Federal transportation officials have given Missouri officials the green light to rebuild Interstate 70 across the state to include lanes only for trucks. That’s the good news.

But there are a couple of hitches.

The project is expected to cost about $4 billion. Where would the money come from?

And even with lanes separating trucks from regular vehicles, there still will be safety issues.

But let’s not get ahead of ourselves. The idea is a sound one. Interstate 70 between Kansas City and St. Louis has been overcrowded for years, a corridor known for an overabundance of semis and vehicles traveling much faster than the 70 mph speed limit. The project recently approved by the federal government calls for trucks in the two inside lanes in each direction, with a grass median separating them from other vehicles. Cars, motorcycles, pickups and SUVs would travel in two outside lanes in each direction.

As a first step, Missouri plans to seek $200 million in federal stimulus money to build the truck lanes on 50 miles of interstate in Cooper and Saline counties. That segment would test the concept while the state tries to find funding for the larger project.

State Sen. Bill Stouffer, R-Napton, chairman of the Senate Transportation Committee, has suggested raising the money with a statewide 1-cent sales tax. He projects that would raise enough money to rebuild not only I-70, but also Interstate 44.

The Kansas City Star, meanwhile, has suggested a toll-road approach. Let those who really want to use the road pay for it, the newspaper reasons.

Neither idea is perfect. The 1-cent tax may be hard to sell in this economy, especially in areas not directly affected by I-70 traffic. And although we like the idea of pay as you go, we’re wondering how independent-minded Missourians will take to the idea of a toll road. The General Assembly would have to approve a constitutional amendment and submit it to voters.

Further, anyone who has driven in harrowing I-70 traffic knows that semis are only part of the problem. A larger challenge is posed by drivers, many in oversized pickups and SUVs, who act as if they’re training for the Indy 500 — weaving in and out of traffic, cutting off other drivers, coming up behind you suddenly at speeds up to 90 mph and slamming on the brakes. They get away with it because the state generally is lax in enforcing the 70 mph speed limit.

Truck lanes won’t stop that. A little more enforcement by the Highway Patrol would help.

Still, truck lanes for I-70 are a good idea, and officials should pursue the concept — assuming they can find a way to finance it.

Meanwhile, remember that U.S. Highway 36 and U.S. Highway 50 also traverse the state from west to east. If you’re looking for fewer big trucks and a little slower traffic, they offer a nice option. Sometimes the roads less traveled are the ones most interesting.