The Colorado State Patrol has issued its first citations of the winter driving season, ticketing two commercial vehicles for failing to carry chains.

State Trooper Gabriel Moltrer said in an email that troopers issued the citations for violations of the state’s must-carry commercial vehicle chain law during two separate traffic stops on Interstate 70 near Avon and Vail on Sept. 7.

Colorado’s “must-carry” law requires commercial vehicles over 16,000 pounds to carry chains at all times on mountain roadways such as I-70 between Sept. 1 and May 31.

The state’s mountain roadways are not only steep and winding, but can experience extreme winter weather nine months of the year. For commercial motor vehicles, which make up about 10% of traffic on I-70, these roads can be challenging any time of year, but winter can be especially dangerous, according to the State Patrol.

In 2024, the state legislature updated the must-carry chain law to expand which roads it applied to, including parts of Colorado Highway 9 from Frisco to Fairplay, U.S. Route 50 near Salida and others. On I-70, commercial vehicles are required to carry chains at all times when driving west of Morrison during the winter months.

Moltrer said that state troopers conduct checks to ensure that commercial vehicles are carrying chains anytime they stop a vehicle on mountain roads. Port of entry officers also conduct proactive chain checks about twice a month at weigh stations where commercial vehicles are required to pull off, he said.

During the first winter of the updated law, Moltrer said troopers issued 641 citations to commercial motor vehicle drivers for chain law violations and port of entry officers issued 902 citations.

Despite last winter being mild with a record-low snowpack, the number of citations issued nearly doubled as state patrol ramped up enforcement. Moltrer said troopers issued 586 citations for chain law citations and port of entry officers issued 2,405 chain law citations.

Commercial vehicles that fail to comply with the winter driving restrictions face a fine up to $500 plus a $79 surcharge, or up to $1,000 plus a $157 surcharge, if the vehicle is stuck and blocking a traveled portion of the roadway, according to the State Patrol.

Vail has also instituted its own local chain law regulations with steeper penalties for violations. Under the local law, a $1,500 fine may be issued to drivers operating without chains when conditions warrant and commercial vehicles that block Vail Pass due to a failure to use chains are subject to a $2,650 fine, more than double the state’s penalty, according to the town’s website.

The Colorado Department of Transportation estimates that the state’s economy loses about $2 million for every hour that I-70 is closed due to a crash.

Colorado also has a passenger vehicle traction law in effect from Sept. 1 to May 31. Under that law, CDOT can restrict travel to vehicles that don’t meet minimum requirements when conditions are snowy and icy. During these times, CDOT will announce that passenger vehicle law is active using variable message boards on I-70 and the state’s interactive map available at COTrip.org.

The law requires all passenger vehicles to have tires with a tread depth of at least 3/16-inch and rated as “all weather” or “mud and snow” tires. Drivers can look for markings stating “All season,” “M+S” “M/S” or an icon of a mountain with a snowflake to determine whether their tires meet the requirements, according to state officials.

If passenger vehicles do not have the proper tread depth and tire type, the law requires drivers to have chains or an approved alternative traction device on two or more tires when the law is activated.

There is a $50 fine plus a $17 surcharge for violating the passenger vehicle traction law, according to State Patrol.