Line no. 18 was a result of the union between "Frederiksberg Sporveje" and "De Kjøbenhavnske Sporveje" in 1919.

The line was going from Frederiksberg to Valby Railwaystation in Copenhagen.

In the first years the line were using the streetcars of the double-decker type from the former streetcar company - Frederiksberg Sporveje.

Later the cars were of the common type used all over Copenhagen by the streetcar company.

The last day for the line to be a streetcar line was July the 20th 1958. The nickname of the line was: The Rocking Horse because there was a section of the line, where the streetcar always began to rock.