Illinois’ pension mess illustrates the long-term dangers of writing a short-term fix into the Constitution. Pension debt has spiraled up, but the Illinois Supreme Court — citing a constitutional provision that somebody once thought was smart — last year shot down an attempt to rein in costs.

For just that reason — so as not to tie the state Legislature’s hands in making hard but necessary choices — we urge voters to reject an attempt to write another short-sighted fix into the Constitution, a so-called “lock box” on how money from transportation taxes and fees can be spent. The amendment would require that this revenue, such as from taxes on gasoline, be spent only on transportation projects, such as repairing roads and building bridges. It could not be spent on, say, schools or social services.

It would be foolish to limit state legislators in this way, even if right now we wouldn’t trust them with our lunch money. The proposed amendment, which will go to voters on Nov. 8, would tie the Legislature’s hands for decades to come, even if our state’s spending priorities change dramatically.

Consider, for example, the very real possibility that technology in coming decades — perhaps self-driving cars — reduces the cost to the state of maintaining its roads and bridges. The state nonetheless would be unable to put the saved revenue to other purposes.

EDITORIAL

We understand why transportation advocates want the “lock box.” More than $6.8 billion in motor fuel taxes, license fees and other dedicated transportation revenues have been diverted to other uses in a little over a decade. Just this summer, Gov. Bruce Rauner and the Legislature pilfered $500 million from the transportation fund for their stopgap budget.

The raids have hurt transportation in Illinois. In real dollars, transportation revenues have declined steadily since 1991, while costs have gone up. Some 4,200 Illinois bridges and half of Illinois roads are rated in poor condition. The Regional Transportation Authority needs $19.5 billion just to catch up with deferred maintenance. The lack of investment is jeopardizing Illinois’ status as a national transportation hub.

Moreover, collecting money for one thing and spending it on another erodes public trust. Many voters remain bitter that Illinois Lottery revenues didn’t provide the windfall for education they were promised.

But good roads, airports and mass transit are not our state’s only priorities. So too are K-12 education, community colleges and universities, health care and social services, all of which are suffering from underinvestment.

The “lock box” is a popular idea. Most state legislators support the concept; a new poll by the Paul Simon Public Policy Institute at Southern Illinois University Carbondale indicates 80 percent of likely voters favor it. People want fewer potholes, not more.

But popular is not the same as wise. If lawmakers think diverting transportation money to other purposes is really dumb, they can just stop doing it.