Every winter, travelers headed from Denver International Airport to Breckenridge, Vail or Aspen ask some version of the same question: what happens if I-70 closes while I am on it? Our founder worked that highway as a Colorado State Trooper before starting Summit Black Car, so the answer below comes from the side of the closure gate that most travelers never see. It covers where the road closes and why, what the Colorado Traction Law requires of the vehicle you are riding in, and how our chauffeurs decide whether to wait or go around.
The traction law is the baseline. When conditions get worse, CDOT can escalate to the Passenger Vehicle Chain Law, which requires every vehicle, including those with AWD or 4WD, to carry chains or an approved alternative traction device. Our chauffeurs carry them and know when they are required. Neither law is a guarantee of passage; a closure is a closure, and the decision to hold or reroute is made with live CDOT information.
Where I-70 closes, and why
The mountain section of I-70 has four places that account for most of its closures.
Floyd Hill is the first long grade west of Denver and the first place the corridor narrows. A crash or a stuck truck there in a storm backs traffic up toward the metro area before anyone has reached the mountains, and it is the closure that catches travelers who assumed the trouble would start higher up.
The Eisenhower-Johnson Memorial Tunnel sits at 11,158 feet on the Continental Divide. It closes for storms, for crashes on the approaches, and for hazmat holds. Vehicles carrying hazardous materials are not allowed through the tunnel and normally use Loveland Pass instead; when the pass is closed by weather, those trucks are escorted through the tunnel in groups while everyone else waits. During heavy traffic and storms, CDOT also meters vehicles at the portals to keep the tunnel from filling with stopped cars. Metering is not a closure, but from the queue it can feel like one.
Vail Pass, at 10,662 feet, closes several times each winter. The usual causes are crashes on the grades, trucks that cannot make the climb, and storms that outrun the plows. When Vail Pass closes, traffic between Summit County and the Vail Valley stops in both directions.
Glenwood Canyon, between mile markers 116 and 133, is a different problem. Its closures come from rockfall and mudslides more than snow, which means they can happen in a summer thunderstorm as easily as in January. When the canyon closes, the road between the Vail Valley and Aspen is cut.
What the Colorado Traction Law requires
The Colorado Traction Law is in force every year from September 1 to May 31 on I-70 between Morrison, at mile marker 259, and Dotsero, at mile marker 133. It does not wait for a storm; it applies for the whole season.
To be on that stretch of road legally, a vehicle needs one of the following:
- All-wheel drive or four-wheel drive with at least 3/16 of an inch of tread on winter tires marked with the mountain-snowflake symbol, all-weather tires, or tires marked M+S.
- Chains or an approved alternative traction device.
Every SUV and Sprinter in our fleet meets the law every day of the season. Our passengers do not have to think about it, and they do not have to think about it when the Colorado State Patrol sets up a chain-law checkpoint on the approach to the tunnel or Vail Pass. If you are considering a rental car instead, look at the tires before you leave the lot; the law is about the equipment on the vehicle, not the vehicle’s drivetrain badge.
How a closure actually unfolds
From the trooper’s side, a closure is a sequence rather than a single event.
It usually starts with an incident: a crash, a jackknifed truck, a vehicle that lost traction and blocked a lane. Troopers and CDOT close the affected lanes, then the whole direction if the scene cannot be worked around. CDOT drops the closure gates at the last exit where traffic can be turned, and traffic is held there and at the exits behind it. On the westbound side that often means holds at Georgetown or Silverthorne for the tunnel and at Frisco or Copper Mountain for Vail Pass.
A weather closure works the same way without the crash. When visibility or road surface reaches the point where the plows cannot keep up with the traffic, the road is closed until they can.
Reopening is the part nobody can schedule. The scene has to be cleared, the road plowed and treated, and then the queue released in stages. A crash closure often clears in a couple of hours. A storm closure lasts as long as the storm. A hazmat hold at the tunnel is usually short. A chauffeur who knows which kind of closure is in front of the vehicle can give a passenger a useful estimate instead of a shrug.
The Hoosier Pass alternate
Breckenridge has an alternate that the other resort towns do not. When I-70 closes east of the tunnel, the way in is US-285 southwest from Denver to Fairplay, then Highway 9 north over Hoosier Pass at 11,542 feet and down into town. It is longer, it is a two-lane mountain road with weather of its own, and it is the right call more often than travelers expect.
The catch is that the decision has to be made early. US-285 leaves the Denver metro area near Morrison; once a vehicle is committed to I-70 past Floyd Hill, there is no practical way across to it. That is why our chauffeurs check the corridor before leaving DIA rather than after the queue forms.
Vail, Beaver Creek and points west have no equivalent. When Vail Pass closes there is no short alternate, and when Glenwood Canyon closes in winter the detours run hundreds of miles because Independence Pass, the summer route into Aspen over Highway 82, closes each year around the first week of November and does not reopen until the Thursday before Memorial Day. In those cases we hold and time the reopening rather than drive half the state.
How our chauffeurs decide to hold or reroute
The decision is made in a fixed order.
Before departure, the chauffeur checks the tunnel, Vail Pass and Glenwood Canyon, along with the forecast for the hours the trip will be on the road. If a closure is already in place, we adjust the departure time or, for Breckenridge, take US-285 from the start.
On the road, the chauffeur watches for the decision points. For a Breckenridge trip, the last one is where US-285 branches off. For everyone else, the question is where to hold if the road closes ahead: a town with fuel and food rather than a shoulder on the grade.
When a closure happens with the vehicle already in the corridor, the chauffeur tells the passenger what closed, why, and what that usually means for reopening, then moves to the hold point. Flight tracking runs on every airport pickup, so a delayed arrival adjusts the pickup without a call from the passenger. On the return, we plan the drive time plus 30 to 45 minutes of winter weather margin plus the airline’s check-in time, and we plan more on Sunday afternoons and holiday Mondays, which are the slowest eastbound periods on I-70 all year.
What you can do as a traveler
- Give us your flight number when you book so tracking is in place.
- Keep your phone on after landing; the chauffeur will confirm the meeting point and any change in timing.
- On a Sunday or holiday departure, accept an earlier pickup than the drive time alone would suggest.
- Tell us your passenger count, bags and ski gear so the right vehicle is assigned and loaded once.
- If the road closes, let the chauffeur make the call. Waiting an hour at a warm hold point beats a five-hour detour over roads in the same storm.
