When driving on ice that has been cracked and refrozen, Elverum says you should cross the cracks at right angles. Don't park near them. There are cases in which a waterproof flashlight, for anyone trapped, can signal rescuers, and even help the victim find a way out. Snow, especially after rain, adds an enormous burden. Consider this when judging ice strength.
New ice is generally stronger than old.
Beware of rotten ice. Ice near shore is weaker. River ice will generally hold 15 percent less weight. Straight, smooth stretches tend to be safest. Beware of ice over river mouths.