Horrifying pile up on the motorway

[glatt]

If traffic is heavy, then it's not about you and the driver in back of you, it's about you and the entire stream of traffic behind you. You can actually cause an accident in heavy traffic just by braking suddenly. That accident may not include you, it may be 4 or 5 cars behind you as each car behind you brakes increasingly hard. Your responibility in heavy traffic is to do nothing that causes the people behind you to over react. That means you should leave enough space in front of you to gradually stop, and give the car behind you some warning.