The small rolling resistance and the consolidation of transport needs remain the foundation of the railway's success to this day. The superstructure, meaning the railway track, unjustly leads a somewhat overlooked existence compared to locomotives and carriages. The rail system is subject to the highest demands. It must be laid precisely, withstand weather influences, and keep high-speed trains securely on track. Precursors to the iron track include the cart tracks of the Romans and the guided tracks in mines. In the 1870s, the mushroom-shaped rail profile that is still in use today was defined. From 1885, the double switch became the standard. Due to electrification, locomotives became heavier and ran faster. The demands on the superstructure increased. The SBB systematically conducted tests at the Gotthard.