To merge onto a road using an **acceleration lane**, it is crucial to ensure that the maneuver can be performed safely **at the beginning of the acceleration lane**. This is due to several reasons:

- **Early observation**: By starting at the beginning of the lane, you have the opportunity to observe the traffic on the main road and assess if it is safe to merge. This allows you to make informed decisions about when and how to enter the road without endangering other drivers.

- **Yielding**: It is important to yield to vehicles already on the road. If you wait until the end of the acceleration lane, you might find yourself in a situation where there is not enough space or time to merge safely, which could force you to stop abruptly or perform a dangerous maneuver.

- **Speed adaptation**: By starting the maneuver from the beginning of the lane, you can gradually adjust your speed to match that of the vehicles on the main road, facilitating a smooth and safe merge.

- **Avoid being an obstacle**: Starting from the beginning of the lane gives you more time and space to ensure that you do not become an obstacle for vehicles already traveling on the road.

In summary, starting the merging maneuver at the beginning of the acceleration lane is essential to ensure the safety of both yourself and other drivers.