the 3 second rule
There are so many rear-end collisions these days maybe it's because people drive too close to each other.
Part of the Highway Code in the UK is a table of Breaking Distances... the amount of space you should be behind a car if travelling at such and such a speed, the proper distance giving you enough time to think and space to break safely without crashing into the next car.
But an easier way to do it, is by following the golden rule : "Only a fool breaks the 3 second rule!"
When the car in front passes a 'given point' eg a shadow on the road or a bridge or whatever, you say
"Only a fool…" to yourself.
If you reach the 'given point' before finishing the 'rule' you are too close.
Happy safe driving :D