Conditional Closures on the Siskiyou Pass

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Extreme winter conditions on the Interstate 5 Siskiyou Pass often necessitates a conditional road closure – a requirement for all vehicles to use chains regardless of the type of vehicle or type of tire. While a conditional road closure may be placed on any of Oregon’s state highways, the requirement is most frequent on the Siskiyou Pass because of the highway geometry, driver experience and relatively high volumes of traffic.

“Every winter we encounter motorists who have never heard of a conditional closure requirements on Siskiyou Pass,” said Everett Carroll, ODOT’s Ashland maintenance manager. “This is perhaps the least understood restriction for the Siskiyous.”

ODOT and Oregon State Police maintain check points on either side of the Siskiyou pass and will turn a motorist around if they aren’t prepared. The basic Carry Chains requirement and three additional types of conditional closures are used on the Siskiyou Pass:

Carry Chains

When signs say you must carry chains, the chains must be in or on your vehicle, and must be the right size and of sufficient number to comply with chain laws.

Single Axle Trucks and Vehicles Pulling Trailers

Under this conditional closure, 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.

All Trucks and Vehicles Pulling Trailers

Under this conditional closure, 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.

Full Chain Restriction

This is the most severe winter conditional closure used in Oregon (short of a full closure). Under the Full Chain restriction, all vehicles with the exception of 4-wheel drive and emergency response vehicles, are required to install chains. A traction tire is not allowed to substitute for chains.

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