in 1989, the u-bahn line e (now u 5) was extended over the vnk line to wuhletal station. it is the only station in berlin where it is possible to transfer between s-bahn and u-bahn services on the same platform. in 1992, birkenstein station was opened between mahlsdorf and hoppegarten. at the same time a second s-bahn track went into operation on this section.