Converting 3rd and 4th streets to two-way thoroughfares would include traffic roundabouts at 10 intersections that would cost less to change than using traffic lights, Davenport aldermen learned Monday.

The idea of roundabouts was met with groans from some on the city council, while other aldermen defended it.

“This isn’t something being used just in big, progressive cities,” Alderman Jason Gordon, at-large, said during the council work session. “They are being used in small Midwestern cities.”

Several aldermen traveled to Carmel, Ind., just north of Indianapolis, recently to see what that city has done with roundabouts.

A roundabout is a circular intersection with a raised dome in the center that requires vehicles to yield to other vehicles and slow down as they go through the intersection or go around it to exit the roundabout. The outside of the dome would be about 2 inches high with a concrete dome about 6 inches high in the center. Some cities place landscaping in the middle.

The two-way change would run from Telegraph Road through downtown to River Drive.

Public Works director Mike Clarke described “mini-roundabouts” for the intersections of 3rd and 4th streets with Iowa, Harrison, Gaines, Marquette and Division streets. State approval would be required for the Harrison Street intersections because Harrison is a state route carrying U.S. 61 traffic.

The original estimate to convert the one-ways to two-ways was $2.2 million to install new traffic lights along the route. But the plan presented Monday to use a combination of roundabouts, stop signs and traffic lights would cost only $500,000.

Aldermen also heard about a plan to implement parallel parking on Harrison Street from 6th to 16th streets. The plan received positive comments from area business owners and representatives of the Hilltop Campus Village. Most of the work to convert the parking could be done by Public Works crews with no significant costs.

Both the Harrison Street and 3rd and 4th streets projects will be included in the capital improvement plan presented at the city council budget session at 9 a.m. Saturday at City Hall. Alderman appeared likely to act on the Harrison Street project, but move more slowly on the conversion of 3rd and 4th streets.

Fire Chief Lynn Washburn raised a safety concern with the roundabouts and how they could impede a fire truck and slow response time. Three companies that operate out of the Central Fire Station would be affected.

“We would talk to other departments about how they deal with it,” she said. “A 100-foot aerial won’t make a nice easy turn like a car.”

Kyle Carter of the Downtown Davenport Partnership spoke in favor of the plan, saying two-way streets would make the downtown more accessible and open up more parking as the downtown continues to grow.

“We see this as something that can continue to catapult us in that direction,” he said.

The change on Harrison Street would likely occur in the summer after a significant educational and informational push, Clarke said. The parking spots would be 25 feet long so that most vehicles could pull into the spot without having to back up.

On Harrison Street, the traffic count at Locust Street is 15,000, but it drops off toward the downtown. The parking plan would include three lanes of traffic during peak commuter times in the morning, Clarke said.

DeAnn Soults of Crescent Cleaners was in favor of the change.

“Businesses don’t have parking,” she said. “They really need that parking on Harrison Street.”

Wendi Laake, who just opened a retail store, Eclectic, in November, agreed, saying she would love to have parking on the east side of Harrison, near her location.

Tim Phillips of St. Ambrose University said the university favors the change to improve walkability in the area and pedestrian safety so that students would have fewer vehicles on campus.