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21st Century Operations Using 21st Century Technologies

1.0 Introduction


The purpose of this report is to review the legislation and the programs in use by states allowing low-emission and energy efficient vehicles to access high-occupancy vehicle (HOV), high-occupancy toll (HOT), and managed lanes without meeting the vehicle-occupancy requirements. Information is presented on the enabling legislation, the program elements, use of the programs, and impacts on the HOV, HOT, and managed lanes. Information is also presented on the requirements contained in the Moving Ahead for Progress in the 21st Century Act (MAP-21) related to allowing these types of vehicles to use HOV, HOT, and managed lanes. The report should be of benefit to technical staff and policy makers interested in better understanding the use of HOV, HOT, and managed lanes by low-emission and energy efficient vehicles and other types of exempt vehicles.


Traffic congestion continues to be a significant issue in metropolitan areas throughout the country. Transportation agencies at the federal, state, metropolitan, and local levels are using a variety of techniques and approaches to improve traffic flow, enhance mobility, and provide travel options. Managed lanes, including HOV and HOT lanes, are approaches being used in some areas to ease traffic congestion.

HOV lanes provide travel-time savings and improved trip-time reliability to encourage travelers to change from driving alone to carpooling, vanpooling, or riding the bus. HOT lanes expand the allowed user groups to include solo drivers or lower-occupant vehicles, who can access the lanes by paying a fee. HOV/HOT lanes improve the people-moving capacity of congested freeway corridors and provide mobility options to travelers.

HOV/HOT lane applications have evolved over the past 40 years. Early projects focused primarily on bus-only facilities. Carpools became the dominate user group on most HOV lanes in the 1970s and 1980s. The 1990 Clean Air Act Amendments and the Transportation Equity Act for the 21st Century (TEA-21) expanded potential user groups to include specific types of low-emission and energy-efficient vehicles. These efforts focused on providing incentives for the purchase and use of low-emission and energy-efficient vehicles.

The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) allowed increased flexibility for state departments of transportation and other agencies in maximizing the use of HOV/HOT facilities when available capacity exists. SAFETEA-LU provisions expanded the definition of low-emission and energy-efficient vehicles to include some types of hybrid vehicles.

These provisions were continued in MAP-21, which also requires state agencies that allow tolled or low-emission and energy-efficient vehicles to use an HOV facility to submit to the Secretary of the U.S. Department of Transportation (U.S. DOT) a report demonstrating that the facility is not already degraded, and that the presence of the vehicles will not cause the facility to become degraded. Reporting that the number of permits or license plates issued is low is no longer sufficient. Agencies must monitor and certify that the HOV/HOT lanes meet the operating requirements or identify corrective action.

Agencies must also certify that they will establish, manage, and support a performance monitoring, evaluation, and reporting program for the HOV/HOT facilities. The program provides continuous monitoring, assessment, and reporting on possible vehicle impacts on the HOV facility and the adjacent highways. Further, state agencies must submit annual reports to the Secretary on those impacts. The agencies must also establish, manage, and support enforcement programs to ensure the HOV/HOT facility is operated in accordance with the requirements and that agencies limit or discontinue use of the HOV/HOT lanes by these types of vehicles whenever operations are degraded.

This requirement is a key addition – states must now certify that the HOV/HOT lanes are meeting the operating requirements, regardless of the number of low-emission and energy-efficient vehicles using the lanes. In addition, other exempt vehicles typically allowed to use HOV/HOT lanes with only the driver include police, emergency and public transit vehicles.

As of October 2013, 13 states – Arizona, California, Colorado, Florida, Georgia, Hawaii, Maryland, New Jersey, New York, North Carolina, Tennessee, Utah, and Virginia – had legislation allowing some combination of low-emission and energy-efficient, plug-in electric, or hybrid gasoline-powered vehicles to access HOV and HOT lanes without meeting minimum occupancy requirements. This report summarizes these programs. Based on experiences in the 13 states, issues and considerations with the use of HOV/HOT lanes by these types of vehicles are also highlighted.


The remainder of this report is divided into three sections. Section II provides a summary of state programs allowing exempt vehicles use of HOV/HOT lanes. These programs focus on hybrid, plug-in electric, and other low-emission and energy-efficient vehicles. It also highlights use of HOV/HOT lanes by police, emergency, and public transit vehicles with only the driver. Case studies of the states with legislation and programs allowing hybrid, plug-in electric, low-emission and energy-efficient vehicle access are presented in Section III. The report concludes with a discussion of issues and considerations with low-emission and energy-efficient vehicles use of HOV/HOT lanes in Section IV. Appendix A provides a list of references used in the report.

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