You notice an accident in the tunnel. What do you have to do?

You correctly identified the key steps to take when noticing an accident in a tunnel. According to German traffic rules, it is essential to switch on your hazard warning lights to alert other drivers and prevent further accidents. Additionally, you must inform emergency services using the tunnel's SOS telephone, as mobile phone signals may be limited and help can be dispatched quickly. While staying in your vehicle isn't mandatory in all cases, the most critical actions are to warn others and call for help using the designated emergency system. This ensures safety and a prompt emergency response in the confined environment of a tunnel.