The project will extend the line by 3.4km from its current terminus on Waldinghoferstrasse in Bergfelden to the Bergfelden border crossing serving a park-and-ride station near the A35 motorway before terminating outside the mainline station in Saint Louis.

Services will operate at 7-8 minute intervals as far as the border, with trams running to Saint Louis every 15 minutes.

The SFr 98m ($US 101m) extension is due to open at the end of 2017.

Last December BVB opened its first tram line into Germany, with the extension of Line 8 services from Kleinhüningen to Weil-am-Rhein.