It’s ironic that the Texas Legislature, searching for a stable source of income for spending on the state’s large and growing transportation needs, turned to an anything-but-stable revenue stream: oil and gas taxes.If there’s anything Texans should have learned in the 112 years since the Lucas No. 1 gusher at Spindletop, near Beaumont, it’s that oil and gas income is not stable. It can come in big, but sooner or later it will run dry until the cycle starts again.Of course, the proposal to siphon off oil and gas tax revenue from the state’s rainy-day savings account and devote it to transportation died Tuesday along with the second special legislative session of the year.Soon afterward, Gov. Rick Perry called a third 30-day special session.Solving the state’s transportation funding problems is worth the effort. The Texas Department of Transportation has said it needs about $4 billion in additional funding per year just to maintain current highway traffic congestion levels.But reaching that goal won’t get any easier as the special session marathon drags on. The proposal to take oil and gas tax money that otherwise would go to the rainy-day fund would have generated only about $900 million a year.On Monday, shortly after House members rejected that plan, Speaker Joe Straus released a statement saying that lawmakers “have become increasingly uncomfortable with the idea of diverting and indefinitely dedicating funds away from the Rainy Day Fund to roads. These funds were never intended to be a stable, long-term way to address our transportation needs.”That won’t change in another special session.“Legislators know that Texas needs a much more comprehensive approach to funding our growing state’s growing transportation needs,” Straus said. “Until members are free to consider real options — beyond simply shuffling taxes from one purpose to another — we will not find a responsible solution to this issue.”That puts all the cards on the table. Straus is saying (out loud, even) that if Texans really want to solve their transportation problems — to get highway traffic moving more freely and add needed mass transit systems — legislators are going to have to look at new revenue sources. Sooner or later, new revenue sources means new taxes. Of course, there’s little appetite among lawmakers or their constituents for that.Gasoline and diesel fuel taxes, vehicle registration fees, motor vehicle sales and rental taxes, driver’s license fees and surcharges — all could be increased and would be stable sources of income for transportation.The transportation department also has estimated that another $1 billion a year is needed for rural roads, where truck traffic from increased oil and gas drilling has destroyed hundreds of miles of pavement. The Legislature could increase oil and gas production taxes to cover that need.None of that is likely. And if by chance it happened, Perry probably wouldn’t let it become law.The governor has criticized legislators for not agreeing on a funding measure for transportation.He said Monday’s House vote “needlessly delayed our state's ability to deal with the added strain our increasing population and surging economy are placing on our roads and highways.”He accused House members of “abdicating one of the most essential roles of state government, potentially sapping our economic momentum.” He said the plan to siphon oil and gas money from the rainy-day fund would “provide much-needed relief to working Texans everywhere who spend hours in traffic every day.”That last one was a particularly inaccurate portrayal, given that at best the plan would provide less than one-fourth the amount of funding transportation department officials say is needed just to keep those drivers in the same amount of traffic congestion they endure today.But that plan has failed, and longer-term fixes don’t seem likely. Will lawmakers throw up their hands in the third special session and vote for something so the governor will let them go home?That’s not real problem solving.