The Ottumwa Courier

June 28, 2013

Declining bridges to go under the microscope

By CHELSEA DAVIS
Courier staff writer

---- — OTTUMWA — Upcoming inspections will likely find what city staff already know, that some of Ottumwa's bridges are deteriorating and in need of replacement.

Four of Ottumwa's 18 bridges are up for inspection this year, three of which are ranked as "structurally deficient."

The Iowa Department of Transportation requires that "fracture-critical" bridges be inspected every five years in order to qualify for Highway Bridge Program funding.

"[The HBP] is a grant program that's based on the condition of the bridge," said Public Works Director Larry Seals. "The worse shape of the bridge, the higher it scores in the matrix."

Currently, the city is receiving $1 million from HBP for the Market Street Bridge reconstruction. A couple years ago, the Milner Street Bridge project was partially funded through HBP.

At its meeting Tuesday, the City Council will vote on an agreement to allow Calhoun-Burns and Associates to perform inspections of the Jefferson Street, Market Street, South Ward Street and Wildwood Park bridges.

Only one is fracture-critical, though: the Jefferson Street Bridge. The other three will undergo routine inspections.

"A fracture-critical bridge is one that does not contain redundant supporting elements," according to the IDOT. "This means that if those key supports fail, the bridge would be in danger of collapse. This does not mean the bridge is inherently unsafe, only that there is a lack of redundancy in its design."

Seals said the inspections are a reoccurring standard to ensure fracture-critical bridges don't develop any cracks.

According to a recent evaluation of the nation's bridges by Transportation for America, 21.2 percent of Iowa's bridges — that's more than 5,000 in total — are deficient. The report found that 29 percent of Wapello County's bridges are deficient.

Jefferson Street Bridge is "functionally obsolete," according to the report, meaning its design elements are no longer used today. But this classification has no bearing on the bridge's structural sufficiency, it noted. The bridge was built in 1936 and averages 6,800 cars per day.

"Jefferson Street gets a lot of routine maintenance and has had a couple different decks on it now," Seals said. "Part of that classification on that bridge is the construction type they used."

The Jefferson Street Bridge has two spans, he said, which means "if we lose one, the bridge collapses."

On the other hand, Market Street Bridge was ranked as "structurally deficient," meaning engineers found a major defect in its support structure or deck.

This isn't news to the city. The bridge was derated from 40 to 13 tons several years ago, so loaded firetrucks must find alternate routes over the river. The bridge was built in 1972 and also averages 6,800 cars per day.

"Most decks, you shoot for 40 years and if you get that done, then you've done a wonderful job," Seals said. "[The Market Street Bridge] deck has deteriorated as it aged, as salts go through, they deteriorate the deck and the lamination underneath begins popping off, there's exposed steel and they start losing strength.

But that's the standard process as any bridge ages, he said.

South Ward Street Bridge is also defined as structurally deficient, and the city is watching its deterioration rate closely, he said. The bridge was built in 1950 and averages 210 cars per day.

Though Wildwood Park Bridge was not included in the Transportation for America report, Seals said it's also deteriorating and will need to be replaced in a few years.

Insufficient funding is the No. 1 problem when it comes to the nation's deteriorating infrastructure, he said.

"When you look at infrastructure as a nation, we simply don't reinvest enough in our current infrastructure," he said. "We're always looking for funding sources. The bridges that qualify for federal funding we utilize when we can, but the majority of our small bridges are locally funded."

For instance, three years ago the Davis Street Bridge was rebuilt using local Capital Improvements Program funding.

The council will meet at 6:30 p.m. Tuesday in council chambers at City Hall. The meeting will air live on GO-TV, cable channel 6.

— To follow reporter Chelsea Davis on Twitter, head to @ChelseaLeeDavis.

 

County Percent of bridges deficient State ranking
Davis County 44.2 2
Van Buren County 39.6 5
Monroe County 35.2 10
Jefferson County 33.3 13
Wayne County 32.7 15
Keokuk County 30.4 22
Wapello County 29 24
Appanoose County 28.1 28
Marion County 25.9 34
Mahaska County 21 54

 

Transportation for America's website, t4america.org, has an interactive map where users can enter their address and see the status of all bridges in a 10-mile radius.