Because toll prices are based on demand, it is difficult to predict exactly what the tolls will be at any given time. We expect they will range from as low as 20 cents per mile during less busy times, to approximately a $1.25 per mile in some sections during rush hour. An average trip cost is estimated to be between $5 and $6.So you work in Springfield or somewhere south of there and you want to take the new express lanes from the Tysons area to the I-95 interchange, about an 8.5 mile drive on I-495 according to a distance calculator. At $1.25 per mile, that's about $10.60 one way--and not in some distant future timeframe. The good news (if any) is Transurban says you will know what you will pay when you enter the express lanes.
That "less busy" time will be 2-3 AM I would guess.
Now add that to the future cost of tolls on the Dulles Toll Road which, I suspect, will soon (maybe as soon as next year) include peak period ("congestion") pricing to add to your toll pain. (MWAA mentioned the idea of "congestion pricing" at a recent meeting of its toll road advisory group.)
. . . OR you can take the existing free lanes on the Beltway or the Fairfax County Parkway to Springfield.
BTW, you should read the full TOLLROADnews piece. It provides good background on the new lanes, Transurban's plans, and other roads/lanes like these.
It will be interesting to see if the Beltway's tolled express lanes works as a money-making idea for Transurban. If not, of course, they will need to raise the tolls to pay their debt.