Ensuring safe spans

Monday, August 20, 2007
Highway 51-60-62 Ohio River bridge at Cairo, Ill. (Fred Lynch)

Starting this afternoon, the bridge carrying drivers on Highway 51 from Perry County to Chester, Ill., will get a detailed inspection.

Traffic will be reduced to a single lane at times during the work, which Missouri Department of Transportation officials expect to finish Wednesday.

The Chester bridge is one of 11 in Missouri with a design similar to the I-35W bridge that collapsed earlier this month in Minneapolis. The two bridges have one thing in common: a steel-truss design by the engineering firm Sverdrup and Parcel. The St. Louis-based firm was bought in 1999 by Jacobs Engineering Group (now Jacobs Technology).

MoDOT inspectors, who made visual appraisals of state bridges after the Minneapolis collapse, will get a close-up of Chester, using a "Snooper" truck. The Snooper uses a cranelike arm and platform to move inspectors along the underside of a bridge as well as above it.

The Mississippi River bridge at Chester, Ill., is similar to the one that collapsed earlier this month in Minnesota. (Fred Lynch ~ flynch@semissourian.com)

Mike Helpingstine of MoDOT's District 10 office in Sikeston said bridges are typically inspected every other year.

Interstate bridges, such as Chester and the two leading from Mississippi County to Cairo, Ill., are inspected by transportation departments in both states every other year, "unless we find something that gets our attention," Helpingstine said. "Structurally deficient means it won't necessarily hold the legal limit of the load, 80,000 pounds. We might want to post it at 60,000 pounds ... it's not that it's unsafe or unsound. It's just not up to currently design standards."

He said no major projects are underway on any Southeast Missouri river crossings.

At the same time engineers are inspecting the Chester bridge, lawmakers are convening in Jefferson City for a special session called by Gov. Matt Blunt. He wants to kick-start MoDOT's Safe and Sound bridge improvement program, announced last year. Safe and Sound, aimed at fixing 800 of the weakest bridges, will cost between $400 and $600 million. It is a 25-year program. Eighty-three Southeast Missouri bridges are included in the Safe and Sound program.

In Illinois, Governor Rod R. Blagojevich is asking lawmakers to consider a $10 billion plan for improvements to the his state's infrastructure, including bridges.

Kevin Grammer, operations engineer for Illinois Department of Transportation, said, like Missouri and other state transportation offices, IDOT began extra inspections after the collapse in Minnesota. IDOT made its biannual inspections in March,

Among those checked: Cairo-57, a steel-arch bridge built in 1978, which carries four lanes of I-57 traffic from Charleston, Mo., to Cairo's northern tip. To the south, near Birds Point, Mo., is a bridge on which U.S. 60 and 62 converge over the Mississippi. The steel-truss bridge was built in 1929 and renovated in 1983 and 2005.

"Nothing causing us any concern for the structural integrity of the bridges were found," he said.

Interstate 57 Mississippi River bridge at Cairo, Ill.

A third steel span in Cairo, just 1,000 feet from the U.S. 60-62 bridge, carries U.S. 51, 60 and 62 from Cairo across the Ohio River into Wickliffe, Ky. Kentucky's department of transportation maintains that bridge. Saturday night, Kentucky officials closed the bridge nearly four hours after a barge hit a pier, according to the U.S. Coast Guard Louisville Operations Center. The barge Mabel L struck a pier of the bridge at 9:39 p.m. It was towing three empty barges at the time. An inspector found no visible signs of damage and the bridge reopened at 12:50 a.m.

The Cairo-Wickliffe bridge is currently being cleaned and painted at a cost of more than $250,000.

Power-washing and painting is part of a maintenance routine that includes checking and fixing joints and looking for signs of rust and stress, Grammer said.

Inspectors also look for scaling and mechanical damage. They rate bridges in broad categories, such as "structurally deficient" or "functionally obsolete."

Those terms can be misleading, Grammer said.

A bridge with an older railing leading from the road to a span could be deemed structurally deficient. A functionally obsolete bridge may have been built when trucks were smaller.

The terms are part of the National Bridge Inspection Standards, which includes a nine-point rating scale for the deck, the ground supports and the connection between above-ground supports.

"If we say it's a four, we all know what that means," Grammer said. "If a bridge wasn't safe, it would closed."

Depending on the one-two-nine scale, with nine being the highest rating, inspectors can set weight limits on bridge traffic.

Highway 60-62 Mississippi River bridge at Cairo, Ill. (Fred Lynch)

The Cairo bridges are considered fives, or satisfactory, and the Chester bridge's current ranking is four, or fair. Bill Emerson Memorial Bridge earned all nines in its last inspection.

Some inspections require more work.

"If we see erosion of metal, we'll do testing," he said.

One test uses penetrating dye to reveal microscopic cracks.

Grammer said that although he has ordered bridges closed over his career, no Illinois bridges have been shut down in his district since the Minnesota bridge collapse.

The Chester bridge, finished in 1942, closed for nearly two years after a severe storm in 1944 sent two of the bridge's spans into the water. The bridge reopened in 1946.

Southeast Missourian reporter Chris Harris contributed to this story.

pmcnichol@semissourian.com

335-6611, extension 127


See two bridges that connect Illinois with Kentucky and Missouri


Chester bridge, by the numbers

* 1942: Year it opened as a toll bridge.

* 1946: Year it reopened after a severe storm destroyed main span, on July 29, 1944.

* 669.8: Length, in feet, of main span

* 35,000: Amount of steel, in tons

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