Improving Effectiveness of HOV Facilities – Behavioral and Operational Considerations

McDonald, Mark P · 2019 · ROSA P / Tennessee. Department of Transportation

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Summary

This report addresses the operational inefficiencies and high violation rates of High-Occupancy Vehicle (HOV) lanes on Interstate 65 (I-65) and Interstate 24 (I-24) in Nashville, Tennessee. Motivated by dissatisfaction among stakeholders and the public regarding the current state of these facilities, the study aims to improve HOV effectiveness by analyzing behavioral drivers, operational conditions, and potential management strategies. The research seeks to understand why violation rates are high, how lane geometry affects performance, and what interventions could optimize corridor usage. The methodology combines behavioral analysis with advanced traffic modeling. Researchers conducted focus groups with legislative and law enforcement officials and surveyed the general public to assess perceptions, willingness to pay, and enforcement attitudes. Operational data was gathered through field measurements of speed and volume, as well as Google Traffic data. To model driver behavior and traffic flow, the study employed revealed preference analysis, stochastic user equilibrium modeling, macroscopic simulation using the Cell Transmission Model (CTM), and microscopic simulation using VISSIM. These models were calibrated and validated against field data to evaluate scenarios including "do-nothing," lane reversion, and heavy enforcement. Key findings indicate that public support for strict enforcement is lacking, and approximately one in four single-occupant vehicle drivers are willing to violate HOV restrictions. Operationally, HOV lanes suffer from poor performance due to a "sympathetic slowdown" caused by vehicles exiting the HOV lane into mixed-flow lanes at diverge bottlenecks. This late re-entry creates insufficient gaps, causing congestion in both the HOV and adjacent lanes. The study found that HOV lanes are overutilized when flow is controlled by diverge bottlenecks but underutilized when controlled by merge bottlenecks. In the peak outbound direction, where diverge bottlenecks dominate, restricting lane changes near exits via striping or barrier separation was identified as an effective strategy to mitigate congestion. The significance of this work lies in its comprehensive integration of behavioral insights with operational modeling to diagnose specific failure modes of HOV facilities. The report concludes that optimal utilization requires recruiting more vehicles to the HOV lane near merge bottlenecks while forcing re-integration at desirable locations near diverge bottlenecks. By identifying that lane change restrictions near exits can improve flow, the study provides actionable recommendations for lane management strategies that address both the behavioral reluctance to enforce rules and the physical operational constraints of the corridor.

Key finding

HOV lanes experience sympathetic slowdowns in mixed-flow lanes due to insufficient gaps for exiting vehicles at diverge bottlenecks, resulting in enhanced breakdown of both lane types.

Methodology

mixed_methods

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

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

Topics

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• traffic density