To safely exit a motorway, it is important to **merge into the deceleration lane as soon as possible**. This is due to several reasons:

- **Traffic safety and flow**: By entering the deceleration lane as soon as possible, it allows traffic on the motorway to continue flowing without interruptions. This is crucial to avoid being an obstacle for vehicles that continue on the motorway at high speed.

- **Speed adaptation**: By merging early into the deceleration lane, there is more space and time to **gradually reduce speed**. This is important to avoid sudden braking that could cause accidents or dangerous situations.

- **R.S.M. safety rule**: This rule emphasizes the importance of performing maneuvers safely, at the appropriate speed, and without endangering other vehicles. By entering the deceleration lane as soon as possible, this rule is followed by allowing a controlled and safe speed reduction.

In summary, merging into the deceleration lane as soon as possible is essential to maintain safety and traffic flow on the motorway, allowing for controlled deceleration and avoiding being an obstacle for other drivers.