If a heavy truck suffers a mechanical breakdown on a national road, what is the driver's first immediate safety action?

1. Leave the vehicle to search for a local mechanic shop
2. Activate the hazard warning lights (double signals) and move the vehicle safely to the shoulder
3. Place Early Warning Devices (EWDs) in the middle of the road to block oncoming traffic
4. Attempt to repair the vehicle engine while parked in the active driving lane