The safe following distance is one car length for each 10 miles per hour. If you are traveling at 40 mph, one should allow a minimum of 4 car lengths between you and the traveling object in front of you. Allow more room for a motorcycle in case they wipe out (fall and crash) in front of you.
3 seconds
At minimum 3 seconds. If the road conditions are adverse, it should be 5 seconds or more.
In clear weather conditions, 2 seconds.
A motorcyclist should be treated like a car and given the same distance - though due to the quick nature of their turns, 4-5 car lengths might be better.
It depends on the conditions but 2 - 3 seconds at least
Two seconds.
2 to 5 seconds, depending on what speed you are travelling and the weight of your vehicle. The faster you go or the heavier your vehicle is, the more distance you should have between vehicles. Check the time by taking note of some landmark such as a sign or overpass, and when the car in front reaches it, start counting seconds. When you pass that same landmark, stop counting. If you're doing city speeds (around 30mph/50kph), you should have 2 or 3 seconds between. At highway speeds (around 60mph/100kph), you should have more like 5 seconds between.
30 seconds
3 seconds
no but they need a lot of reflectors
Drivers should look 12 to 15 seconds ahead of their vehicle on city streets and ______ seconds ahead on freeways
20 seconds, or as far as you can see down the road.