Dive summary:

• A new study quantifies the extent to which income from gasoline taxes and user fees has fallen behind the costs of maintaining American highways, saying that spending growth that had run at a compounded rate of 6% per decade since 1950 will likely be 4.8% between now and 2022.
• SBI Energy did the analysis and published the study, which is titled, "The U.S. Road, Bridge & Tunnel Construction Market."
• Road work traditionally has been a pay-as-you-go program, but SBI says state programs are getting less than 60% of their income from user fees and taxes, and the Federal Highway Trust Fund has need congressional appropriations to stay afloat.

From the article:

For the road, bridge and tunnel construction market, the availability of public funding has been, and continues to be, a serious constraint on the market. ...