Why Cincinnati's recent flooding has us thinking about the Brent Spence

Roadways, waterways

The recent flash flooding in Cincinnati got us thinking about the Brent Spence Bridge Corridor project.

The heavy rain this week did not appear to damage construction on the project, but it did remind us of an important connection between bigger roads and bigger floods.

This week's worst flooding happened in Hyde Park, Oakley, Madisonville, and Norwood, although other neighborhoods were also affected. Streets turned into rivers, basements filled with water, and many people were left cleaning up.

News reports say part of the problem was a floodgate on the Duck Creek, which runs through or next to these communities, that failed to close during the storm. At the same time, four to six inches of rain fell in about an hour, which proved more than the area's sewer system could handle. The Metropolitan Sewer District of Greater Cincinnati received more than 900 reports of sewer backups and basement flooding related to Friday's heavy rainfall, according to Cincinnati Public Radio.

All that water, nowhere to go

So what does this have to do with highways?

The answer is something called impervious surfaces. These are hard surfaces like roads, parking lots, and buildings where rain cannot soak into grass or soil.

The U.S. Geological Survey says that as cities grow, more land is covered by pavement and buildings. When that happens, more rainwater runs across the ground instead of soaking into it. Research from the Environmental Protection Agency and others also says this extra runoff can carry pollution into streams and rivers.

The neighborhoods that flooded this week have seen a lot of new development over the past 20 years. Around Duck Creek alone, several major projects have added new pavement:

• The Duck Creek Connector opened in 2017.

• The Red Bank Expressway was widened.

• Madison Road was widened through Madisonville.

• Oakley Station replaced the old Millworks site with a large shopping center.

• ODOT widened I-71 between the Norwood Lateral and Ronald Reagan Cross County Highway in 2021.

These projects are only part of the picture. New homes, businesses, parking lots, and access roads have also increased these neighborhoods' impervious surface area, meaning fewer places for rainwater to soak into the ground.

This is (just one of many reasons) why the Brent Spence Bridge Corridor project raises concerns. The project will widen the interstate from eight lanes to 16 lanes and use 51 acres of land. Not all of that land will become pavement, but much of it will.

As storms become more intense, we need to think carefully about how we build our roads. Adding more pavement can mean more water rushing into neighborhood streets, streams, and storm drains, while things like increased public transit and other car-alternatives can reduce traffic congestion without posing those risks.

If transportation planners continue to rely mainly on widening roads to solve traffic problems, we worry that flash floods like the ones we saw this week could become more common in communities across Greater Cincinnati.