Gasoline prices are at an all time high, and as a result some areas have reported reductions in the average amount vehicle miles traveled as consumers adjust driving habits. A number of influential highway officials have seized upon this news to advocate for a move away from gasoline tax-funded transportation networks to a system dominated by toll roads.

"This latest trend is yet another reason that we need to overhaul the highway financing system," Federal Highway Administration acting head Jim Ray wrote in May. "New funding methods that are not dependent on fuel consumption are needed and needed now."

Recent data, however, show that the soaring cost of crude oil is actually hitting toll road revenue harder than it is hitting gas tax revenue. The Spanish toll road operator Cintra Concesiones announced this week that traffic on the Indiana Toll Road fell 10.2 percent in May compared to May 2007 while traffic fell 13 percent on the Chicago Skyway. Cintra blamed the drop on recent toll hikes put in place in response to dwindling traffic.

Indiana's fuel tax collections, on the other hand, have fared better than these toll roads. Simple gasoline tax receipts did drop 7 percent from $10.1 to $9.4 million between January and April 2008 as compared to the same period in 2007. But overall tax receipts in the "motor carrier and motor fuel tax" category, which includes taxes on commercial vehicles and some miscellaneous taxes, is up 9.1 percent from $285 million at the start of 2007 to $311 million so far this year.

A copy of Indiana's April 2008 tax receipts, the latest available, is available in a 20k PDF file at the source link below.