PHILADELPHIA, July 28 (Reuters) - One in four U.S. bridges needs to be repaired or replaced but funding is inadequate to meet the steadily rising price tag, state highway officials said on Monday.

Nearly a year after a bridge collapse in Minneapolis killed 13 people and renewed fears about the safety of U.S. roadways, the American Association of State Highway and Transportation Officials released a report saying at least $140 billion was needed to shore up 152,000 of the nation’s 590,000 bridges.

“Usually built to last 50 years, the average bridge in this country today is 43 years old and nearing the need for replacement,” the group said at its meeting in Philadelphia.

“Almost one in four bridges, while safe to travel, is either structurally deficient, in need of repair, or functionally obsolete, which means they are too narrow for today’s traffic volumes,” said the report, “Bridging the Gap.”

Costs for asphalt, steel, concrete and other materials have soared by some 50 percent the past few years, forcing many states to postpone bridge projects.

The report suggested increasing gas taxes and enacting new taxes on alternative fuels, turning free highways into toll roads and increasing private investment.

So far, regular inspections appear to have staved off most unexpected bridge collapses, the report said. The National Transportation Safety Board has attributed 47 deaths over the past 20 years to bridge failures. (Reporting by Andrew Stern; Editing by Peter Cooney)