EDWARDS, Colo. -- All commercial vehicles traveling on Interstate 70 in Colorado, between milepost 133 (Edwards exit) and milepost 259 (Morrison exit), must now carry sufficient chains to be in compliance with the states chain law.

The law requires commercial vehicles to carry chains on this segment of I-70 from September to May 31.

Colorado's chain law applies to all state and federal highways and interstates and includes two levels for commercial vehicles.

Chain Law Level 1 requires all single-drive-axle commercial vehicles to chain up. The drive wheels must be chained; cables are not permitted as an alternate traction device. All other commercial vehicles must have snow tires or chains.

Level 1 may be implemented any time there is snow covering any part of the traveled portion of pavement on an ascending grade.

Chain Law Level 2 requires all commercial vehicles to chain up. Buses must chain two drive wheels to comply. Level 2 may be implemented any time there is snow covering the entire traveled portion of pavement on an ascending grade or when driving conditions dictate this level is necessary to protect safety and minimize closures.

To help assure commercial vehicles have a safe location to chain up or down, the Colorado Department of Transportation has 21 chain stations along the I-70 west corridor. Yellow signs indicate chain station locations.

In addition, CDOT has a few chain stations on the I-70 east corridor at mileposts 289 and 343 eastbound and milepost 358 westbound. There is also a chain station located on northbound I-25 at milepost 157 (near Monument) and southbound at milepost 172 (near Larkspur).

The alternate traction-control device known as the AutoSock remains an approved device in Colorado. Vehicles carrying 16 passengers or more will have the option of using AutoSock rather than chains.

The AutoSock is a fabric that slips over a vehicle's outer driving wheels, providing extra traction on snowy and icy roads. It can be installed over tires in less time than traditional chains.

CDOT also offers what it calls the "chain assistance program," which allows vendors to assist commercial vehicles when the Colorado Chain Law is in effect by selling and installing chains and other approved equipment.

Vendors will be on site at chain stations where the chain law is in effect. The service will be available starting around Thanksgiving, depending on weather.

For more information, go to www.cotrip.org.