Looking west on Lee Highway in Arlington, lines of cars split between taking Interstate 66 or staying on Lee during rush hour. (Jahi Chikwendiu/The Washington Post)

The Interstate 66 toll lanes opened Monday in Washington’s Northern Virginia suburbs with prices so steep they could be among the highest drivers have paid for the privilege of traveling on a state-owned highway in the United States.

Tolls in the high-occupancy toll lanes hit $34.50 — or close to $3.50 a mile — to drive the 10-mile stretch from the Beltway to Washington during the height of the morning commute. The toll reached $40 on Tuesday morning.

The lanes, on one of the region’s most congested highways, were billed as a way to help the state better manage traffic, foster carpooling and public transit use, and give commuters more options.

But whatever excitement drivers might have initially felt at having another choice quickly gave way to shock as they watched toll prices tick up — from $4.50 at 5:36 a.m. to $28.50 just before 8 o’clock to $34.50 at 8:36 a.m.

“I drove onto I-66 around 8:10 this morning to Washington and my one-way toll was $17.25 — which I at first thought I’d misread,” Justin Cole said. “With tolls reportedly climbing to around a daily one-way peak of $34.50, that is going to introduce a real hardship for people on low wages or working in the nonprofit or public sector.”

Others took to social media to express their outrage, with the hashtags #I66tolls and #highwayrobbery trending.

“This is like a bad telethon, watching the number go higher and higher all morning,” tweeted commuter Cameron Gray.

“The tolls on I-66 are being increased so only the 1% can afford to use it. Time to get that private jet,” said another.

“It’s price gouging,” said Virginia Del.-elect Danica Roem (D), who won office last month on a platform that focused on traffic in her suburban Prince William County district. She said she will push to cap tolls in the coming General Assembly session.

“We are talking about $34.50 for a few miles inside the Beltway. That’s clearly price gouging,” Roem said. “Where else in the country do you pay a $34.50 toll to go somewhere?”

Critics complained that state officials sold the project on projections that tolls would peak at $7 for the morning rush and $9 in the afternoon. State transportation officials said Monday that those projections were based on the average trip — not peak-of-the-peak trips.

“This was the very first rush hour,” said Michelle Holland, a spokeswoman for the Virginia Department of Transportation. “Every express lane facility has a ramp-up period because it is such a major change. It probably will take at least three months for us to be able to determine the typical traffic pattern and toll price pattern.”

Here’s how it works: From 5:30 to 9:30 a.m. eastbound and from 3 to 7 p.m. westbound, Monday through Friday, tolls will fluctuate to maintain a minimum average speed of 45 mph; there is no cap on tolls. Put simply, as traffic increases the toll rises to help manage the vehicles entering the roadway. The tolls change every six minutes.

Solo drivers, who before were barred from I-66 during rush hour, can use the lanes if they pay. That includes drivers of hybrid vehicles, which are no longer exempt. Motorcycles and vehicles carrying two or more people have free use of the lanes.

State transportation officials said average speeds Monday morning were 57 mph (the posted speed limit is 55), and about 37 percent of vehicles were carpools that traveled free.

Holland said state officials don’t expect tolls of $34.50 to be the norm. Rates were lower for the evening commute, with westbound I-66 drivers paying $6.25 to travel from Washington to the Beltway at 4:15 p.m.

But there’s no guarantee that prices won’t top $30 again. Monday, for example, is typically a lighter commuting day because of federal workers who telework, so it’s conceivable that tolls will rise again on days when there is typically more traffic.

Although Monday’s prices on I-66 are higher than average for U.S. toll roads, experts and transportation officials say they aren’t unheard of in an industry that generates $13.8 billion in annual revenue.

Driving on U.S. toll lanes costs drivers an average of 10 cents per mile, according to data from the Federal Highway Administration. The data, however, doesn’t include average costs from all U.S. road systems. The most expensive interstate tolls cost drivers about 50 cents per mile, and those are on relatively short lengths of road — including the 14 miles of Virginia’s Interstate 495 express lanes, where tolls have hit $32.30.

“This is the point of the dynamic pricing — it doesn’t prohibit someone from using the lane but it raises the price to keep traffic flowing and a driver considers their time, value for the cost,” said Bill Cramer, a spokesman for the International Bridge, Tunnel and Turnpike Association, which represents toll facility operators.

Some commuters and officials said those complaining about high tolls should simply choose a different option. They note that solo drivers have never been able to use I-66 during rush hour — with the exception of hybrid owners. However, the rush-hour periods were extended 90 minutes with the toll lanes. So drivers who timed their morning commutes to leave before 6 a.m. or at 9 a.m. to avoid the restrictions no longer have that option. For those in the outer suburbs, Metro and carpooling aren’t easy choices.

The I-66 lanes are unique when compared with the region’s other toll lanes, the 495 express lanes. The 495 express lanes added capacity and give drivers the option of using general travel lanes if they don’t want to pay a toll. I-66 was tolled without adding lanes.

If officials thought the tolls would encourage more people to use transit, that did not happen Monday morning — at least not for Metro. According to the transit agency, the four stations at the western end of the Orange Line in Northern Virginia (Vienna, Dunn Loring, West Falls Church and East Falls Church) had 13,239 entries during the rush-hour time frame — about 2 percent lower than the same time one week ago.

There also did not appear to be a significant amount of bailout traffic as some had feared might happen on arterial routes such as the George Washington Parkway and Routes 7, 29, 50, 123 and 193. State transportation officials said that on average, traffic volumes, speed and travel times were similar to the same time last year.

Officials are still betting that more people will turn to mass transit even if tolls don’t come close to $35 again. And toll revenue will be used for transit improvements in the corridor, including new bus routes and park-and-ride facilities.

Lori Aratani and Martine Powers contributed to this report.