New I-70 Left Lane Law: What Western Colorado Drivers Should Know

Winter driving in Colorado means snow, steep grades, and several slowdowns on I-70 across the state. Colorado’s updated left-lane restrictions plus traction & chain requirements could change how you drive through Glenwood Canyon, over Vail Pass, and toward Denver this season.

Keep scrolling to learn what has changed before your next run to Colorado’s ski resorts, or your next trip to Denver, via the mountain corridor.

What the I-70 Left Lane Law Is & What Changed in 2025–26

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According to the Sun, Colorado’s new left-lane law along I-70 prohibits commercial motor vehicles (CMVs) like semis and big rigs from lingering in the left (passing) lane, except when actively passing slower traffic. This change is to improve traffic flow and reduce slowdowns by keeping heavy trucks in the right lane where possible. CDOT says the update will help snowplows move more quickly and reduce the number of trucks blocking passing lanes during winter storms.

Where the Rule Applies & Who It Affects

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This left-lane restriction will apply to steep or weather-prone sections of Interstate 70, including Glenwood Springs, Down Junction (near Minturn), Vail Pass, Eisenhower-Johnson Tunnels, Georgetown Hill, and Floyd Hill. In these areas, CMVs must stay out of the left lane except to pass slower vehicles. Passenger cars in Colorado will continue to follow the general keep-right/pass-only rules.

Penalties & Enforcement + Traction/Chain Law Tie-Ins

Drivers should expect to see the Colorado State Patrol & CDOT actively watching I-70, and ticketing violators of the left-lane restrictions this winter. CMV drivers who violate these restrictions can expect fines and demerit points. Drivers should expect enforcement, especially during winter storms and peak holiday driving periods.

Motorists should also expect Colorado’s updated Traction and Chain Laws to apply to all drivers on I-70 between Dotsero and Morrison from September through May. You will need to travel with the proper winter traction equipment and meet tire/chain standards any time I-70 signs indicate the law is in effect.

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