Overview

• The EU Commission has provisionally withheld approval for the six-lane expansion of the Autobahn 643 between Mainz-Gonsenheim and Mainz-Mombach.
• Brussels found that proposed mitigation measures fell short of offsetting habitat loss in the Mainzer Sand Natura 2000 reserve and that alternative routes were insufficiently evaluated.
• The commission recommended that municipal, state and federal authorities reconvene to explore the ‘4+2’ model, which would open hard shoulders on the existing four lanes instead of adding two permanent carriageways.
• Mainz’s environmental councilor Janina Steinkrüger hailed the decision as confirmation of the reserve’s ecological value, while Rhineland-Palatinate transport minister Daniela Schmitt urged the federal government to back the full six-lane plan in Brussels.
• Stakeholders now face multilevel negotiations to reconcile stringent EU habitat protections with regional mobility needs on the vital Mainz–Wiesbaden corridor.