Cracks discovered on I-80 bridge
Thousands of people will pour into the Quad-City area this weekend, but those using the Interstate 80 bridge that connects LeClaire, Iowa, to Rapids City, Ill., will find the going slower as the bridge is down to one lane each way for an indefinite period.
The westbound and eastbound outside lanes were closed Wednesday after bridge inspectors discovered cracks in the steel framing under the bridge deck, according to a news release issued by both the Illinois and Iowa departments of transportation.
The inside lanes of the bridge are safe and will be used, said Ralph Anderson, bureau chief of bridges and structures for the Illinois DOT, which is responsible for the bridge. He added that the lane closures are precautionary and that the bridge is sound and in no imminent danger of collapsing.
He said repair plans are in the works. The Iowa DOT will be available to provide any technical engineering assistance requested and will remain apprised of all repair plans.
The duration of the lane closures is not known at this time and will be determined based on the repair plan and work schedule.
This weekend, thousands of runners will hit the streets of Davenport for the 34th annual Quad-City Times Bix 7, while thousands of bicyclists will be pedaling into LeClaire to dip their front tires into the Mississippi River to mark the end of the 36th RAGBRAI, or the Register’s Annual Great Bicycle Ride Across Iowa.
Bruce Brakke, bridge and maintenance inspection engineer for the Iowa DOT, said the I-80 bridge, also known as the Fred Schwengel Memorial Bridge, was opened to traffic in 1965, “so it’s 43 years old. They’re designed to last longer than that. That bridge will be there a long time yet.”
What has happened, Brakke said, is that there are some longitudinal stringers, the ones on the outside lanes, on which the concrete deck lies, that are corroded and cracked at their ends where they sit on the transfer girders in weight-bearing areas.
Those longitudinal stringers run the length of the bridge, he said. “There are four under each lane spread 9 feet apart.”
The stringers have not lost their support, but they have been compromised, he said.
Anderson said that the problem occurred because every 120 feet on the bridge there is a relief joint that allows the bridge to expand and contract in the heat and cold.
“During snow and ice storms, we try our best to lay down salt and plow the snow,” he said. “Liquid brine is put on the deck during the week in the winter time, and we make sure there is a layer of salt out there. It has saved thousands of lives, but it causes accelerated corrosion for the bridges.”
At those locations where the relief joint are, there is a seal that tries to keep most of the rain and debris out, he said. But some gets down there anyway.
“There is a slope on the bridge so that it will drain off,” Anderson said. “So the salt runs off the middle of the bridge.” But it can collect on the outside on the ends of those stringers and cause corrosion and eventual cracking.
The inspectors, he said, “found the cracks on the outside stringers. That’s why the outer lanes have been closed. The inner part of the bridge is safe.”
Anderson said engineers are coming up with ideas to fix the bridge but it will not be something that is done in just a couple of days. It likely will take several weeks.
Thomas Geyer can be contacted at (563) 383-2328 or tgeyer@qctimes.com.