Last week Sec. Ray LaHood suggested that tolling and an infrastructure bank could supplement current gas tax revenue to fund a multi-year surface transportation bill, and repeated the Administration's opposition to a fuels tax increase.

There are some challenges to that approach however.

Most Congressional members are cool at best (and many are outright opposed) to expanding tolling. And neither the House or Senate provided funding for the infrastructure bank in the draft FY 2011 bills.

There are some other challenges. Tolling often works best for the largest projects in urban settings; smaller urban and rural projects in particular are probably disadvantaged by a tolling approach. And how would tolling benefit stand-alone transit, commuter and passenger rail projects, and livability projects? Perhaps USDOT believes those projects could be funded through the existing revenue stream and the infrastructure bank; that's a reasonable proposition, although a chunk of the current revenue stream is used for preservation and maintenance of the existing system.

In spite of the possible challenges, LaHood deserves credit for proposing some funding ideas, and keeping alive the authorization conversation.