During a winter storm, a mountain interstate corridor is placed under an active traction law for passenger vehicles. What does compliance generally require of a standard two-wheel-drive car?

Why B is correct

Colorado's mountain corridors operate a graduated code system in winter, and when a traction law activates, passenger vehicles must demonstrate actual grip: adequate tread depth snow tyres, chains or an approved alternative, or an all-wheel/four-wheel drive vehicle on appropriate tyres. The point of the code is empirical — braking and climbing on packed snow is tyre-dependent, and a car on summer rubber becomes a projectile the moment the grade steepens. Drivers who proceed without the required equipment face fines, and worse, become the obstacle that closes the corridor for everyone behind them.

Why the other options are wrong

A. Nothing; traction laws apply only to commercial trucks

Commercial vehicles face their own, stricter chain codes, but the passenger-car traction law exists precisely because ordinary cars slide off mountain grades every winter. Excluding them would leave the corridor's most numerous users unregulated.

C. Driving at any speed with hazard lights activated

Hazard lights communicate a stopped or disabled vehicle, not legal grip. Speed and flashers change nothing about what the tyres can and cannot do on packed snow.

D. Waiting until the law is lifted, because no passenger car may proceed at all

Traction codes restrict equipment, not all travel. A two-wheel-drive car with proper snow tyres or chains satisfies the code and proceeds — the law demands traction, which is purchasable, not absence.

On the road

A February powder closes in on the foothill corridor and the variable sign flips to the traction code. You watched the retrofit guy mount winter tyres in October, so your wagon climbs the grade at the flow with snow still falling. Two cars in the median beyond the curve — both on all-seasons, both fine in July — are the code's entire argument, restated in sheet metal.

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