CHEYENNE - A year after the collapse of an interstate highway bridge in Minnesota highlighted the issue of bridge safety nationwide, Wyoming's top bridge engineer says this state's nearly 2,000 highway bridges are safe but rapidly aging.

State Bridge Engineer Gregg Fredrick cautions that roughly 1,200 of Wyoming's bridges were built between 1950 and 1970 and would need maintenance funding in the future.

"As a summary, overall, the bridges in the state of Wyoming are in very good shape," Fredrick said Wednesday. "With the age of the infrastructure, we're going to have to be cognizant of the needs and have really a steady funding stream."

Thirteen people died in the collapse of the Interstate 35W bridge into the Mississippi River in Minnesota on Aug. 1, 2007.

Marking the anniversary of the Minnesota collapse, The Associated Press reviewed repairs on the 20 most-traveled bridges with structural deficiencies in each state. The review found that only 12 percent of those nationwide have been fixed in the past year.

In Wyoming, none of the 20 busiest bridges rated as structurally deficient was permanently fixed in the last year. Two of them were partially fixed.

Fredrick said 91 Wyoming bridges, or roughly 5 percent of the bridges in the state, are classified as "structurally deficient." That term means that elements of the bridges have deteriorated to the point that they could reduce their ability to carry anticipated traffic loads.

"The fact that a bridge is structurally deficient doesn't mean it's unsafe," Fredrick said. He said the federal government requires the term be applied to bridges in order to qualify for federal funding.

Trained bridge inspectors with the Wyoming Department of Transportation inspect most bridges in the state at least every two years, Fredrick said. Some bridges, including those with posted weight limits, are inspected more frequently.

Fredrick said WYDOT spends about $200 million a year on its transportation programs, which includes about $20 million a year for structural work on bridges, retaining walls and sign structures.

That budget allows the state to replace between 12 to 15 bridges a year, rehabilitate 50 bridges a year and widen four, Fredrick said.

Of the 20 busiest, structurally deficient bridges in Wyoming, seven are scheduled for replacement in coming years, three are scheduled to be widened and rehabilitated, and one is scheduled only to be rehabilitated, according to information Fredrick provided.

In 2007, the department spent $18 million on bridge replacement projects and $7 million to widen and replace bridges, Fredrick said. He said the department expects to spend $15 million to replace bridges and $9 million on rehabilitation projects in the 2008 fiscal year.

Recent steep increases in the cost of fuel, steel, concrete and other materials have reduced the amount of roadwork that the state can accomplish each year, Fredrick said.