Conditional Closures on Siskiyou Pass

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In very bad winter road conditions all vehicles may be required to use chains regardless of the type of vehicle or type of tire being used. This is known as a conditional road closure. While a conditional road closure may occur on any of Oregon’s highways, they are most frequent on Interstate 5 through the Siskiyou Pass because of the geometry of the highway, experience of drivers, high truck traffic and overall large traffic volumes.

On the Siskiyou Pass, the basic ‘Carry Chains’ requirement and three types of conditional closures are used.

  1. Carry ChainsWhen signs say you must carry chains, the chains 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.
  2. Single Axle Trucks and Vehicles Pulling TrailersUnder this conditional closure, all single drive axle trucks over 10,000 GVW and any vehicle pulling a trailer is required to install chains. Traction tires cannot be substituted for chains.
  3. All Trucks and Vehicles Pulling TrailersThis next level of conditional closure requires all trucks over 10,000 GVW as well as any vehicle pulling a trailer to chain up. Traction tires cannot be substituted for chains.
  4. Full Chain RestrictionShort of a full closure, this is the most severe winter conditional closure used in Oregon. Under the full chain restriction, all vehicles with the exception of 4-wheel drive and emergency response, are required to install chains. A traction tire is not allowed to substitute for chains.

‘We often find motorists are unaware of the conditional closure requirements on Siskiyou Pass,’ said John Vial, district manager for the Oregon Department of Transportation. ‘When we say a full chain-up, we expect to have all non-exempt vehicles to be running with chains, not traction tires.

‘This is probably the least understood restriction for the Siskiyous.’According to Vial, 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.

« Back to the November 2007 edition