Signal Awareness Applications Signal Phase and Timing (SPaT) Data (VTTI-00-021)

Project Description: This project expanded on the current capabilities of the Virginia Connected Corridor (VCC) by development of a signal awareness application. Use of SAE J2735 standard SPaT and MAP messages pulled from VCC resources to digitally represent the connected signalized intersections along with GPS output from the mobile device was the primary source of data to enable the functionality of the Android based application. From this data, a mobile application graphical user interface (GUI) provided real-time vehicle position tracking along with the approaching intersection showing the light status and corresponding time left on the HERE map platform for Android. Upon initial development of the application, which was the primary objective, the project team investigated at a high-level, the technical and human factors (HF) performance of the application. This assessment involved researchers verifying overall application stability while also verifying that the algorithm correctly reports information such as roadway position, approach vectors, intersection SPaT configuration, and latency. Assessment involved testers traversing routes in a vehicle through SPaT enabled intersections in Tysons and Merrifield, VA while recording ground truth video of the view of the mobile application and the live roadway. This video allowed for assessment of intersection configuration and application algorithm reporting. Video was then reduced by the research team to provide feedback to developers who used to address bugs, perform improvements of the GUI, updated mislabeled roadways and update of intersection signal configurations. Technical assessment of the underlying end-to-end system network involved quantification of visual latency between what is occurring on the live roadway and what is being rendered in the mobile application, resulting in approximately 750ms of delay. Considering that the average round-trip network induced latency accounts for 140 ms, this leaves 610 ms of latency induced by a process on the mobile device. The latency on the mobile device could be improved by addressing software and hardware development factors. Data Scope: The intersection Signal Phase and Timing (SPaT) dataset used to determine network latency during testing date range of 06/30/2022 to 07/01/2022 is provided. Data Specification: Please see data specification document below.

项目说明：本项目针对弗吉尼亚互联互通走廊（Virginia Connected Corridor, VCC）现有能力进行扩展，开发一款信号感知应用。本应用的核心数据来源为从VCC资源中提取的符合SAE J2735标准的信号相位与计时（Signal Phase and Timing, SPaT）及地图数据（Map Data, MAP）消息，结合移动设备输出的GPS定位信息，以实现基于安卓平台的应用功能。基于上述数据，该安卓应用的图形用户界面（Graphical User Interface, GUI）可在HERE地图平台上实现实时车辆位置追踪，并展示途经路口的信号灯状态及剩余倒计时时长。在完成应用的初步开发（本项目核心目标）后，项目团队从宏观层面开展了应用的技术与人因工程（Human Factors, HF）性能评估。评估工作由研究人员完成，一方面验证应用整体稳定性，另一方面确认算法可正确上报道路位置、驶入向量、路口SPaT配置及网络延迟等信息。评估过程中，测试人员乘车行经弗吉尼亚州泰森斯（Tysons）与梅里菲尔德（Merrifield）境内支持SPaT功能的路口，同时录制移动应用界面与实景道路的真值视频。通过该视频可评估路口配置与应用算法的上报情况。随后研究团队对视频进行梳理分析，为开发人员提供反馈，用于修复程序漏洞、优化GUI界面、修正错误标注的道路信息以及更新路口信号灯配置。针对底层端到端系统网络的技术评估，量化了实景道路实时状态与移动应用渲染画面之间的视觉延迟，最终测得延迟约为750毫秒。考虑到平均网络往返引入的延迟为140毫秒，剩余610毫秒延迟由移动设备端的处理流程产生。该设备端延迟可通过优化软件与硬件开发环节加以改善。数据范围：本项目提供2022年6月30日至2022年7月1日测试期间用于测算网络延迟的路口信号相位与计时（SPaT）数据集。数据规范：详见下述数据规范文档。