Complex sentence: Only after the Lower Austrian State Railway Law was passed in 1895 did work begin on the project, and owing to the difficult terrain that the railway would have to cross, it was decided to build it to a narrow gauge.
Split into simpler sentences: Only after the Lower Austrian State Railway Law was passed in 1895 did work begin on the project. Owing to the difficult terrain that the railway would have to cross, it was decided to build it to a narrow gauge.