Sounds like DC has a population control problem. Around here we issue hunting permits when the animals are overbreeding without enough natural predators.
There’s a very easy way to get lots and lots of cars off the roads. Incentivize working from home. Any business that the jobs don’t require being present at an office who builds one and makes people go drive to it and sit in it for no reason, gets fined (or alternatively a business who goes all WFH get a tax break, same thing).
Better ROI on changing energy use and then also on traffic, than all sorts of other silly “green” initiatives.
Same thing with companies who require travel for meetings that can be accomplished via videoconferencing. Airline lobby will lose their freaking minds, but if you want to burn hundreds of thousands of fuel every day... oh the oil lobby will also lose their minds.
It doesn’t have to have any more than a 20-30% impact to be immense.
The Feds do have flex work, and a number of companies do. DC also has the subway. "Flex Work" includes telework and flexible hours (some are on longer days with one more day off every 2 weeks, some come in as early as 6:30 AM and leave by 3, a fair number work from home but there is concern that some "cheat" on their hours.
The roads, however, were designed back in the 60's and 70's when the region was about half to a third the population it is now. It's so bad that the housing prices are high (the realtors have a saying "drive 'till you qualify", meaning you have to go further out to get affordable housing) and the public transportation systems are not great, so there are a lot of folks on the road. There are 4 roads with the worst traffic: I-66 in Virginia, I-95 in Virginia, the Beltway in Maryland, and I-270 in Maryland. I-66 and I-270 are "spokes" from areas that now have far more population - and they're jammed. Virginia widened their stretch of the beltway (albeit with PPP toll lanes), but Maryland refuses so there are huge backups at the river crossings where the number of lanes change. The Beltway has been widened twice in Maryland and 3 times in Virginia since it was first built. I-95 in Virginia carries not only commuters to DC but also all the north-south traffic on the East Coast. There have been plans for an outer Beltway/bypass since the 70's - Maryland and the NIMBYs refuse to consider it on their side.
One would think that the logical solution would be to increase/charge taxes and proffers on the developers of real estate to build roads and infrastructure - they pay some money, but the developers & businesses have fought tooth and nail against the proffers so they are limited.
The cities and counties are pushing "transit oriented development", and new building construction has a much lower parking requirement - the intent by the cities and counties is that by reducing available parking it will reduce the number of people driving. Uber & other services are big. ZipCar has a strong presence.
WFH and hoteling are big. A friend of mine is building a business around short-term office use. I can't even count the number of Regus facilities. CO-working space is also big. I work from home and maintain a membership in a business club for when I need to have meetings. But a neighbor works with certain critical government communications systems and must go into the office each day. Likewise a good friend that has a support role for a law firm.
Remember the city is packed with government offices, law firms, lobbyists, and other professional businesses that interact with the government (consultants that deal with the FCC on behalf of companies is an example). Plenty of trade organizations here - some like AOPA are in the deep suburbs, but others are closer in. And some - like NRA - were further out until the city grew out around them. But "work from home" is not an option if one's job deals with classified information.
What may seem like a simple solution really is not. Yeah, variable tolls tend to affect traffic on the arteries they apply to, but that pushes folks to city streets. The Metro system sucks. It shouldn't, but it does (that's a chapter of the story by itself). With the push to "mixed use", we've got more residential in areas that used to be business - with a corresponding problems appearing on reverse commutes. In fact, a number of large businesses are now outside the city, making public transit options less effective.
And all that doesn't consider the tourists.
You got it a lot easier out where you live.