What are the statutory requirements for forming an emergency corridor (Rettungsgasse) on Swiss motorways in congestion?

1. Vehicles must all pull onto the hard shoulder and stop their engines
2. Vehicles only form a corridor after hearing a siren directly behind them
3. An emergency corridor is only required in road tunnels
4. Vehicles in the left lane move as far left as possible, while vehicles in the adjacent right lane move as far right as possible, keeping the center corridor clear for emergency vehicles