Drivers spent hours stuck on Interstate 5 as winter weather snarled traffic on Sunday and Monday south of Eugene.

State highway officials required chains on sections of the highway but vehicles lacking the equipment spun out or crashed on ice and blocked the freeway beginning at about 6 p.m. Sunday.

The gridlock continued well into Monday, with hours-long delays reported for northbound traffic, according to the Oregon Department of Transportation.

ODOT spokesperson David House said that despite crews preparing for the storm, laying down more de-icer and sand than in previous years, the severity of the storm hampered driving conditions.

He said an increased number of commercial vehicles, such as semi trucks, were not using chains this year. When those vehicles spin out, he said, they are more likely to block traffic.

It got so bad on I-5, House said, that drivers were simply stopping in traffic lanes to chain up instead of pulling off to the side of the highway. That backed traffic up so much that some drivers just sat in their cars and went to sleep.

“We and Oregon State Police had to go and wake people up to get them moving again,” House said.

Since then, House said, the weather hasn’t gotten better, and traffic has only compounded. Oregon State Police have begun handing out citations for drivers who aren’t using chains in required areas.

Clare Lewis was coming back from a weekend in California, expecting to reach Portland around 2 p.m. Monday.

She had a time constraint: Lewis was trying to get to Portland for an appointment for her cancer treatment on Tuesday morning. Instead, she got stalled around Cottage Grove.

She turned the car on and off intermittently, trying to save gas but keep warm. But as night fell, she was running out of water and was worried about running out of gas.

She had heard from a friend in Portland that there was an overnight buildup of traffic on I-5, but she didn’t think when she left Monday morning that it would still be so bad.

“You just feel so hopeless,” she said in a telephone interview from her car around 6:30 p.m. “There’s no indication of what’s going on.”

After about five hours, Lewis managed to get to the Cottage Grove exit and began making her way north on Oregon 99.

House, the ODOT spokesperson, urged people to stay off the roads Tuesday, when a final round of icy conditions is expected to hit.

“There are no alternate routes,” he said. “In normal weather, there can be a crash on I-5 and it still takes hours for backed up traffic to catch up. In this kind of weather where you can barely move, if you stop, you’ll get stuck. If you’re not chained up, you’ll definitely get stuck.”

—Jayati Ramakrishnan; jramakrishnan@oregonian.com