Deficiencies found on Highway 965 bridge over Iowa River

Structural deficiencies on Johnson County's Highway 965 bridge over the Iowa River have forced officials to place immediate weight restrictions on the structure.

Plans also are in place to reduce traffic to a single lane on the bridge — which, according to the Iowa Department of Transportation, carried more than 1,800 daily vehicles in 2014 — until the majority of the structure is replaced.

Rob Winstead, assistant county engineer with the Johnson County Secondary Roads Department, said the deficiencies were found on Wednesday by county maintenance employees performing normal updates on the bridge.

A structural engineer — the county contracts with Coralville's VJ Engineering — inspected the bridge that night and determined the connection had been compromised between the bridge's deck and beams, which are supposed to act as one. That separation can speed up deterioration, Winstead said.

'In order to prolong the life of that deck, such that we don't have to completely close it down, we're getting traffic off the Southbound lane and getting the heaviest of heavy trucks off that bridge totally,' Winstead said.

Winstead said the weight restriction and lane reduction is to prevent further damage to the bridge, but added that the structure is not unsafe.

'If there was any danger, that whole bridge would have been closed immediately,' Winstead said. 'People shouldn't be afraid to drive on that bridge.'

The 450-foot-long bridge was last inspected by a structural engineer in August 2014 — bridge's are regularly inspected every two years — and the structure was recommended and slated for a 2018 replacement on the county's Five Year Road Plan.

'This wasn't completely an unplanned thing,' Winstead said. 'For some reason the deterioration has advanced such that we now want to tackle that project sooner than 2018.'

The Johnson County Board of Supervisors on Thursday held an emergency meeting to discuss the bridge's deficiencies and form an action plan. The board expects to revisit the topic at a meeting next week.

On Thursday, board members approved a resolution to place weight restrictions on the bridge at a maximum weight of 20 tons. Efforts were being made Thursday to close the bridge's southbound lane and set up temporary traffic signals so only one direction of traffic can cross at a time.

While it doesn't pose an immediate danger, reducing the bridge to a single lane does impact traffic and, with ongoing work taking place on nearby Interstate 380, Highway 965 has been seeing more vehicles recently, said Tracey Mulcahey, North Liberty assistant city administrator.

'Highway 965 is a great alternate route to I-380. This will slow things down,' she said.

Johnson County Supervisor Janelle Rettig said her first concern Thursday was public safety, but her second was on finding out how the bridge's repair needs jumped ahead by two years.

'I am concerned that with structural engineers and bridge inspectors and our own engineers, how something can go from 'No problem, you can do it in 2018,' to a crisis,' Rettig said. 'I just find it very disconcerting, I find it disappointing and beyond this one project I want to figure out how that happens.'

Supervisor Rod Sullivan said the next step is determining what fixes the bridge needs, which could involve discussions with Iowa DOT.

'We knew we had work to do on it. We didn't know it would be quite this bad,' Sullivan said.

Winstead said work to replace the bridge could cost as much as $2 million. Other specifics, including a timeline, have not been determined yet, he said.

Supervisor Mike Carberry said issues on the Highway 965 bridge showcase a common theme across the country.

'This is really an emergency situation,' Carberry said. 'Our roads and bridges in this country are dilapidating.'

As for Iowa, an aging bridge infrastructure is commonplace, according to a 2015 National Bridge Inventory report released earlier this year. The report, which used Federal Highway Administration data, found that Iowa ranks first nationwide in terms of the total number of deficient bridges and third for the percentage of deficient bridges in a state's overall inventory.

Of Iowa's 24,242 bridges, 5,025 of them — or nearly 21 percent — are considered structurally deficient, according to the report.

Structurally deficient bridges aren't inherently unsafe, but possess elements such as the deck, superstructure or substructure that are in poor condition or worse.