Works on or near the rail infrastructure can be carried out under one of four safety regimes:

Regime A.
Regime B.
Regime C.
Regime D.
Works can only be carried out in any one safety regime at a time.

Before start of the works it should be clear for all personnel under which regime the works will be carried out. Each regime has its own set of safety rules. The safety regime is determined by risk analysis carried out beforehand.