Missouri highways have taken a turn for the better, a new study concluded. And that could prove costly.

The Reason Foundation's 19th annual Highway Report ranked Missouri No. 8 among states for its overall highway performance. The study measured things such as the condition of bridges, urban interstates and rural highways, as well as fatality rates and maintenance spending.

Missouri ranked No. 24 the previous year. Illinois ranked No. 40 in the most recent report.

"You noticed in the report a big step up from last year," said David Hartgen, the study's lead author and an emeritus professor of transportation studies at the University of North Carolina at Charlotte.

Hartgen, who has driven through Missouri a number of times, said the rural interstate highways have been largely repaired and the condition of even the urban interstates around St. Louis and Kansas City are in the top one-third nationally. Missouri also ranked No. 10 in highway disbursements.

On the flip side, Missouri still ranks 40th in functionally obsolete bridges and 38th in narrow rural lanes.

Ed Hassinger, the St. Louis district engineer for the Missouri Department of Transportation, said the study 'shows you what an investment in transportation will do."

Missourians have committed significant funding to highways following the passage of Amendment 3 in 2004, and most recently MoDOT has taken aim at shoring up bridges around the state. What's more, the Reason study was based on 2008 data — before rebuilt Highway 40 reopened and before an infusion of federal stimulus dollars in 2009 and this year.

"Those two years were heavy investment years," Hassinger said.

What belies this rosy picture is that Missouri's highway funding is starting to dry up, transportation officials warn. That means the momentum toward better highways and bridges could wane — even while studies like this one show the state's road conditions are on the mend.

There's concern that it could become more difficult to drum up public support for taxes or other means of financing future highway projects. Reviews like the Reason study can become a sword that cuts both ways, even its author acknowledged.

Bill McKenna, a former state senator and highway commissioner, acknowledged that it's a conundrum.

The combination of Amendment 3 money and federal stimulus dollars has allowed MoDOT for the past six years to do a lot of things that it wanted to do for many years, said McKenna, chairman of the Missouri Transportation Alliance. His group is looking at how to generate funds to keep things going, probably about $700 million a year.

"It's hard to convince people that they have to invest more in infrastructure when they see things are pretty good," McKenna said.

Q. In the last several years, I've noticed that many bigger intersections in the St. Louis area have a sign over the right-turn signal that says, "Right turn signal." Many times, people misunderstand this sign to mean that if the right-turn signal is red, they can't turn right until the light is green. I know this because I am constantly behind these people. I believe that if the signs were replaced with something less ambiguous, such as "right-turn yield on red," people would not be confused and would go ahead and turn if the coast was clear. Or how about just getting rid of the "right-turn signal" signs?

— Gina Parsons, St. Peters

A. This is a common source of heartburn — and confusion — for local drivers. The signs were posted on larger intersections to actually prevent confusion, said Missouri Department of Transportation spokeswoman Linda Wilson. Say there is an intersection where you can turn right, go straight or turn left. On larger intersections where the right-turn lane is set off by a wedge-shaped island, the traffic turning right could actually have a green light while the traffic traveling straight or left has a red. That said, MoDOT is reviewing the sign wording, and has actually removed some of the "right-turn signal" signs, she said.

Q. Regarding your question/answer items, I want to know where Spirit of St. Louis overpass is. If it is in Chesterfield, I grew up there and we know where the Spirit Airport is but not any overpass thus named.

— Unsigned

A. Spirit of St. Louis Boulevard crosses Highway 40 between North Outer 40 (to the north) and Chesterfield Airport Road (to the south). If you are driving toward St. Charles, it crosses over the highway west of the Long Road overpass. Last year, the city and a developer paid to have the longstanding bridge turned into an interchange, MoDOT officials said.

Q. When will the responsible party repair the railroad tracks at Big Bend and Geyer? They are in terrible shape. You could drop a muffler system because of them.

— Ann Gavin

A. On Sept. 19. That's when the Burlington-Northern Santa Fe Railroad will start a six-day project to replace the crossing at Geyer, a company spokesman told us last week. The old rubber crossing material will be replaced with a concrete pad. Signs alerting motorists to the rough crossing should go up Sept. 12, the spokesman said. Kirkwood Public Works Director Todd Rehg said the city pushed to have the work done while St. Louis Community College at Meramec was on break, but it didn't work out. When the work is complete, Rehg said, "It will be 10,000 times better than it is now." Burlington Northern is expected fix the Big Bend crossing next year, he added.