Final answer:
In heavy rain when windshield wipers can't keep up, signal and pull over safely until visibility improves to prevent accidents.
Step-by-step explanation:
If it is raining so heavily that your windshield wipers cannot keep up, you should signal, pull over to a safe location, and wait until the rain subsides enough for you to drive safely.
It is vital for your safety and the safety of others on the road that you have clear visibility. If you continue to drive in such conditions, you're more likely to be involved in an accident due to impaired visibility and potentially hazardous road conditions.