This high-speed bypass at Wismar (HSL) is part of a series of proposals for the triangle Hamburg – Berlin – Szczecin. Read first the introduction: New rail infrastructure north of Berlin.
This is not a proposal for a separate line, it is an alternative route for the earlier proposed Lübeck – Rostock HSL, without a station in Wismar. Because it bypasses Wismar, an alignment along the Autobahn A20 is an option for this variant. The connection from Schwerin would also be easier, following the existing line through Bad Kleinen.
A fast Wismar – Rostock service would still be possible, with a relatively short connecting line from Wismar to the A20. Trains from Lübeck could use the HSL and enter Wismar from the south, although the route is less direct. The main disadvantage is that Wismar would have no through fast services.
As described earlier, the line from Lübeck Hauptbahnhof to Grevesmühlen would be upgraded as Ausbaustrecke, with some new sections. From Grevesmühlen, a new section would run east, to join the A20 near Barnekow. It would cross a lake, and avoid some ridges, with local elevation differences of about 40 m.
South of Wismar, the HSL could be built alongside the Autobahn, but the curved alignment would limit speeds. The new line might have a separate alignment between Barnekow and Kreuz Wismar (shown in orange), and possibly between the junction and Nevern. (A completely separate alignment to Rostock, entirely north of the A20, is also possible).
The new line from Lübeck would have a west-to-north curve (shown in blue), onto the existing Schwerin – Wismar line. A new exit line, toward Rostock (in green), would run from the outskirts of Wismar – passing around Dargetzow to join the A20 alignment near Kreuz Wismar.
There would also be a connection from the Schwerin direction onto the new line (in purple), for fast Schwerin – Rostock trains. It could follow the existing line through Bad Kleinen, or it might bypass that junction.
East of Nevern, the HSL could follow the A20 to Heiligenhagen, and then turn away toward Rostock. The junction with the existing single-track line from Wismar would be east of its crossing with the B103. The alignment inside Rostock needs upgrading, as mentioned earlier.
The new line would be approximately 115 km long, from Lübeck to Rostock. With a separate rail alignment Wismar – Rostock – not along the A20 – it would be slightly shorter. Length is not the main factor in the choice of Lübeck – Rostock alignments. An alignment along the A20 might be shorter if it avoided central Wismar – but that advantage might be lost, by following the curves of the Autobahn. More important is that a bypass of Wismar is easier to build, than a central-area tunnel.