Final answer:
You must stop at least 5 meters away from the closest rail at a railway crossing when signal lights are activated for safety reasons.
Step-by-step explanation:
When approaching a railway crossing and the signal lights are activated, you must stop at least 5 meters away from the closest rail. This rule is crucial for safety, ensuring that there is ample space between the vehicle and the tracks to prevent accidents should a train approach. In regards to whether it is safe to cross the road when a car is 28 meters away, we would need more information such as the car's speed and the pedestrian's walking speed to make a determination.