Using Connected Vehicle Data to Reassess Dilemma Zone Performance of Heavy Vehicles

The rate of fatalities at signalized intersections involving heavy vehicles is nearly five times higher than for passenger vehicles in the US. Previous studies in the US have found that heavy vehicles are twice as likely to violate a red light compared with passenger vehicles. Current technologies leverage setback detection to extend green time for a particular phase and are based upon typical deceleration rates for passenger cars. Furthermore, dilemma zone detectors are not effective when the max out time expires and forces the onset of yellow. This study proposes the use of connected vehicle (CV) technology to trigger force gap out (FGO) before a vehicle is expected to arrive within the dilemma zone limit at max out time. The method leverages position data from basic safety messages (BSMs) to map-match virtual waypoints located up to 1,050 ft in advance of the stop bar. For a 55 mph approach, field tests determined that using a 6 ft waypoint radius at 50 ft spacings would be sufficient to match 95% of BSM data within a 5% lag threshold of 0.59 s. The study estimates that FGOs reduce dilemma zone incursions by 34% for one approach and had no impact for the other. For both approaches, the total dilemma zone incursions decreased from 310 to 225. Although virtual waypoints were used for evaluating FGO, the study concludes by recommending that trajectory-based processing logic be incorporated into controllers for more robust support of dilemma zone and other emerging CV applications

Reporting Framework for Arterial-Level Traffic Signal Performance Measures Estimated from Connected Vehicle Trajectory Data

Traffic signal performance measures based on connected vehicle (CV) trajectory data can provide practitioners actionable information on the operational state of their systems. Agencies need visualization tools that can enable them to quickly assess arterial-level performance by time-of-day (TOD) to identify challenges and opportunities. This document presents a framework to report four signal performance measures over a corridor for all relevant movements, including traditional Highway Capacity Manual (HCM) level of service (LOS), arrivals on green (AOG), split failures (SF), and downstream blockage (DSB). The reporting framework can provide up to 3,072 performance data points per intersection since it provides information for eight different movements and four performance measures for every 15-minute period over 24 hours. To demonstrate implementation, 14 reports displaying performance estimations for 12 corridors, located in 11 different states, are presented. This reporting approach can facilitate the determination of possible mitigation strategies by contrasting operational conditions between movements by TOD

Extraction of Vehicle CAN Bus Data for Roadway Condition Monitoring

Obtaining timely information across the state roadway network is important for monitoring the condition of the roads and operating characteristics of traffic. One of the most significant challenges in winter roadway maintenance is identifying emerging or deteriorating conditions before significant crashes occur. For instance, almost all modern vehicles have accelerometers, anti-lock brake (ABS) and traction control systems. This data can be read from the Controller Area Network (CAN) of the vehicle, and combined with GPS coordinates and cellular connectivity, can provide valuable on-the-ground sampling of vehicle dynamics at the onset of a storm. We are rapidly entering an era where this vehicle data can provide an agency with opportunities to more effectively manage their systems than traditional procedures that rely on fixed infrastructure sensors and telephone reports. This data could also reduce the density of roadway weather information systems (RWIS), similar to how probe vehicle data has reduced the need for micro loop or side fire sensors for collecting traffic speeds

Connected Vehicle Corridor Deployment and Performance Measures for Assessment

In November 2016, the American Association of State Highway and Transportation Officials (AASHTO) announced the Signal Phase and Timing (SPaT) challenge to state and local agencies to kick start infrastructure deployments for V2I communications. The challenge involved the deployment of Dedicated Short Range Communication (DSRC) infrastructure with SPaT broadcasts (current intersection signal light phase) on at least 20 signalized intersections in all of the 50 states by 2020. Although the roadmap for agencies to partner with the automotive industry is still evolving, it is important for Indiana to not only support the SPaT challenge, but also identify mutually beneficial opportunities for INDOT to partner with the automotive industry as Indiana has the second largest automotive related Gross Domestic Product (GDP) in the country. During this study, connected traffic signal infrastructure was deployed at several locations around the state. The West Lafayette corridor SPaT message deployment was done using both traditional Dedicated Short Range Communication (DSRC) as well cellular communication. This report details the deployment locations, the various public and private sector stakeholders that were engaged during the field testing, and several vehicle-infrastructure communication experiments that were used to evaluate connected vehicle use cases. The findings of this research were as follows: The team successfully demonstrated use cases for placing virtual vehicle detection calls to a traffic signal controller using SPaT messages and evaluated latency. The team developed a scalable methodology for characterizing the probability of a traffic signal phase changing by time of day. This methodology of using agency traffic signal data for green light prediction and engine shut down at red lights is particularly useful to the automotive industry. The team successfully demonstrated that split failures, reduced roadway friction and hard braking events can be identified on the vehicle and transmitted to an agency. This enhanced probe data information is particularly valuable to agencies for identifying traffic signal timing problems, segments impacted by winter weather and location where drivers are encountering roadway conditions required hard braking. DSRC provides the lowest latency communication, but in general commercial cellular interface between vehicles and infrastructure provided acceptable latency for most use cases. For most applications, the team believes a commercial cellular interface between vehicles and infrastructure is the most scalable and feasible for an agency to maintain

Integration of Probe Data Tools into TMC Operations

With the advent of probe data, there is a need to virtualize many of the Traffic Management Center (TMC) tools used for analyzing work zones, severe crashes, winter operations, moving maintenance operations, and providing dashboards characterizing overall system mobility. Traditional tools have evolved over the past several years and it is important to develop training materials and make them more accessible to a broad range of Indiana Department of Transportation (INDOT) users and other stakeholder. Over the past several years, agencies have used probe data, mainly 1-minute aggregated segment-based probe data to assess and manage roadways. This study extended traditional segment-based probe data concepts to include enhanced trajectory-based connected vehicle (CV) data, which provides anonymous individual vehicle waypoints at a reporting interval of 3 seconds within a 1.5-meter fidelity radius. The study discusses some of the near-term opportunities, nationwide scalability, and some of the limitations of trajectory data for managing roadways and infrastructure assessment. The tools developed in this study will assist INDOT and other stakeholders in visualizing interstate queues, identifying back-of-queue hard braking events and crashes, identifying alternate diversions during incidents and road closures, enhancing agile management of work zones, estimating traffic signal performance measures without infrastructure investment, and understanding the impact of construction diversions on traffic signals performance

Connected Vehicle-Centric Dashboards for TMC of the Future

The adoption of dashboards and tools into Traffic Management Centers (TMC) has been growing with advancements in connected vehicle (CV) data. These tools are now being utilized—not only for analyzing work zones, severe crashes, winter operations, and traffic signals—but also to provide measures for characterizing overall system mobility, resiliency, and after-action assessments. Previous studies have extended the concepts to include the enhanced trajectory-based CV data into dashboards that aid agencies in assessing and managing roadways. This study presents the extension of these tools that further improve the value and insights provided. It also highlights the evolution of CV data in Indiana. CV data in Indiana has grown to over 364 billion statewide records. Average overall penetration rate of CV data on interstates has increased to 6.32% in May 2022 with trucks accounting for 1.7%. Sections of this study also present the impact of rain intensity on interstate traffic and incorporation of such weather data into heatmap and other tools. Updates to existing dashboards and a summary of newly developed dashboards are synopsized in this report. Finally, this report presents a case study that highlights the use of these tools to assess and analyze the impact of tornadoes on interstate traffic in Indiana. As interest in these tools has grown, this project facilitated continued improvements and added features to meet the needs of INDOT and their partners

Next Generation Traffic Signal Performance Measures: Leveraging Connected Vehicle Data

High-resolution connected vehicle (CV) trajectory and event data has recently become commercially available. With over 500 billion vehicle position records generated each month in the United States, these data sets provide unique opportunities to build on and expand previous advances on traffic signal performance measures and safety evaluation. This report is a synthesis of research focused on the development of CV-based performance measures. A discussion is provided on data requirements, such as acquisition, storage, and access. Subsequently, techniques to reference vehicle trajectories to relevant roadways and movements are presented. This allows for performance analyses that can range from the movement- to the system-level. A comprehensive suite of methodologies to evaluate signal performance using vehicle trajectories is then provided. Finally, uses of CV hard-braking and hard-acceleration event data to assess safety and driver behavior are discussed. To evaluate scalability and test the proposed techniques, performance measures for over 4,700 traffic signals were estimated using more than 910 million vehicle trajectories and 14 billion GPS points in all 50 states and Washington, D.C. The contents of this report will help the industry transition towards a hybrid blend of detector- and CV-based signal performance measures with rigorously defined performance measures that have been peer-reviewed by both academics and industry leaders

Statewide Screening of Signalized Intersections for Capacity Improvements

Identification of congested traffic signals that require capital investment to increase capacity has historically been a time-consuming process. Signalized intersections with congestion were analyzed to see if they could be improved through retiming, and capital investment was only considered if retiming is deemed infeasible. Automated Traffic Signal Performance Measures (ATSPMs), and more recently, signal performance measures (SPMs) derived from connected vehicle (CV) trajectory data, have already been used to streamline the process of identifying signalized intersections that can be improved through retiming. However, to date, similar efforts have not been used to identify intersections that may benefit from capital investment. This study developed a CV-based methodology to assess whether signal retiming could potentially be feasible for a given signalized intersection using the split failure percentage (SF) SPM. For intersections where retiming is not feasible, a ranking metric of critical path split failing trajectory counts (SfnCP) was developed for prioritization by capacity improvement necessity. This metric was implemented statewide to over 2,300 INDOT-managed signalized intersections over a 17-month timespan to demonstrate the effectiveness, efficiency, and scalability of the proposed approach. Additionally, the utility of CV data for similar ranking of unsignalized intersections and road segments was also discussed. To aid INDOT engineers with rapid identification and prioritization of intersections that can be considered for capital investments, performance reports containing various attributes were proposed and generated

Connected Vehicle-Centric Dashboards for TMC of the Future

SPR-4625The adoption of dashboards and tools into Traffic Management Centers (TMC) has been growing with advancements in connected vehicle (CV) data. These tools are now being utilized\u2014not only for analyzing work zones, severe crashes, winter operations, and traffic signals\u2014but also to provide measures for characterizing overall system mobility, resiliency, and after-action assessments. Previous studies have extended the concepts to include the enhanced trajectory-based CV data into dashboards that aid agencies in assessing and managing roadways. This study presents the extension of these tools that further improve the value and insights provided. It also highlights the evolution of CV data in Indiana. CV data in Indiana has grown to over 364 billion statewide records. Average overall penetration rate of CV data on interstates has increased to 6.32% in May 2022 with trucks accounting for 1.7%. Sections of this study also present the impact of rain intensity on interstate traffic and incorporation of such weather data into heatmap and other tools. Updates to existing dashboards and a summary of newly developed dashboards are synopsized in this report. Finally, this report presents a case study that highlights the use of these tools to assess and analyze the impact of tornadoes on interstate traffic in Indiana. As interest in these tools has grown, this project facilitated continued improvements and added features to meet the needs of INDOT and their partners

Scalable Operational Traffic Signal Performance Measures from Vehicle Trajectory Data

Operations-oriented traffic signal performance measures are important for identifying retiming needs to improve traffic signal operations. Enhancements on traffic signal timings can lead to a decrease on delays, fuel consumption, and air pollutants. Currently, most traffic signal performance measures are obtained from high-resolution traffic signal controller event data, which provides information on an intersection-by-intersection basis and requires significant initial capital investment. Further, maintenance of the required sensing and communication equipment can represent a significant cost. Over 400 billion vehicle trajectory points are generated each month in the United States. This high volume of data provides more than 95% of road network coverage. This thesis proposes using vehicle trajectory data to produce traffic signal performance measures such as: traditional Highway Capacity Manual (HCM) Level of Service (LOS), quality of progression, split failure, and downstream blockage. Geo-fences are created at specific signalized intersections to filter vehicle’s waypoints that lie within the generated boundaries. These waypoints are then converted into trajectories that are relative to the intersection. Subsequently, trajectory attributes, such as delay and location and number of stops, are analyzed to produce the mentioned performance measures. A case study is presented to demonstrate the methodology, which summarizes the performance of an 8-intersection corridor with 4 different timing plans using over 117,000 trajectories and 1.5 million GPS samples collected during weekdays in July 2019. Graphics to analyze entire corridors and to effectuate temporal comparisons are proposed. The thesis concludes by discussing the required effort and recommendations for scalability, cloud-based implementation opportunities and costs, reviewing current probe data penetrations rates, and indicating that these techniques can be applied to corridors with Annual Average Daily Traffic (AADT) of ~15,000 vehicles-per-day (VPD) for the mainline approaches