New design planned for Avalon Road interchange

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Jim Leute
Friday, October 18, 2013

BELOIT—State Department of Transportation officials said Thursday that the Interstate 90/39 intersection with Highway 11/Avalon Road south of Janesville would be a diverging diamond interchange.

Part of the planned 45-mile Interstate reconstruction and expansion project, the interchange would be the second of its kind in Wisconsin, with the other being the Interstate's intersection with Highway 26/Milton Avenue in Janesville.

State officials outlined plans Thursday for the project's southern segment, a 12-mile stretch that runs from the Illinois state line to County O south of Janesville.

Steve Marshall, the segment's project manager, said designers considered a diamond interchange with signals, a diamond interchange with roundabouts and the diverging diamond design.

They settled on the diverging diamond interchange, sometimes called a double crossover diamond. It is designed to increase capacity and safety, decrease congestion and minimize the cost of new infrastructure.

Mike Preboske, a consultant on the segment, said 85 percent of the traffic to the Avalon Road interchange is destined for the Interstate. That results in a large number of left turns and creates problems for trucks on Highway 11, a state-designated truck route.

The diverging diamond, he said, would be a safer, more efficient design.

One man at Thursday public information meeting asked why the design was selected for Avalon Road, but roundabouts are being installed three miles to north at Racine Street.

Marshall said much of the traffic at the Racine Street interchange is thru-traffic, which is better suited for roundabouts.

Marshall said construction on the south segment will run from 2015 to 2020—assuming state funding scenarios hold up—and will cost approximately $250 million.

The state will reconstruct overpasses at Stateline, Creek and Woodman Roads, as well as interchanges at Avalon Road and County S.

Some people at Thursday's meeting were unhappy with the plan for Shopiere Road, which will include long stretches of concrete medians to the east and west that will block access to some local businesses and driveways.

“It's been working fine for 30 years, why rip the neighborhood to hell and make people drive a half-mile in each direction to turn around?” one man asked.

Marshall said the intersection is being redesigned with future development in mind, and the department tries to keep local access at least 1,300 feet away from the Interstate.

“It's tough to balance the safety of the traveling public with the prospect of land acquisition,” he said.

The state also plans to reconstruct a 2-mile stretch of Hart Road so it can be used as an alternate route during construction and traffic congestion on the Interstate.

One part of the project not discussed Thursday was the reconstruction of the I-90/39 with I-43 in Beloit. Marshall said that would be a topic for a future meeting.

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