RSU triangulation techniques and inertial GPS solutions can improve geolocation accuracy for connected vehicles operating in dense urban environments.

New York City CV Pilot considered location correction solutions to address GPS positioning challenges associated with the cities "urban canyons"

Date Posted

Connected Vehicle Pilot Positioning and Timing Report: Summary of Positioning and Timing Approaches in CV Pilot Sites

Summary Information

The New York City Department of Transportation (NYCDOT) leads the New York City Connected Vehicle Pilot, which aims to improve the safety of travelers and pedestrians in the city through the deployment of V2V and V2I connected vehicle technologies. NYCDOT’s planned deployment provides an ideal opportunity to evaluate connected vehicle technology and applications in tightly-spaced intersections typical of dense urban transportation systems and is anticipated to be the largest connected vehicle technology deployment to date. The NYCDOT CV Pilot Deployment project area encompasses three distinct areas in the boroughs of Manhattan and Brooklyn. Approximately 5,800 cabs, 700 MTA buses, 400 commercial fleet delivery trucks, and 1,050 City vehicles that frequent these areas will be fit with the CV technology. As a city bustling with pedestrians, the pilot will also focus on reducing vehicle-pedestrian conflicts through in-vehicle pedestrian warnings and an additional V2I/I2V project component that will equip approximately 100 pedestrians with personal devices that assist them in safely crossing the street.

Lessons Learned

New York City is known for its "urban canyons" which provide a challenging environment for GNSS (Global Navigation Satellite System - a broader term including GPS and other similar systems) technology; as a result, additional techniques were required in the onboard units’ (OBUs) positioning algorithms to provide the accuracy needed for many of the V2V and V2I safety applications. Such augmentation of vehicle positioning would thus help provide continuous access to GPS positioning data so that the safety applications could continue operating while the connected vehicles passed under bridges, elevated roadways, through tunnels etc. while navigating the typical Manhattan streetscapes and traffic environment.

It was originally proposed that NYC use positioning augmentation approaches that used Radio Technical Committee for Maritime Service (RTCM) messages. The NYCDOT team considered several options and required potential vendors to consider a variety of techniques (e.g., RSU triangulation, Inertial navigation system (INS), Map Matching) to improve the overall location accuracy. These techniques were each likely to result in the need for standardization, connection to vehicle data buses, and establishment of accuracy performance requirements that consider when multiple inputs or methods are combined and address potential loss of one or more inputs.

When considering positioning correction techniques, it should be noted that the local receiver needs to be able to handle the type of corrections needed for a given method. Not all GNSS receivers are capable of using all corrections, and not all GNSS receiver and antenna combinations perform equally well under different conditions (e.g., rejection of multi-path signals). Different GNSS receivers also have varying capability to receive GNSS signals at different frequencies and from other non-GPS sources (e.g., GPS-like systems such as the Russian GLONASS or EU Galileo satellite systems). Receiving additional signals from other satellites can help to mitigate urban canyon issues since there are more potential satellites that are not blocked by buildings.

NYC eventually came to the conclusion that the urban canyon environment posed challenges to position accuracy that were of a magnitude larger than correctable by RTCM. As a result, RTCM was removed from project scope. NYC’s Onboard Unit vendors eventually decided on using a combination of RSU triangulation and inertial GPS.

As the state of positioning technology evolves over time, the capabilities, costs, and availability of solutions will change. Research is ongoing for improving positioning performance in urban environments. Currently, there are significant tradeoffs in cost versus performance, as the size of the surveying receiver market is orders of magnitude lower than the size of the automotive market. However, this has potential to change as the market changes due to automation, satellite constellation enhancements, etc.

Goal Areas

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