Brett Blume (@brettblumekmox)

ST. LOUIS (KMOX) – Congestion and safety are two of the biggest factors driving talk about replacing the Chain of Rocks Bridge that carries Interstate 270 over the Mississippi River, a bridge which opened in 1966.

“(This project) will give us a bridge that will have a 50 year or longer service life,” Cindy Stafford, location studies engineer with the Illinois Department of Transportation (IDOT) explained during an open house Wednesday in Granite City. “We won’t have to do extensive and lengthy repairs. It will help us plan for current traffic volumes and future traffic volumes, which as you know there’s a lot of congestion out there.”

IDOT provided numbers showing that as of 2015 the bridge carried an estimated 51,000 vehicles per day, with that volume expected to increase to just under 70,000 by the year 2045.

newbridge2 New I 270 Bridge Would Be 6 Lanes Wide, Have 10 Foot Shoulders

(KMOX/Brett Blume)

Back in 1975 the bridge carried fewer than 20,000 vehicles per day.

Nearly one in every five vehicles that currently crosses the bridge is a semi tractor trailer, adding to the wear and tear on the aging structure.

According to Stafford, the current narrow one-foot shoulders do not provide room for disabled vehicles without blocking a lane or maneuvering to avoid crashes.

She says the results of having narrow shoulders and high traffic volumes can be seen in the crashes experienced along the corridor.

newbridge3 New I 270 Bridge Would Be 6 Lanes Wide, Have 10 Foot Shoulders

(KMOX/Brett Blume)

In the most recent 5-year period, over 180 crashes occurred on the I-270 bridge.

That means IDOT has deemed the bridge as a “5% selected segment”, meaning it ranks in the top 5% of severe safety needs compared to similar roadways in Illinois.

Stafford says construction is still at least two years away, likely longer.

“We’re going to build the south structure first, move all of the traffic to the south structure, and then tear down the old bridge and build the north structure,” she explained.

One hang-up is funding — there’s currently none in place to cover the estimated $225 million price tag.

But Stafford said they’re up for several programs that would provide at least some of the needed funding, and they do have the money for the current first phase which involves preliminary engineering and environmental studies.

IDOT would work with the Missouri Department of Transportation (MoDOT) to secure funding for the new bridge, which would take at least two construction seasons to complete.


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