Report: I-74 bridge in 'good shape,' but needs work
Detailed inspection reports for the Interstate 74 bridges say both spans are in good shape, but extensive painting, recaulking and replacement of the driving surface are needed.
Reports of inspections conducted in October 2006 and in September of this year were released in full this week by the Iowa Department of Transportation following an internal discussion about what information, if any, should be made public. The September report was done in the aftermath of a fatal bridge collapse in Minneapolis, Minn.
Discussions about whether to release the reports in full revolved around concerns about making public information detailing vulnerable spots on the bridges. There were also questions about whether the spans are infrastructure critical to national security and the economy.
“We looked at the exemptions within the (Iowa) code, and there were none that allow for withholding of any portion or in whole,” said Dena Gray-Fisher, a spokeswoman for the DOT. “The bridges are joint jurisdictional. They are owned by Iowa and Illinois. We contacted Illinois to see if there was any law there that superceded Iowa law. We determined that Iowa is the custodian of those records, so we decided to release them.”
The U.S. Department of Homeland Security cautions state and local governments about the types of information about critical infrastructure that should be released but has no authority to issue “edicts” about what can and cannot be made public, Laura Keehner, a spokeswoman for the agency, said last month.
Kathleen Richardson, of the Iowa Freedom of Information Council, an advocate for open public records, said she was unaware of DOT discussions about the openness of the reports but noted that since the Sept. 11, 2001, terrorist attacks, concerns about release of information pertaining to important infrastructure has intensified.
Regarding bridges, Richardson said, many news media and others sought inspection information following the deadly collapse in August in Minneapolis.
“An unintended consequence of keeping it secret would be that the public would not see information it needs to know to determine if a bridge is safe,” she said.
The September 2007 inspection was meant to look at elements of the bridge that, if they failed, could result in collapse, said the report by Burgess & Niple, a Columbus, Ohio, engineering consulting firm hired by the state to do the examination.
The main support elements were found to be in “good” condition, but the paint on deck trusses was faded and chalking and “has begun to fail. There are areas of freckling corrosion and exposed, corroding steel throughout the structure, and pack rust of varying thickness between components is very commonplace,” the report said.
The deck, or driving surface, was found to be in “fair” condition. Chipped or crumbling concrete was found in several areas. There was also exposed reinforcing steel and areas where water leaked through to the metal superstructure.
“Paint is critical to a metal structure,” said Mark Bernhardt, director of facility inspections for Burgess & Niple. “It forms a barrier between the steel and the elements. Unprotected steel corrodes over time and can become weaker and is more likely to fail.”
The October 2006 inspection also was done by Burgess & Niple and found that “no deficiencies exist that threaten the service life of the structures.” Problems focused mainly on cracking caulk on cable bands and paint inside the tower on the Iowa-bound span that “has failed.”
“Caulk protects the steel joints,” Bernhardt said. “If it fails, water can get in the joints and cause rusting and weaken them.”
The DOT will perform some of the repairs as it does routine maintenance of the bridge, agency officials said. Other items will receive temporary fixes or monitoring until plans are made to do more comprehensive repairs.
For instance, the deck will get spot patches until there is a determination that sections have deteriorated to the point where more complete repair work is needed, said Bruce Brakke, chief bridge maintenance engineer for the DOT.
The loss of rivet heads in some areas will be monitored, Brakke said. The rivets continue to hold what they were put in place to hold, but if more heads are lost, major repairs could be needed.
The deteriorating paint on the inside of the tower on the Iowa-bound span will not be replaced, Brakke said. The metal is not being affected, and the lead-based paint would be too costly to remove.
“The caulking and some of the rust removal will be included in future repair contracts,” Brakke said. “On the cable bands, there will be a man who walks them and pours new caulk.”
Inspections
The Iowa Department of Transportation commissioned inspections in October 2006 and September 2007 of the I-74 bridges to determine their conditions. Both reports found the bridges in “good” shape, but the following problems were noted:
-- Serious paint failure and extensive rusting on some portions of the bridge.
-- Cracking of caulk on cable bands at 34 locations on the spans.
-- A few places where there is 100 percent section loss of rivet heads.
-- Numerous locations where the driving surface has deteriorated, exposing reinforcing steel and allowing water to leak through to the superstructure.
Tom Saul can be contacted at (563) 383-2453 or tsaul@qctimes.com.