What is the Main Parts of a Successful Safety System ?

The main and the most important part is the managerial part which consists of general statement of intent, organisation section and the arrangement section, every company shows their commitment towards H&S via their policy but what misses out later is their co-operation and for me if there's good co-op between the management (engineering side) and the safety team then that's it you will do great with the safety and health of every personnel on the site.    

Every Parts needs to be active for a successful Health & Safety Management  system  just like our body parts. but if you are asking about the main part which  off course is a Organization's EHSS Policy like our brain in our body.