Opinion: High-Occupancy Toll Lanes Are a Useful Investment When Compared to Other Road Expansion Pro

Updated: Oct 18, 2021

25 years ago, the High-Occupancy Toll (HOT) lane emerged as a new transportation option. They were designed to relieve crippling traffic on America’s highways, encourage carpooling, and help the environment. HOT lanes are generally one or two lanes, usually in the center of existing highways, that drivers can only enter by paying a toll or having multiple people in their car. The price of the toll is adjusted based on traffic to keep these lanes flowing smoothly and use higher tolls to discourage new cars from joining the lanes when traffic begins to form.

All drivers who use HOT lanes must have an electronic toll transponder. Drivers who intend to carpool, and do not want to pay the toll, need a special type of toll transponder — called E-ZPass Flex in the D.C. area — to indicate whether they are travelling alone or carpooling. If they indicate that they are carpooling, an automatic camera system will photograph their car to ensure that there are multiple people in the car.

An E-ZPass Flex Transponder (Lucas Ribeiro for Lenses News)

HOT lanes are a topic of debate in the urban planning community. While they encourage carpooling and are often more efficient at transporting people than regular highway lanes, HOT lane construction projects are often paired with expensive highway expansions; this can be environmentally damaging. They also risk alienating low-income people by giving the rich an option to pay to bypass traffic without having to carpool.

HOT lanes can be expensive. For example, the 2012 14-mile 495 express lanes project in Northern Virginia cost $1.9 billion, or $134 million per mile. If applied towards other places, that money would be enough to build, for example, a light rail (tram) line, which ranges from $28 million to 182 million per mile in the U.S. Furthermore, while an HOT lane carries up to 1,800 vehicles per hour, or 7,200 vehicles in the case of this four lane project, a light rail line could carry up to 20,00 passengers per hour.

At the same time, it isn’t really fair to compare the costs of HOT lanes to tram lines. HOT lanes can often be built at no cost to governments, as they are typically built and operated by private companies, which use the toll revenue from the lanes to pay for construction and maintenance. At the same time, tram lines generally have to be funded entirely by the governments, and fare revenue usually isn’t enough to pay for their maintenance and operation.

Photo-enforcement system on an HOT lane in Northern Virginia (Image from VDOT)

Costs for HOT lanes also vary widely and depend mainly on whether the project is a conversion of existing lanes or part of a highway expansion and whether dedicated exits and entrances are built for the lanes. On the 495 express lanes project, there were no existing HOV lanes, the road was expanded, and dedicated entrances and exits for the lanes were built. This is what led to the $134 million dollar per mile price. On the nearby Northern Virginia 395 express lanes project where HOT lanes were converted from HOV lanes, the price was only $60 million dollars per mile.

HOT lanes encourage driving. If people have a traffic-free way to get to their destination, they may opt to pay the toll or carpool rather than taking public transit, biking, or walking. A study of passengers slugging (a form of carpooling where drivers pick up strangers at parking lots in order to use HOV/HOT lanes) in Houston, for example, found that most of them would have been taking transit had carpooling not been an option. While carpooling is still on a crowded highway, carpooling does result in higher per capita greenhouse gas emissions than taking public transit, biking, or walking.

At the same time, HOT lanes encourage carpooling in lieu of driving alone. While many people who use HOT lanes may have been public transit users, many others would have otherwise been driving alone. In this aforementioned study, those providing rides to the people slugging would usually have been driving alone if HOT lanes weren’t an option. People carpooling in other forms, like those who routinely go to work with a friend or family member may also have been driving alone if HOT lanes weren’t there to encourage carpooling. Because carpooling has a lower carbon footprint than driving alone, and HOT lanes encourage people not to drive alone and carpool instead, HOT lanes have a lower overall carbon footprint than a regular highway expansion, since regular highway expansions also encourage driving, but without encouraging carpooling. Overall, any additional carbon emissions from those opting to carpool rather than taking public transit is offset by the many more people who would have driven alone if carpooling hadn’t been an option.

HOT lanes reduce traffic. They can move more people through a corridor than either HOV lanes (lanes restricted to only carpoolers, with no option for paying a toll when driving alone) or conventional highway lanes. Regular HOV lanes often don’t have enough demand to fill the roads’ capacity. At the same time, conventional highway lanes often get too full, generating excessive traffic and reducing the road’s capacity. HOT lanes are built to optimize traffic flow and adjust tolls to encourage cars to enter only up to the point where traffic becomes an issue. These lanes also try to maximize the amount of high-occupancy vehicles in the corridor by giving those vehicles free tolls, which further increases the amount of people that the corridor is transporting. For example, when the I-66 corridor in Northern Virginia was converted from a regular HOV highway to an HOT highway, it began to move 700 more people per day than before. Because they can move more people, HOT lanes reduce traffic in the parallel, general purpose highway lanes.

While it may seem that HOT lanes alienate low-income individuals, this has not been shown to be the case. A study of the 495 express lanes in Virginia showed that it cost a median of $159 per hour saved in the morning, and $101 in the evening to use the lanes for those driving alone. The I-66 HOT-only road, also in Northern Virginia, can cost over $40 for a 10 mile trip for people driving alone. These high prices may make it seem like only the rich can use HOT lanes, though studies have shown this to not generally to be the case. A survey conducted on the 495 express lanes found that 60 percent of users earned less than $100,000 a year, and a study by the San Diego Association of Governments found that there was widespread support for the lanes from all income levels.

HOT lanes give people a reliable way to drive to their destination. Emergency vehicles, like ambulances, fire trucks, and police cars can use these HOT lanes to avoid traffic, which may mean a life and death difference in a critical situation. This reliability can also be important for other situations, such as for people who need to take a flight, go to an important meeting, or other time-sensitive situations.

HOT lanes can also fund transit, and make buses faster. Many HOT lane projects use tolls to pay for themselves, and some even make profit for the company or government operating them. For example, the I-66 express lanes in Northern Virginia made $12 million in revenue in Fiscal Year 2018, $5.7 million of which was profit. This profit was reinvested into transit projects in the area. Buses can also use HOT lanes, allowing them to avoid traffic and increasing their reliability.

Overall, HOT lanes are a great way to reduce traffic and encourage carpooling, especially when compared to conventional highway expansion. They can also make money by themselves, which can be useful—especially in a time like the coronavirus pandemic—when city budgets are stressed to the limit. Having HOT lanes will mean people who do not want to take public transport because of the coronavirus pandemic will have another alternative besides getting stuck in traffic on a general-purpose highway.