Since September 2000, a popular initiative in Stormarn has been working for the improvement of the S4, today the RB 81. The initiative is currently basing their arguments on a feasibility study which was ordered by S-Bahn Hamburg GmbH in the year 2002, and in principle dusted off the plans from the 1960s. According to the study, the extension involves upgrading the line to proper S-Bahn standards, served by EMUs and the addition of extra stations. The first step would be the improvement of the line as far as Ahrensburg, with a further intended step being the continuation to Bad Oldesloe. Dual-system trains would be necessary for the new line like those used on the extension to Stade. A third rail would be built as far as Ahrensburg, from where the trains would use the existing tracks with overhead lines.