Final answer:
You should be in the proper turning lane at least 100 feet from the intersection. This distance provides safety by allowing other drivers to anticipate your turn and accounts for the variables in stopping distance based on speed, reaction time, and road conditions.
Step-by-step explanation:
When preparing to make a turn at an intersection, it is important to be in the proper turning lane well in advance. While the exact distance can vary by jurisdiction, a common guideline is to be in the correct lane approximately 100 feet from the intersection. This allows for a smooth and safe turn, giving other drivers ample warning of your intentions to turn. When considering the physics of stopping distances, we understand that the total distance needed to halt a vehicle is dependent on factors such as speed, driver reaction time, and road conditions which might significantly increase the required distance. For example, if a driver is traveling at a certain speed and recognizes the need to stop, they must first react, which takes time. Then the vehicle begins the process of braking. The distance covered during the reaction time and the braking process can be considerable, especially at higher speeds or in poor road conditions. Therefore, being in the proper lane at least 100 feet from the intersection is a general safety measure which accounts for these variables to some extent. A safe distance to cross the road would then depend on factors such as vehicle speed, the observer's reaction time, and the distance from the oncoming vehicle.