Connected Vehicle Pilot Deployment Program Phase 3, Mobile Accessible Pedestrian Signal System (PED-SIG) – New York City Department of Transportation (NYCDOT)
New York City’s Connected Vehicle (CV) technology pilot deployment aimed to support the city’s Vision Zero initiative and help eliminate injuries and fatalities caused by crashes. One component, the Mobile Accessible Pedestrian Signal System (PED-SIG) application, provides audio alerts and haptic prompts to assist pedestrians with vision disabilities in safely crossing streets at instrumented intersections. Researchers identified four signalized intersections instrumented with CV technologies and designed six routes to test the PED-SIG application in New York City. A total of 24 volunteer participants with vision disabilities were recruited for field tests conducted from October 29, 2021 to November 18, 2021. Participants were given Personal Information Devices (PIDs), which use cellular communications to receive localized Signal Phase and Timing (SPaT) status and MAP (intersection geometrics) messages broadcast by Roadside Units (RSUs). A prototype location augmentation device which can be connected to the smartphone via Bluetooth was also added to provide improved accuracy for PED-SIG.
- Beware of potential positioning inaccuracies on smart phones, and test location correction service thoroughly before deployment. The field tests of the PED-SIG application found that Global Positioning System (GPS) position accuracy remained a major challenge in an urban environment, even with the location augmentation device which used a dual band global navigation satellite system. A potential solution could involve Real-Time Kinematic (RTK) positioning or another location correction software, although these alternatives were not available natively on smart phone operating systems, and can involve additional costs. It is also important to thoroughly test any location correction services before deployment, as the project found there were locations and time periods which had better and worse performance.
- Enable real-time monitoring of the data stream connection and notifications to alert users when the connection is lost or the data transmission fails. External factors such as positioning, data streams from the Traffic Management Center, and cellular connectivity, may negatively affect PED-SIG application performance and user experience and need to be communicated with multiple stakeholders. For future deployments, real-time monitoring of data stream connection and cellular and Bluetooth connections on the smart phone is vital, along with enabling notifications alerting users of connectivity issues or data transmission problems.
- Consider weather impacts and longer vibration duration when designing mobile applications with vibration functions. Researchers observed that the experience of the vibration function was affected in cold weather, as a few participants wore thick clothing and gloves during the field tests. Moreover, compared with audio alerts, the 500-millisecond vibration (with a 2-second / 5-second gap) is less noticeable in a real-world test, as users could be distracted by many environmental factors. Therefore, a longer or more frequent vibration is recommended in the application design.
- Use containerized application development platforms for scalability, backup, migration, and data recovery purposes when managing the data extracted from the mobile application on a data server. The project team found that services which package software into standardized units is highly beneficial for scalability, backup, migration, and data recovery purposes, and can save time by avoiding the need for manually configuring the environment of the server.