So you actually believe that the first 37,000 miles had a realistic cost of 25 Billion, then the added 9,000 miles had an acceptable cost of 89 Billion?
You really are not paying attention.
I believe that the estimated cost was realistic for the year that the estimate was made.
But the actual cost is calculated with inflated dollars which are worth less than the dollars used for the estimate.
If you don't understand how inflation affects cost estimates, then I suspect that you're too young to have suffered through the double-digit "Misery Index" of the Jimmy Carter years.