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Rain Could Further Delay Nearly-Complete I-35/U.S. 30 Interchange Opening

courtesy Iowa DOT
A DOT camera captured this image of the interchange of I-35 and U.S. 30.

A three-year-long construction project to improve safety at the U.S. 30 - Interstate 35 interchange in Ames is nearly complete.

The Iowa Department of Transportation is planning to open a new flyover ramp Thursday morning, weather permitting. District 1 construction engineer Jesse Tibodeau told IPR Tuesday afternoon that painting on the road surface is the only work the contractor has left to complete before the new traffic pattern can be opened. But that job requires dry pavement and has to happen at night because a lane of I-35 will be closed. If rain late in the day makes the pavement wet during the overnight window when the interstate can be closed, a further delay is possible.

The Thursday morning target opening is already a day later than DOT had previously announced. For nearly a week, messages on I-35 northbound said the new flyover would open today.

The redesign began in 2016 to replace a cloverleaf, which DOT says had become inadequate for the volume of traffic. About 10,000 of the vehicles that come north on I-35 each day exit onto U.S. 30.

The old interchange had traffic merging onto I-35 north using the same lane as the northbound I-35 traffic exiting for U.S. 30 west. But when the flyover is open, northbound I-35 traffic will take one exit for U.S. 30, from which the eastbound drivers will peel off and the westbound traffic will curve onto the new flyover and then merge onto U.S. 30 with the vehicles entering 30 west from I-35 south.

Confusing as it sounds written out on the page, the new traffic pattern will be safer. Ames Police Commander Geoff Huff says the old design made a lot of people nervous.

“There’s an on ramp and an off ramp within a pretty short period of time,” he says, “and so there’s always this kind of conflict between people getting onto [Interstate] 35 and people trying to get off of 35 almost in the same location.”

Huff says the flyover ramp design also means cars aren’t reducing speed and then quickly needing to get back up to highway speed.

“It allows you the time to get a little bit closer to highway speed once you start merging onto highway 30 as opposed to that cloverleaf, where you really gotta slow down to like 25 miles per hour. And that’s in good weather.”

Huff says he and other law enforcement colleagues often marveled that even more accidents didn’t happen on the old cloverleaf.

Traffic will be heavy in Ames on Saturday as Iowa State University hosts the University of Iowa in the annual in-state football rivalry. But Huff says fans arrive gradually over many hours so he doesn’t expect the new interchange will have much effect. The real traffic bottleneck, he says, comes after the game when everyone leaves at once and that flow won’t require the new ramp.

Huff says law enforcement will be paying attention to how the traffic moves, though, and if necessary they’ll reserve the right to make adjustments to flow, especially on big football game days.

Amy Mayer is a reporter based in Ames