Financing the New I-64: a 50-year variable interest rate loan

Theoretically our existing gas tax rates, both federal and state, would provide enough funding to pay for the 10 miles of the New I-64 in 50 years. For anyone complaining about “subsidizing” mass transit and talking of Metro’s “deficit”, this may be news: Interstate and highway construction does not pay for itself. We will be subsidizing these 10 miles of Interstate for 50 years. Of course by then we will be well through another rebuild.

So how did I get my numbers? Please feel free to double-check my work and challenge my assumptions:
Approximately 130,000 cars and 20,000 multi-axle trucks use this stretch of I-64. The average MPG for cars is ~22.4, for trucks, ~8. Each car will use 0.446 gallons of gasoline to drive 10 miles. Each truck will burn 1.25 gallons. Multiply gallons burned by tax per gallon and you get: $8,850 per day from trucks and $20,540 per day from cars. At that rate of “payment” it would take 18,203 days, or nearly 50 years to pay for the road (at 0% interest!). Also, cars would likely average a better MPG in exclusively highway driving, reducing the gas tax income. And this doesn’t include any maintenance, changes in gasoline income tax rates or changes in traffic counts. So a whole lot has been left out, but the gap in gasoline tax revenue and cost of road construction is apparent even for what is one of the most heavily traveled, most efficient roadways.