Why are passengers strictly prohibited from remaining inside a broken-down passenger coach or standing near the vehicle on an expressway?

1. Disabled vehicles on expressways are highly vulnerable to secondary high-speed rear-end collisions by distracted or speeding traffic; all passengers must evacuate behind the outer guardrail immediately
2. Passengers standing outside take up room needed for spare tires
3. Expressway fresh air is harmful to passenger health
4. Passengers might accidentally wash the coach exterior