Lab-Test Results Showed that Vision-Based Red Light Violation Warning Application Combined with Assured Green Period Could Reduce Red-Light Running by 93 Percent.
Researchers Assessed Safety Impacts of Connected Vehicle-Based Applications Interfacing with Roadside Signal Equipment using Hardware-in-the-Loop Simulations in a Laboratory Situation.
,Florida,
Assessment of the Infrastructure Readiness for Connected Vehicle to Infrastructure Applications on Arterial Streets
Summary Information
An important feature of Connected Vehicle (CV) applications is their capability to support various road infrastructures to enhance mobility and safety of the transportation system. This study developed specifications for the CV Roadside Equipment (RSE) required for communications between the infrastructure and road users, focusing on the hardware and communication aspects of these RSE. It developed message level requirements of three CV applications: (i) Red Light Violation Warning (RLVW) utilizing Signal Phase And Timing (SPaT) and Map (MAP) messages, (ii) Emergency Vehicle Preemption (EVP) using Service Request Messages (SRM) and Service Status Messages (SSM), and (iii) Work Zone Warning (WZW) and Reduced Speed Zone Warning and Lane Closure (RSZW/LC) using Traveler Information Messages (TIM). In addition, test plans for the CV-based applications were developed to verify the completeness and accuracy of the format of the data produced by the RSE. The study also built a laboratory scenario for testing of RLVW, using hardware-in-the-loop simulation (HILS) with and without the provision of Assured Green Period (AGP) design feature on the actuated controller, to compare the number of Red Light Running (RLR) events, as well as right angle and rear-end conflicts.
METHODOLOGY
The test plan for three applications considered two RSE configurations: one using FHWA's open source V2X Hub middleware, the other relying on built-in RSE features. Two data capture methods were employed: wired connection and wireless packet capture. This study also conducted a HILS by integrating traffic simulation software and a physical traffic signal controller for a typical four-leg intersection model to test the performance of the CV-based RLVW application for through-movement vehicles only. The number of RLR events, as well as right angle and rear-end conflicts, was compared for the CV-based RLVW application with and without including the AGP design feature, which typically mitigated the issue with the uncertainty in the provision of the end of the green time in SPaT messages with actuated signal control. The AGP extended the green for the phase serving the approaching CV vehicles and was calculated based on the approach speed and distance from the stop line.
FINDINGS
- The results showed that the combination of the CV-based RLVW application on the on-board equipment and the AGP on the actuated controller could reduce the overall intersection RLR by 92.5 percent, from 8.3 to 0.7 RLR events per hour, at 100 percent CV utilization rate.
- When comparing the cases with and without applying the AGP in combination with the CV-based RLVW application with 100 percent CV utilization rate, the number of right-angle conflicts was reduced by 95 percent, from 9.3 to 0.5 conflicts per hour.
- When comparing the cases with and without AGP, the results showed that the number of read-end conflicts decreased by 100 percent, from 20 to zero conflicts per hour, respectively, both with the CV utilization rate being 100 percent.
- However, the results also showed that the application of the AGP could increase stopped delay, number of stops, and approach delay, which requires further research to determine the optimal setting of the AGP for mobility and safety impacts.
