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Improving Effectiveness of HOV Facilities – Behavioral and Operational Considerations

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English


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  • Creators:
    McDonald, Mark P
  • Corporate Creators:
    Lipscomb University (Nashville, TN)
  • Corporate Contributors:
    Tennessee. Department of Transportation
  • Subject/TRT Terms:
  • Publication/ Report Number:
    RES 2017-01
  • Resource Type:
    Tech Report
  • Geographical Coverage:
  • Edition:
    Final report covering 2/1/2018 to 8/30/2019
  • Corporate Publisher:
    Tennessee. Department of Transportation
  • Abstract:
    This report documents and details the work done on Project RES 2017-01, Improving Effectiveness of HOV Facilities - Operational and Behavioral Considerations. In this project, the problem of the extremely high violation rates in Nashville’s High Occupancy Vehicle (HOV) lanes is considered. Specifically, the project seeks to: (1) document the current operational conditions on Nashville’s HOV lanes; (2) understand the values and perceptions of key stakeholders through focus groups held with legislative and law enforcement officials and through a survey of the general public; (3) quantify the choice behavior of the driving public through analysis of revealed preferences of drivers; (4) perform user equilibrium modeling to explore the sensitivity of mode and lane choice decisions; (5) perform macroscopic simulation using the Cell Transmission Model to solve the Lighthill-Whitham-Richards Partial Differential Equation, coupled with relationships of the speed in the mixed-flow and HOV lanes to the speed of all vehicles, obtained from field data; (6) construct, calibrate, and validate VISSIM models for traffic microsimulation to explore operations on the HOV corridors; and (7) evaluate the effectiveness of various lane management strategies for the HOV corridor. It was found that in general, people in Middle Tennessee are dissatisfied with the current operational state of Nashville’s HOV lanes. Violation rates are very high and do seem to detract from some users’ experience of the benefits the HOV lane should be able to provide. However, the public will to enforce HOV lane restrictions in their current form is lacking, as is the ability of the Tennessee Highway Patrol to enforce HOV lane restrictions in any significantly impactful way. Operationally, the HOV lanes suffer poor performance even under relatively lighter volumes than the mixed-flow lanes carry. The close correlation between speeds in the HOV lane and the mixed-flow lanes is observed in field speed data. Microsimulation allows the cause of this sympathetic slowdown as a result of vehicles in the HOV lane having insufficient gaps to re-enter the mixed-flow lanes. The late entry into the mixed-flow lane of vehicles exiting the HOV lane results in the enhanced breakdown of both the HOV lane and the mixed-flow lanes in the vicinity of diverge bottlenecks. The ideal utilization of the HOV lane depends on many factors, but most importantly, whether flow is being controlled by merge or diverge bottlenecks. In general, HOV lanes are over utilized when flow is controlled by diverge bottlenecks but are underutilized when flow is controlled by merge bottlenecks. As flow into Nashville is controlled by both merge and diverge bottlenecks, more vehicles need to be recruited to the HOV lane in order to achieve optimal usage of the highway in the vicinity of the merge bottlenecks, while forcing the re-integration of the vehicles that use the HOV lane into the mixed-flow lanes at desirable locations for the entire corridor. In the peak direction (i.e., out of Nashville), the flow is primarily controlled by diverge bottlenecks. These bottlenecks can be improved by restricting lane changes from the HOV lane in the vicinity of the bottleneck by striping or by barrier separation.
  • Content Notes:
    Date on cover: March 6, 2020 (Revised March 8, 2021)
  • Format:
    PDF
  • Funding:
    RES 2017-01
  • Collection(s):
  • Main Document Checksum:
    urn:sha256:2220775f7117427db928528df41cb857f76c017ba04d712db81a2243b3fa11bf
  • Download URL:
  • File Type:
    Filetype[PDF - 15.75 MB ]
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