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Section 1: Introduction

High-occupancy vehicle (HOV) lanes are reserved for vehicles with a driver and one or more passengers. In some cases, other vehicles are also exempted (permitted in the HOV lanes).  Examples include motorcycles, transit and charter buses, emergency and law enforcement vehicles, low emission vehicles, hybrid or alternative fuel vehicles, and/or single-occupancy vehicles (SOVs) with a toll. These lanes, which usually run parallel to general-use highway lanes, have been implemented in over 30 US metro areas since they first appeared in the late 1960s and early 1970s. HOV lanes were originally conceived as a means to encourage carpooling and therefore increase person throughput in the transportation system, among other potential benefits like providing reliable transit trip times and increasing roadway capacity while benefiting air quality. The restrictions in these lanes limit traffic demand, which can provide travel time savings along a corridor when compared to adjacent general-use lanes. This travel time advantage is an incentive to drivers to form carpools in order to bypass congestion. Today, there are nearly 350 HOV facilities operating or planned across 20 states.

Unfortunately, HOV lanes do not always provide the expected advantages. Situations frequently arise in which the facility operates with too many (or too few) vehicles during lane operation periods, leading to a number of potential problems. Empty-lane syndrome, the popular term for a condition in which HOV lanes are underutilized, is one common concern. Peak-hour congestion in HOV lanes is another. Striking the proper utilization balance is a challenge for all HOV operators. Add to that the issues that stem from peak directional flows, and the efficient operation of HOV facilities becomes even more complicated. Agencies seeking to avoid or mitigate these lane performances problems will often consider and implement HOV lane policy change as a solution. .

Not all policy changes are motivated by operational difficulties, however. Other motivations for such change include maximizing system throughput, revenue generation (in the case of high occupancy toll (HOT) lanes), and legislative mandate. Opportunities for getting more vehicles through a particular corridor almost always exist, and changes to HOV policies can help to realize throughput gains. Implementation of tolling on HOV lanes can also provide revenue for lane maintenance or expansion, transit improvements, or other purposes in the region. Legislation can also drive policy change. HOV operators are currently required to consider policy changes if average speeds in the HOV lanes drop below 45 mph for 90 percent of the time over a consecutive 180-day period during the weekday peak periods (23 USC. 166 (d)(2)(B). And some operators have had to adjust their policies based on laws that allow hybrid vehicles to use the lanes without charges. Finally, Federal initiatives, such as the Value Pricing Pilot Program and the Urban Partnership Agreement, encourage pricing experimentation and have in some cases included policy changes to existing HOV lanes to serve as tests leading to wider implementation.

This study examined the performance of HOV lanes with regard to the goals and objectives under which existing HOV lane facilities were deployed. Also addressed are factors that can best contribute to the success of HOV lanes, through targeted and focused outreach to HOV operators. Identification and improved understanding of these factors can contribute to effective policy change decisions that improve performance of existing and future HOV facilities.

The study consisted of the following four tasks:

  • Task 1: Prepare a Detailed Work Plan.  This task involved conducting a project kick-off meeting and preparing a detailed work plan that articulates the approach and strategies employed to achieve the study’s goals and objectives. The work plan outlined key topic areas and described an overall approach to assembling the information critical to understanding the relationship between operations, policy, and performance.

  • Task 2: Assemble Available Data and Perform Analysis of the Performance of Existing HOV Lanes in the United States.  The purpose of this task was to develop an understanding of HOV lane success factors and what forces will raise expectations of HOV lanes in the future.  This task consisted of the following subtasks: Conduct Inventory of HOV Programs and Operations; Develop Screening Criteria for Identification of Critical Partners; Assess the Performance of HOV Investments; and Prepare Task Documentation.

  • Task 3: Assemble Available Performance Data and Analyze the Impacts of Increasing Occupancy Requirements.  The purpose of this task was to develop a policy options evaluation tool in order to quantify the effects of HOV policy changes on operational performance and measures of financial feasibility.  This task included the following subtasks: Organize and Consolidate Critical Success Factors; Develop Policy Drivers and Performance Targets; Develop Policy Options Evaluation Tool; Use the Policy Options Evaluation Tool to Quantify the Impacts to Operational Performance and Financial Impacts; Establish Relationships between HOV Lane Operating Performance and Policy Drivers; and Prepare Technical Documentation.

  • Task 4: Final Documentation.  This task involved packaging the main study outcomes into a Draft Final Report for FHWA review, then a Final Report that incorporates comments received.

The remainder of this report is organized according to the following sections:

  • Section 2: Operational Description of the Nation’s HOV Lanes.  Contains summary information from the HOV Lane Compendium, prepared as a deliverable for Task 2, documenting the basic characteristics of current and proposed High-Occupancy Vehicle (HOV) lanes throughout the United States.  This includes information on the number of facilities, date opened and status, operating characteristics, and operating performance.

  • Section 3: HOV Lane Operator Survey Results.  Provides findings from an online survey of HOV lane operators and in-depth interviews with a subset of HOV facility critical partners to discuss their experiences, challenges, and success factors.  This includes information on system goals and objectives, performance monitoring, HOV system performance, plans to revisit goals, HOV lane operational policies and policy changes, policy change motivations, and policy implementation success factors.

  • Section 4: Policy Options Evaluation Tool.  Describes the Policy Options Evaluation Tool for Managed Lanes (POET-ML), developed to help HOV owners consider a range of potential HOV lane policies including changing occupancy requirements and managed lane pricing.  This includes information on the tool’s purpose, framework, user inputs, and evaluation of potential impacts.

  • Section 5: Conclusions.  Provides the characteristics and lessons learned that increase the chances for successful implementation of HOV lane policy changes.

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December 2008