Maintenance work on most Danish railway lines is done by Banedanmark, a state-owned company that also allocates tracks for train operators.

Goods transport is mainly performed by DB Schenker Rail, although other operators take care of a significant portion of the non-transit traffic.

The network was extended by new construction and by acquisition of the privately operated lines from Silkeborg to Herning (1 November 1879) and from Grenaa to Randers and Aarhus (1 April 1881).

General-purpose electric propulsion was adopted quite recently in Denmark; the political decision to electrify the main lines was made in 1979.

The system is used on the main line from Sweden through Copenhagen to Fredericia, and from there to Padborg and the German border.

At least the route Fredericia-Ålborg must be electrified in order to run electric passenger trains between Jutland and Copenhagen.

[13] In September 2013 the government reached a deal with the Danish People's Party and the Red-Green Alliance (Denmark) to use additional oil taxes to create a train fund.

This would allow for travel between the cities of Copenhagen, Odense, Esbjerg, Aarhus, and Aalborg in four hours.

[14] On 29 May 2015 Banedanmark announced a 2.8 billion DKK (€375 million) contract to have Aarsleff-Siemens electrify 1300 km of tracks before 2026.

The City Circle Line is an entirely underground 15.5 km loop through central Copenhagen and Frederiksberg with 17 stops.

With the City loop opened, the Metro expects that its ridership should almost double from its 2016 levels to 116 million annual passengers.

The Sydhavn line will terminate at Ny Ellebjerg where it will create a new regional rail transport hub by connecting the metro system to the S-train network, regional trains, and long-distance trains on the current lines and the upcoming high speed Copenhagen-Ringsted railway.

On 8 May 2012, the Danish Parliament approved the construction of the first line; work to build Phase 1 commenced during September 2013.

It was originally planned to open in August 2016, but this was delayed, in part due to legislative issues in relation to railway safety.

Two types of rolling stock have been operated over the first line, conventional trams which are slower and restricted to only running along some parts of the route and hybrid tram-trains that can be operated on the conventional heavy rail network, the latter being used for the long-distance services.

Railway undertakings currently operating in Denmark: As part of ongoing plans for high-speed rail in Denmark, new corridors and lines are or were being planned: The following map shows the year in which ERTMS will be implemented on various sections of railway.

The main connection is over land at Padborg, which carries ICE, intercity and regional trains to Hamburg, and used to carry EuroNight and CityNightLine trains to Amsterdam via Cologne, Basel via Frankfurt, Munich via Nürnberg, and Prague via Berlin.

The Fehmarn Belt Fixed Link is a planned connection across the Fehmarnbelt between Denmark and Germany.

[42] Due to delays in delivering Talgo 230 equipment,[43] DSB in 2023 rented UIC-Z wagons from Deutsche Bahn.