Safety concerns prompted the city Wednesday to close a bridge often used by buses to shuttle college students between Downtown Campus and East Campus.

The 72-year-old bridge that spans railroad tracks near 18th and Holdrege streets was abruptly closed Wednesday afternoon, after city officials said inspections showed it was in worse shape than expected.

Initial findings caused uncertainty about the bridge’s ability to handle current traffic loads, city officials said.

City officials don’t know whether the bridge will re-open.

“It’s one of those bridges that’s nearing the end of its effective life,” Public Works Director Greg MacLean said.

After a Minneapolis bridge collapsed a year ago, killing 13 people, Lincoln officials said the Holdrege bridge was perfectly safe — even though a federal bridge report deemed it “structurally deficient,” with a sufficiency rating of 35 on a scale of 100. The Minneapolis bridge’s rating was 50.

Lincoln officials said “deficient” doesn’t mean “unsafe” — as long as your vehicle weighs 26 tons or less — even though pieces of concrete were crumbling on its underbelly and rusted rebar was visible in places.

Then in June, the city hired an engineering company to study whether to replace, remove, repair or close the bridge.

That prompted a more in-depth inspection of the bridge by a structural engineering company earlier this week to determine whether trucks and buses should continue to be allowed to use it.

The extent of damaged concrete and a rust on a girder running the length of the bridge on the south side was worse than expected, prompting the city to close the southern 4 feet of the narrow bridge Tuesday night.

Officials took a look at the bridge early Wednesday, drilling holes and chipping edges, and decided to close it to vehicles, although bikes and pedestrians can still use it.

“Pieces were starting to fall off,” MacLean said. “I don’t think there’s a danger of the whole thing falling down, but certainly the railing on the south side and the southern girder are at risk.“

The last time the city put money into the bridge was in 1980, when it received minor upgrades, MacLean said.

“This is a prime example of our deteriorating infrastructure,” he said.

The results of the study should be ready in a week or two and then a decision on the bridge’s future will be made, said Randy Hoskins of the public works department.

Hoskins said traffic on the bridge has dropped from 17,300 cars a day before the Antelope Valley Project, and is now down to about 5,000 vehicles daily.

It’s possible the bridge will be re-opened to cars, but not trucks.

When the east leg of the Antelope Valley Big X bridge is done in a year or two, traffic volume on the Holdrege bridge is expected to drop more, but trains run under the bridge to a concrete plant and lumber yard — so the bridge will have to be removed, replaced or converted to an at-grade crossing.

No official detour has been set up, but most traffic is expected to move to Vine Street.

Reach Deena Winter at 473-2642 or dwinter@journalstar.com.