This paper describes the architecture, functionality, and field demonstration results of a newly developed dedicated short-range communication–based vehicle-to-infrastructure work zone traffic information system with vehicle-to-vehicle assistance. The new system is portable and can automatically acquire important work zone travel information such as the travel time and the starting location of congestion and then relay this information to drivers approaching the congestion site. Such information can help drivers make informed decisions on route choice, prepare for upcoming congestion, or both. The authors had designed a similar system earlier; that system had limited congestion coverage and message broadcast ranges, but the new system can achieve a much longer broadcast range (up to a few tens of kilometers) and can handle much longer congestion coverage (up to a few kilometers) by incorporating vehicle-to-infrastructure communication assisted by vehicle-to-vehicle communication. The system requires only a single roadside unit to acquire traffic data by engaging the vehicles traveling on the road whether within or outside of its direct wireless access range. From the traffic data, the system estimates important traffic parameters such as travel time and starting location of congestion and periodically broadcasts this information back to the vehicles approaching the congestion well before they enter the congested area. The results from the field demonstration show that the new system can adapt to a dynamically changing work zone traffic environment and can handle much longer congestion lengths as compared with the previous system, which used only vehicle-to-infrastructure communication without vehicle-to-vehicle assistance.

There is a growing need for vehicle positioning information to support Advanced Driver Assistance Systems (ADAS), Connectivity (V2X), and Automated Driving (AD) features. These range from a need for road determination (<5 meters), lane determination (<1.5 meters), and determining where the vehicle is within the lane (<0.3 meters). This work examines the performance of Global Navigation Satellite Systems (GNSS) on 30,000 km of North American highways to better understand the automotive positioning needs it meets today and what might be possible in the near future with wide area GNSS correction services and multi-frequency receivers. This includes data from a representative automotive production GNSS used primarily for turn-by-turn navigation as well as an Inertial Navigation System which couples two survey grade GNSS receivers with a tactical grade Inertial Measurement Unit (IMU) to act as ground truth. The latter utilized networked Real-Time Kinematic (RTK) GNSS corrections delivered over a cellular modem in real-time. We assess on-road GNSS accuracy, availability, and continuity. Availability and continuity are broken down in terms of satellite visibility, satellite geometry, position type (RTK fixed, RTK float, or standard positioning), and RTK correction latency over the network. Results show that current automotive solutions are best suited to meet road determination requirements at 98% availability but are less suitable for lane determination at 57%. Multi-frequency receivers with RTK corrections were found more capable with road determination at 99.5%, lane determination at 98%, and highway-level lane departure protection at 91%.

The future deployment of dedicated short-range communication (DSRC) technology requires that applications with their bases in DSRC be integrated with existing traffic management techniques so that vehicles not equipped with DSRC at the early stage of DSRC deployment can also reap the potential benefits of DSRC technology. A hybrid traffic information system was successfully developed; it combines DSRC technology and portable changeable message signs (PCMSs) for use in the work zone environment to improve traffic mobility and thereby driver safety. The developed system uses DSRC-based vehicle-to-infrastructure and vehicle-to-vehicle communication to acquire travel safety parameters, such as travel time (TT) and the starting location of congestion (SLoC), and to disseminate these parameters to DSRC-equipped vehicles and PCMSs, which are strategically placed along the roadside. Through the use of the DSRC-PCMS interface developed and demonstrated in this work, PCMSs can receive these travel safety parameters from nearby DSRC-equipped vehicles on the road through DSRC-based vehicle-to-vehicle communication, and display them for the drivers of vehicles that lack DSRC capability. Such a system can be useful during the early stage of DSRC deployment when DSRC market penetration is low. In addition, a rigorous analysis was conducted to investigate the minimum DSRC market penetration rate needed for successful functionality of the developed system with respect to both acquisition and dissemination of TT and SLoC. Through the use of a realistic traffic flow model, guidelines were developed to estimate a minimum DSRC penetration rate needed to deploy the developed system for a variety of traffic scenarios on a given work zone road.

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This paper focuses on evaluating, in a structured manner, the potential benefits, along with the implementation and performance issues, of utilizing dedicated short range communication-based communication in conjunction with adaptive cruise control (ACC) systems. This work was done in the United States under a cooperative agreement between the Crash Avoidance Metrics Partners LLC and the Federal Highway Administration. Designing cooperative adaptive cruise control (CACC) as an extension of ACC, and by using a combination of a comprehensive simulation framework and test vehicles, benefits of vehicular communication on string stability were established, and the performance of the novel CACC-enabling software modules were validated. Another key contribution of this work is the consideration of vehicles with different dynamic responses as a part of a single string. Four light-duty vehicles (hatchback, mid- and full-size sedans, large SUV), each from a different automotive original equipment manufacturer, were retrofitted with common ACC and vehicular communication systems. They were tested under many different conditions to obtain performance data (such as radar sensor readings, etc.) when operating in a vehicle string. These data were then integrated into the simulation environment to develop and validate the CACC modules. The paper concludes with a recommendation of some data elements for over-the-air messages to enable CACC functionality.