There are plenty of reasons for outrage coming out of Washington, DC, these days, but this week the divided region found a common enemy. The express lanes on Interstate 66 near DC, previously reserved for vehicles carrying two or more people, opened up to solo travelers. Except those single-occupancy vehicles have to pay a toll, one that fluctuates according to demand. The world watched, aghast, as tolling prices hit $40 for folks headed into the capital on Tuesday morning.

Yes, that’s a crazy amount of money. But as the nation struggles to pay for its not-so-great infrastructure—and waits on the Trump administration to release a funding plan for our roads, bridges, and transit—this sort of congestion pricing is looking pretty great.

The nice thing about congestion charges isn't just that they can encourage people to take public transit, or at least to carpool, but that they make drivers pay for their role in creating traffic and spewing greenhouse gases. Forty bucks is a lot for a toll, but it just might be the fair price for the right to drive by yourself down a majorly busy highway. The scourge we know as traffic costs the American economy about $125 billion to traffic per year, according to traffic analytics company Inrix.

Places like London, Norway, Singapore, and Sweden have successfully implemented such schemes. American cities in California, Washington, Colorado, Texas, Minnesota, and elsewhere have used express lanes and congestion charges to alleviate traffic and raise extra money.

More Money, Less Traffic

OK, back to that $40 charge. Here’s how that happened. The express lane scheme that kicked in this week charges solo drivers during rush hour (between 5:30 am and 9:30 am on lanes bound for DC, and between 3:00 pm and 7:00 pm on lanes out of the city). Anyone not driving alone travels free. The price updates every six minutes, based on data collected by electronic gantries at the entrances to the lanes (more cars, more money). The charges also fluctuate according to how far you’re traveling. Travel just a few miles on the nine-mile road, and you’ll pay less money.

The Virginia Department of Transportation did not respond to requests for comment, but the agency would probably like me to note here that the $40 price lasted only six minutes before dropping to a slightly less bananas price, and that the average tolls for Monday's eastbound morning and westbound evening commutes were $10.70 and $3.80, respectively. And perhaps most importantly, traffic got better. Travel times in the area dropped by five to 20 minutes compared to the same time last year.

Those are fine results, and a bit of a reprieve in one of the country's most trafficky regions. But transportation policy specialists say you need to give this kind of express lane time to do its works on commuters’ brains. In other words: It’s too soon to be shocked.

“Transportation pricing usually takes several months or even years to achieve its full effects, so the current maximum prices are probably two or three times what will occur once everybody becomes familiar with the system,” says Todd Litman, executive director of the Victoria Transport Policy Institute in British Columbia. “Over the next few months, many travelers will probably change when and how they travel, so the maximum price will probably decline to a few dollars per trip.”

One of congestion pricing’s greatest strengths is convincing drivers to skip trips they don’t really need to take, or convince them to go at another time. Though the express lane scheme targets commuters, not everyone who travels during those periods is going to work. In fact, some might be taking totally optional trips—grabbing milk, meeting a friend for coffee. “The percentages vary by metro area and travel corridor (as do the timing and duration of peak periods) but the data show that about half of peak period trips are for other purposes,” says Elizabeth Deakin, who studies regional planning at UC Berkeley and has evaluated congestion tolling in the Bay Area.