Construction started on the 10-station line in February 2011 and it was originally due to open in September 2013, but completion was delayed by the insolvency of one of the civil engineering contractors.

The new line has cost around €64m, with 36.5% of the funds coming from the German federal government, 34.5% from the state of Lower Saxony, 8% from the state of Bremen, and 16.5% from the municipal government in Lilienthal. The existing tram fleet is used to operate the additional services.

Line 4 (Bremen-Arsten – Domsheide – Main Station – Borgfeld – Falkenberg) services will operate a 15-minute frequency off peak (more at peak times) and journey times of 37-40 minutes are planned between Falkenberg and Bremen Main Station.

The new line is the culmination of network expansion to the north of Bremen which has resulted in the Line 4 route being built in three stages, the previous two being Kirchbachstrasse – Horner Mühle, which opened in 1998 and Horner Mühle – Borgfeld which was completed in 2002.