In 2004, the Danish Accident Investigation Board for aviation and railway (AIB) was established.
From November 1971 until July 1996, a dedicated accident investigation group within the Danish State Railway performed safety investigations of serious accidents.
Via establishment of the Railway Inspectorate (an independent authority for all railway activity in Denmark) in 1996, the task of performing independent safety investigations was transferred to the Railway Inspectorate.
In 2004, the responsibility and the authority of performing independent safety investigations was transferred to the AIB.
The Railway Unit of the AIB consists of three safety investigators - a head of the Railway Unit, a senior investigator and a safety investigator.