FHWA report details impact of occupancy exemptions on managed lanes

By Robbie Webber

States with high-occupancy vehicle lanes or high-occupancy toll lanes may also allow certain categories of vehicles to use the lanes without having the required number of occupants. However states are required to show that allowing these vehicles does not degrade the speed and efficiency of the managed lanes. A new report from FHWA shows the impact of these exemptions on managed lane performance.

With the exception of transit vehicles with only the driver or emergency vehicles with only the driver, the exempt vehicles are mostly hybrid-electric and alternative fuel vehicles, known as HEVs and AFVs. States give this benefit to drivers to incentivize the purchase of vehicles that will help them meet air quality standards. Each state can make its own rules as to which vehicles may use managed lanes. The states generally rely on EPA guidelines for low-emissions or energy efficiency to select eligible vehicles, and some states require a sticker, permit, or special license plate to receive the exemption.

The number of AFVs and HEVs on the road has risen sharply in the last 20 years, and the rise in hybrid sales has been especially sharp in the last 10 years. Many AFVs are commercial and fleet vehicles, while hybrid and electric vehicles have become popular with individual consumers. Besides fuel savings, some consumers chose an AFV or HEV because of the ability to avoid congested lanes or tolls. The FHWA report found several issues that states will need to consider as both managed lanes and AFVs and HEVs become more popular.

MAP-21 requires states to certify annually that allowing energy-efficient and low-emission vehicles to use managed lanes does not degrade the operation of those lanes. Both California and Virginia needed to make adjustments in their exemptions to address this degradation of service. California limits the number of stickers available for plug-in hybrids. Vehicles with electric-only motors or those operating on hydrogen, CNG, and LPG may still receive stickers. Standard hybrid vehicles, such as the Toyota Prius, hybrid Camry, Honda Insight, or hybrid Civic no longer receive an exemption. Both states also limit the exemption on certain toll roads, requiring all private vehicles not meeting the occupancy requirement to pay a toll.

Other issues highlighted in the FHWA report included problems with consumer confusion with the program, possible reduced carpooling because of exemptions, and how to treat cars from other states. Especially in New York, Virginia, and Maryland larger numbers of commuters come from adjoining states, yet the exemption is only available to vehicles licensed in the state managing the roadway. Finally, when HOV lanes are converted to HOT lanes, any exemptions from the occupancy rules means states forgo revenue from those vehicles while they still require space on the roadway. This may run counter to the purpose of HOT lanes, which is to assure a steady speed and manage congestion.

Robbie Webber is a Senior Associate at SSTI.