Applying Bundled Speed-Harmonization, Cooperative Adaptive Cruise Control, and Cooperative-Merge Applications to Managed-Lane Facilities

Ma, Jiaqi; Leslie, Ed; Ghiasi, Amir; Guo, Yi; Sethi, Sonika; Hale, David; Shladover, Steve; Lu, Xiao-Yun; Huang, Zhitong · 2021 · ROSA P / United States. Federal Highway Administration

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Summary

This report evaluates the integration of three connected and automated vehicle (CAV) applications—speed harmonization, cooperative adaptive cruise control (CACC), and cooperative merging—on managed-lane facilities. The research addresses the need to improve the operational efficiency of existing roadways by leveraging managed lanes as test beds for CAV technologies. The primary motivation is to mitigate traffic congestion, reduce stop-and-go waves, and increase throughput at bottleneck locations, such as merge areas, where traditional variable speed limits often fail due to inconsistent driver compliance. By bundling these applications, the study aims to demonstrate how vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications can optimize traffic flow, enhance safety, and reduce emissions. The methodology involved a two-phase approach: microscopic simulation and a limited field experiment. Researchers developed algorithms for CACC platooning, which reduces following time gaps from approximately 1.4 seconds to 0.6 seconds; cooperative merging, which coordinates trajectories between mainline and ramp vehicles; and trajectory-based speed harmonization, which dynamically adjusts individual vehicle speeds upstream of bottlenecks. These applications were bundled into a single vehicle-control platform. Simulations were conducted on a calibrated network to quantify potential improvements across various market-penetration rates. Subsequently, a field study was performed on a managed lane on Interstate 95 in Virginia. The experiment utilized a small number of real CAV-equipped vehicles operating in both closed conditions and mixed traffic to validate the simulation results and assess the performance of the bundled applications in real-world scenarios. The findings indicate that the bundled applications significantly improve traffic metrics compared to manual driving or isolated technologies. Simulation results demonstrated that CACC alone could increase lane capacity from 2,200 to nearly 4,000 vehicles per hour at 100 percent market penetration. When combined with cooperative merging and speed harmonization, the system further enhanced throughput and reduced delay, particularly at merge points. The field experiments confirmed the feasibility of the algorithms, showing that automated vehicles could maintain consistent speeds, form stable platoons, and execute cooperative merges with minimal impact on surrounding traffic. Data from the field tests aligned with simulation predictions, validating the effectiveness of the bundled approach in smoothing traffic flow and managing vehicle trajectories through complex bottleneck areas. The significance of this research lies in its demonstration that managed lanes are ideal environments for the early deployment of CAV technologies. The study provides a strong justification for implementing V2V and V2I infrastructure, offering tangible benefits to roadway owners, operators, and users. By improving capacity and reliability, these technologies can increase the return on investment for managed-lane facilities while reducing fuel consumption and crash risks. The report concludes that bundling these applications creates a synergistic effect that surpasses the capabilities of individual technologies, paving the way for broader adoption of connected and automated systems in transportation networks.

Key finding

Bundled speed-harmonization, CACC, and cooperative-merge applications improve traffic flow and capacity on managed lanes, with simulation and field results confirming the viability of the integrated vehicle-control platform.

Methodology

mixed_methods

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• traffic density