Texas has 80,000 miles of state highways and a rapidly growing population, but no long-term funding plan for repairing, replacing and upgrading our highway system.It's hard to imagine there's a problem when the region is awash in construction equipment and orange barrels. But the current level of construction masks a sober reality. This program has been built on a mountain of debt -- a way of funding that is completely unsustainable. And, unfortunately, the state's credit card is maxed out.Without new sustainable funding, the future of mobility in Texas looks bleak: a growing population, little money for new capacity roads, increasing congestion, more potholes, more unsafe conditions, less connectivity in rural areas and more toll roads. Actually, many more toll roads and toll lanes. If that is the only alternative left to policymakers, you can bet there will be many more.Why not let Texans vote on whether they want a different future?Legislators have relied on bonds because they don't believe voters will accept user fee increases. But voters are smart. They know that road money comes almost entirely from users in the form of gas taxes and vehicle registration fees. And they know there is no free lunch.A typical car owner who gets 20 miles per gallon and drives 12,000 miles per year currently pays about 1.4 cents per mile in registration fees and fuel fees for the state system. When you drive to Houston, you pay about $3.50 each way -- quite a bargain.Two years ago, a group of private citizens and business leaders estimated that to sustain our highway system at current congestion and pavement quality levels, the state will need to spend an additional $5 billion a year over the next 25 years. That is achievable at a cost of a few pennies per mile for drivers.Our research suggests that voters will support new user fees to build roads if several conditions are met. They want:To know with 100 percent certainty (maybe 110 percent) that revenue from new fees will actually go to build roads and not be diverted into other government programs.To make sure that new fees go to build highways with free access and are not spent on subsidizing toll roads.To have a pay-as-you-go-system of funding, moving away from debt financing and ensuring we don't pass our bills on to the next generation.To see a solution that is equitable to all road users, from heavy trucks to hybrid vehicles. The next Legislature should offer Texans a referendum on this approach by tying phased-in increases in user fees to a constitutional amendment ensuring that any new fees can only be spent on highways -- with zero money diverted for education, DPS, pensions or any of the other things we spend current gas taxes on. User fee increases would only take effect if the "no diversion" amendment passes, so voters would know that fee revenue goes to roads.There is enough planning for voters to know what projects would be built. This would be a statewide approach, not the local option of several years ago. We sink or swim together, while guaranteeing that regions get back what they pay in.What could be more conservative than giving citizens a choice about what future they want?More toll roads, more debt and more congestion? Or broad-based user fees that go to free-access roads? Why not provide a choice that will lead to a brighter Texas future?Steve Stagner is a member of Texas Future, an organization of individuals and groups involved in educating Texans on the significance of infrastructure issues.