Final answer:
The optimum following distance behind large vehicles is typically the '3-second rule,' but it's often safer to have a gap of 4 or 5 seconds. Safety when crossing a road also depends on the speed and distance of oncoming cars and the pedestrian's ability to cross the street quickly enough.
Step-by-step explanation:
The optimum distance when following a large vehicle, such as a truck, is often referred to as the '3-second rule' which means that at any speed, you should be far enough behind the vehicle in front of you so that you will take at least three seconds to reach the same spot that vehicle is passing. However, many driving safety experts recommend increasing this distance to 4 or 5 seconds when following large vehicles to give you a better view of the road ahead and provide additional stopping distance. The distance you need to leave depends on several factors, including your speed, the truck's stopping distance, and road conditions.
When considering the safety of crossing a road with an oncoming vehicle, you need to take into account both the distance of the vehicle and your ability to cross the street safely. For example, if a car is 28 meters away, equivalent to 8 car-lengths, and you need to cover 4 meters to cross safely, you should ensure you have sufficient time to cross before the vehicle reaches you. This depends on the car's speed, your walking speed, and conditions such as road wetness or visibility.
In towns and cities with a speed limit of 60 km/h, remember that the width of the road and the distance a car covers per second can vary. It's crucial to judge both your ability to cross and the vehicle's speed accurately to ensure you are not in danger. Always err on the side of caution when judging the distance and speed of oncoming vehicles.