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

By on January 18, 2018

From CBS:  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.

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.

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