Final answer:
The guidelines for safe following distance in good conditions is the 3-second rule. It ensures sufficient time for drivers to react and stop if the situation requires. Safety also depends on environmental and situational factors.
Step-by-step explanation:
The guidelines used for determining following distance in good conditions recommend maintaining a 3-second distance from the vehicle in front of you. This 3-second rule helps to ensure that you have enough time to react and stop safely if necessary. The distance you should keep will increase proportionally if the conditions deteriorate, like in cases of bad weather, poor visibility, or when you are driving a larger vehicle which may require more time to stop. When a car approaches and is 28 m away, whether it is safe to cross depends on various factors including the speed of the car and the time it takes for you to cross the road.