Select Page

Winter Driving

« Back to the December 2018 edition

El Nino weather patterns are hard to predict, other than they make for a warmer and wetter winter.

Still, ODOT crews are prepared for the season. The hope is you will be prepared for winter driving as well.

“Winter weather seems to vary from one season to the next,” said ODOT District Manager Jerry Marmon. “Last winter was different than this winter – so far- but the partnerships we have with California and the driving public are the same.”

That means being prepared on the I-5 drive from the Rogue Valley all the way to Redding.

“Every winter, we meet drivers stuck in the snow, trying to chain up but dressed like they’re on a beach vacation,” said Everett Carroll, Ashland Maintenance manager. “The Siskiyou Pass is no place for shorts and flip-flops. You need to come prepared.”

Snowstorms don’t know political boundaries. That is why the section of I-5 from the California border to Exit 11 south of Ashland with Siskiyou Summit in the middle is challenging. Weather conditions change rapidly. Carroll said it’s not uncommon for a snowstorm to close the interstate on the California side of the mountain pass while road conditions remain dry and clear near Ashland.

“You never know what to expect, so you have to expect everything,” said Carroll.

Prepare for the worst

“Every winter has different impacts on the I-5 corridor,” said Marmon. For instance, last year saw nine chain requirements and no full closures over Siskiyou Summit while north of Grants Pass it was a different story. There were two long-term closures and 11 chain restrictions on Sexton, Smith and Stage passes, which stretch 15 miles. Each is about two-thousand feet lower in elevation than Siskiyou Summit and each pass and valley can have different weather characteristics or micro-climates.

“Lower elevation snow is much more difficult to forecast because it occurs irregularly and we don’t always know how much cold air is trapped at lower elevations preceding a storm – or if and when cold air will mix out and warm up,” said National Weather Service Warning Coordination Meteorologist Ryan Sandler.

Sandler said Siskiyou Summit is higher and more exposed, which makes forecasting snow easier, but not easy.

“Poor visibility can be a big driving issue for both areas but under different weather patterns. Siskiyou Summit might poke up into the clouds, causing visibility to be reduced to near zero in dense fog,” he said. “Across the passes north of Grants Pass, there could be high pressure with fog in the valleys.

Maintenance practices

ODOT’s ability to use salt when needed receives a lot of media and public interest. However, salt is not the only tool in the agency’s winter maintenance toolbox. Salt complements a variety of resources ODOT maintenance crews use to combat the effects of winter on the I-5 corridor. For example, crews apply deicer (magnesium chloride) and sanding material (cinder) on hills, curves, bridges and known trouble spots. The deicer is used as an anti-icer before the storm to help prevent ice from forming on the road, and as a deicer after the storm to help break the bond between ice and the road.

“We can’t stop the snow but we can prevent it from bonding to our highways,” said Marmon. “We are constantly improving efficiencies and equipment that allow our maintenance crews to focus on more areas during winter storms.”

Winter maintenance practices include plowing, sanding and applying winter anti-icing liquid and finally, salt. Crews use snowplows to clear snow, and they use frame-mounted tailgate sanders, deicer trucks and spreaders to sand and salt roadways. On the Siskiyou Pass, pusher trucks (trucks equipped with counterweights over the rear axle for better traction and thick rubber noses over the front bumper) are called in to push and straighten out stalled or jackknifed commercial trucks that can close down all lanes in a moment.

“This is all about partnerships and the driving public is at the center,” said Marmon. “We have crews and equipment ready. Drivers need to be prepared as well – and a big part of that is driving to conditions, maybe even waiting until conditions improve, and keeping informed through”

Pay attention to these four snow zone messages:

Carry Chains or Traction Tires
The chains or traction tires must be in or on your vehicle, and they must be the right size for your vehicle and of sufficient number to comply with the chain rules.

Chains Required on Vehicles Towing or Single Drive Axle Over 10,000 GVW
You must use chains if your vehicle is rated 10,000 pounds GVW (gross vehicle weight) or less and is towing; or is a single drive axle vehicle rated over 10,000 GVW. Chains must also be used on the trailer or vehicle being towed to comply with chain rules.

Chains Required on Vehicles Towing or Over 10,000 GVW
Vehicles towing or rated for more than 10,000 pounds GVW must use chains.

Chains Required-Traction Tires Allowed on Vehicles Under 10,000 GVW
Vehicles towing or rated for 10,000 pounds GVW must use chains. Vehicles weighing 10,000 pounds GVW or less and that are not towing must use chains or traction tires.


Extreme winter conditions on Interstate 5 Siskiyou Pass and the summits north of Grants Pass often require a conditional road closure – a requirement for all vehicles to use chains regardless of the type of vehicle or type of tire. ODOT and Oregon State Police maintain check points and will turn a motorist around if they aren’t prepared.

I-5 Southern Oregon Chain Restrictions

1. Carry Chains
Chains must be in or on your vehicle and must be the right size and of sufficient number to comply with chain laws.

2. Single Axle Trucks and Vehicles Pulling Trailers
All single axle trucks over 10,000 GVW (gross vehicle weight), trucks pulling double trailers, and any vehicle pulling a trailer is required to install chains. Traction tires cannot be substituted for chains.

3. All Trucks and Vehicles Pulling Trailers
All trucks over 10,000 GVW as well as any vehicle pulling a trailer needs to chain up. Traction tires cannot be substituted for chains.

4. Full Chain Restriction
This is Oregon’s most severe winter restriction. All vehicles, with the exception of vehicles with 4-wheel drive (unless towing) and emergency response vehicles, are required to install chains. A traction tire is not allowed to substitute for chains.

Check out this primer on how to drive I-5 Siskiyou Summit in the winter:



« Back to the December 2018 edition