Maintenance work on most Danish railway lines is done by Banedanmark, a state-owned company that also allocates tracks for train operators. The majority of passenger trains are operated by DSB, with Arriva operating on some lines in Jutland. Goods transport is mainly performed by Railion, although other operators take care of a significant portion of the non-transit traffic.
Denmark is a member of the International Union of Railways (UIC). The UIC Country Code for Denmark is 86.
The maximum speed allowed on main lines is generally 180 km/h, with less trafficked lines usually allowing between 75 and 120 km/h; the speed may be lowered in places due to the condition of the track. While wooden sleepers are used on sidings and branch lines, concrete sleepers are the norm on all main lines; the common two-block concrete sleepers are now being phased out in favour of monoblock ones.
The age of the tracks in Banedanmark's network has become increasingly problematic in later years. A 2002/03 analysis of Banestyrelsen's (now Banedanmark) network states that the average age of the track is too high, with a present average age of 24 years compared to the recommended 20 years.
The S-train network in Copenhagen operates at 1650 V DC, supplied from overhead lines; the Copenhagen Metro uses 750 V DC, supplied from a third rail.
Since there are heavy delays (several years) with the construction of the new diesel multiple unit IC4, many debators argue that it is better to electrify major railways and purchase electric multiple units instead, since that is a much more well-known product among the manufacturers. At least the routes Fredericia-Ålborg and Kolding-Esbjerg must be electrifed in order to run electric passenger trains between Jutland and Copenhagen.
Connections to Germany and Switzerland involve a DSB train, which is put onto a ferry and arrives in Germany in Fehmarn and then proceeds via Lübeck to Hamburg (Vogelfluglinie) and the NachtZug leaving from Hagen, Munich, Zürich and Amsterdam and arriving in Copenhagen at 10 am cutting through mainland Denmark.