Driving I-70 in Winter: The Mountain Corridor

I-70 west of Denver is the road to almost every Colorado ski resort. It leaves the city at 5,280 feet, tops out at the Eisenhower Tunnel at 11,158 feet, and crosses Vail Pass at 10,662 feet on the way to Vail. On busy winter days, drive times on this corridor run close to double the clear-road figures.

The corridor, in order

Denver, then the foothills, then Idaho Springs. Empire Junction comes next, and after it the long grade toward the Divide.

The Eisenhower Tunnel carries the interstate under the Continental Divide at 11,158 feet — no vehicular tunnel in the country is higher. Past the west portal the road drops toward Silverthorne, 91 miles from the airport, and Frisco at 95.

Then it climbs again. Vail Pass at 10,662 feet is the second summit, and it arrives when the trip already feels mostly finished.

The tunnel decides the day

Everything bound for Summit County goes through the same bore. That makes it the corridor’s chokepoint in both directions, and it is why identical trips take wildly different amounts of time.

There is an alternative. Loveland Pass tops out at 11,990 feet, 832 feet above the tunnel, and hazmat loads must use it because they cannot go through the bore. It crosses the Divide instead of tunneling under it, on an exposed road that closes in the same weather that closes everything else.

The Mountain Express Lane

On peak ski weekends and holidays, Colorado opens a tolled express lane for 13 miles between Empire Junction and Idaho Springs.

It is reversible. The state runs it in whichever direction the day’s traffic demands, so you may see it on the way up and not on the way back.

Pricing moves with demand:

Toll level	Price
Base rate	$3
Ordinary heavy traffic	$8 to $15
Peak ceiling	$30

Whether it is worth $15 depends on the day, and no map will tell you. Some Saturdays those 13 miles save real time. Other Saturdays the lane and the general lanes move at the same speed for the same $15.

What a peak day costs in minutes

These are the routes where we hold a verified busy-day figure next to the clear-road one:

Destination	Clear roads	Peak day
Loveland Ski Area	1h 29m	2h 30m
Winter Park	1h 30m	2h
Keystone	1h 48m	2h 30m
Copper Mountain	1h 51m	3h 42m
Vail	2h 10m – 2h 45m	5h

Copper is the clean example. The busy-day drive is exactly double the quiet-day drive, and the extra 111 minutes buy no additional distance at all.

Routes without a confirmed peak figure are absent from that table. We do not fill gaps by extrapolating.

When the road closes

Closures are the other half of winter here, and they come from the state rather than from any driver’s plan.

Independence Pass, at 12,095 feet, closes for the entire winter. That is why the winter drive to Aspen runs about 40 miles longer than the summer one and goes through Glenwood Springs.

When I-70 closes: the detours

Each closure point has its own answer. Some have a real alternate route. Some have none, and waiting is the fastest option.

Eisenhower Tunnel: Loveland Pass, if it is open

When the tunnel stops, US-6 over Loveland Pass is the only other way across the Divide. The pass is open year-round, but CDOT closes it in winter for avalanche control, wind and drifting snow.

If the tunnel and the pass close together, there is no practical alternative. Traffic holds until one reopens.

Vail Pass: wait it out

There is no practical detour around Vail Pass. A guidebook estimate, not an official CDOT detour, describes the shortest loop. Take exit 171 onto US-24, go south over Tennessee Pass (10,424 feet) to Leadville, then north on CO-91 over Fremont Pass to I-70 at Copper Mountain.

That estimate puts the loop at about 53 miles and more than 2 hours, often inside the same storm. Waiting is usually faster.

Glenwood Canyon: the official northern route

This is the canyon on the winter road to Aspen. CDOT publishes an official alternate route: “Exit I-70 at Exit 205 (Silverthorne) and travel north on Colorado Highway 9 towards Kremmling. Travelers will continue west on US Highway 40 and then south on CO 13 to complete the alternate route and return to westbound I-70 at Rifle (Exit 90).”

CDOT recommends this northern route over southern options when a closure is expected to last more than 2 hours. CDOT gives no official distance for it, so we don’t quote one.

Floyd Hill: Clear Creek Canyon

During closures at Floyd Hill, east of Idaho Springs, CDOT sends traffic to US-6 at exit 244 through Clear Creek Canyon. The canyon’s tunnels have a 12’7” height limit, so tall vans need to know their clearance first. For that 2025 closure, CDOT also listed a local County Road 314 detour to exit 241 that adds under 10 minutes.

Berthoud Pass: the long way to Winter Park

Berthoud Pass, at 11,307 feet, closes for avalanche control. The detour runs through the Eisenhower Tunnel, north on CO-9 from Silverthorne to Kremmling, then east on US-40. It is far longer than the pass. There is no official mileage, so we don’t give one.

Where to check

CDOT posts closures on COtrip.org and in the COtrip Planner app. In Colorado, you can also dial 511. The Passenger Vehicle Chain Law is the last step before a closure.

Traction law, in one paragraph

From September 1 through May 31, Colorado’s traction law governs I-70 between Dotsero and Morrison. It is about tires rather than drivetrain, and all-wheel drive by itself does not satisfy it. The fines, the tread requirement and the reason rental cars fail it are covered in full here: Colorado traction law, explained.

How long the season runs

Colorado ski season typically runs from mid-November into April or May. Arapahoe Basin usually stays open into June.

The traction law window is longer than the ski season at both ends. It opens September 1, before the aspens turn, and holds through May 31.

Practical takeaways

• Plan against the peak figure, not the clear-road figure, on any weekend of the season.
• The tunnel approach is the bottleneck in both directions, so the drive back to DEN has the same shape.
• A closure is not a delay you can drive around. Vail Pass proves that several times a season.
• Tire compliance gets decided in the rental lot, not on the grade.

Related

• Denver to Vail car service — the full corridor, both passes
• Ski resort transportation — every resort on and off I-70
• Colorado traction law, explained — tires, fines and the September 1 start