In some cases, you have to leave a road to avoid a hazard or emergency. When you do, remember that:

A It is less dangerous to drive onto the shoulders than to cause a collision.

explanation

In some emergencies, you may have to drive off the road. It may be less risky than facing an accident with another vehicle. Most shoulders are strong enough to support the weight of a large vehicle and, therefore, offer an available escape route. [California Commercial Driver Handbook]