE/DSRC or DSRC network) developed by IEEE are key wireless technologies for time-critical safety message broadcast in Vehicular Ad Hoc Networks (VANETs). The WAVE/DSRC network removes the layer-2 association procedure and thus greatly differs from traditional WiFi technologies. With this capability, critical information can be sent within a very short period, making it suitable for realizing Vehicle-to-Vehicle (V2V) safety applications and Roadside-to-Vehicle (R2V) Intelligent Transportation System (ITS) applications. In a recent project, the WAVE/DSRC technology has been studied for the use of speed enforcement system. This paper presents a case study of integrating the state-of-the-art WAVE/DSRC technology into a new-type of speed enforcement system called the Augmented Speed Enforcement (aSE) system. The design, the architecture, and the details of field tests in Los Banos, California, will be discussed. In addition, experimental results regarding the DSRC and 3G radio performance in the field will be analyzed in this paper.