Rule number one before you go: When driving in Ski Country, check the weather (weather.com or your favorite) and go to the Colorado Department of Transportation website Cotrip.org and check the speeds and road conditions. Google maps drive time and Waze are essential cellphone apps for keeping apprised of road conditions and drive times which can change quickly. Your co-pilot/navigator should have these apps and be proficient using them since the driver will have his hands full. Obviously drive slower during snowstorms and drive commensurate with road conditions and visibility.
Day skier traffic can be unbearable in Colorado on Saturday and Sunday mornings and afternoons. Driving the I-70 corridor in ski season is guaranteed to be slow on Saturdays and Sunday mornings from 0600 am to 1000 am; and Saturday and Sunday after skiing. If it is snowing, it will take a long, long time. If you can, avoid these times. Lots of day skiers are on the lift at 0830 and off again at 1230 pm on weekends to avoid the traffic. On Sundays, the traffic can get heavy at 1100 am back to Denver. Just so you know.
The frontage road from Georgetown to Idaho Springs is a safety valve but eventually will fill up also. Watch your speed on the frontage road (mostly 30 mph) because the Colorado State Patrol is out there. The eastbound Express Lane (Toll lane) from Georgetown to Idaho Springs helps a little.
Colorado has a stringent Traction Laws for trucks and passenger vehicles requiring snow tires in adequate condition. Tires must have mud/snow (M+S) designation, or a four-wheel/all-wheel drive vehicle and tires must have a minimum one-eighth inch tread. During severe winter storms, CDOT will implement the Passenger Vehicle Chain Law which is the final safety measure before the highway is closed. Under a Passenger Vehicle Chain Law, every vehicle on the roadway is required to have chains or an alternative traction device. Motorists driving with inadequate equipment during a Traction Law or Passenger Vehicle Chain Law could be fined more than $130. If a motorist blocks the roadway because they have inadequate equipment during a Traction Law or Passenger Vehicle Chain Law, they could be fined more than $650.
CDOT will close the highway due to severe weather and accidents to clear the highway, but will not leave you stranded on the road. The closure is generally made at an exit where you can get off. In any case, you may want warm clothes to survive the wait which may be hours.
When it’s snowing, snowplows create a moving block down the highway slowing and blocking traffic. Don’t attempt to pass snowplows unless they let you by. Driving conditions are far better behind the plows which lay down sand, gravel, and salt during snowstorms. But don’t follow too closely… if too close behind the plows, the gravel spray can crack your windshield. The magnesium chloride road salt helps keep roads clear but can seriously block your windshield and vision with goo. Make sure your washer fluid is full before going up. If you can no longer see out the windshield, pull over on an exit or rest stop and use snow to clear your window (and headlights). A window squeegee is handy in this case or napkins at the very least.
The highway is banked on curves in accordance with federal highway specifications. Unfortunately if it’s icy, the rear of your car is going to slide out to the side of the road. Rear wheel drive vehicles will have the most trouble if forced to stop. Idaho Springs and the Eisenhower tunnel approach are notorious locations for rear wheels slipping towards the shoulder. Keep rolling if you can.
Don’t be over-confident in your 4WD SUV. Most vehicles that end up in the ditch are SUVs… presumably with inexperienced drivers driving too fast. If you are not an experienced mountain driver, slow down with your SUV and drive with traffic.
Be very careful on bridges which freeze before the road surface. The expansion joints on the edge bridges can cause a wheel hop and start you spinning. In any case, don’t exceed the speed limit because the CSP is on the highway. This especially true on long downhills where your speed can run away.
Make sure you have plenty of gas before you leave since traffic could come to a dead stop and you want to run the engine. Don’t chance an empty tank. Carry warm clothes with you in the case of a long wait.