Way of access to the machines: what norms must be respected?

During the study of a safeguard, it is always necessary to consider the areas for the access for eventual maintenances to the machines.

It is obvious that there are different possibilities to permit to an operator to work in a safe way.

To pre-dispose the access in high using platforms or stairs is one of the most used solutions.

But are there also some indications or some rules to be considered in order to make all correctly?