Railways are built to follow Earth’s terrain, minimizing the grade/slope as much as possible. Consequently, they all follow Earth’s curvature. And many of them were built by explicitly accounting for the curve of the Earth.
Flat-Earthers claim that railroads are straight, and never built by accounting for Earth’s curvature. They are wrong. The leveling works were done in such a way to minimize the effect of Earth’s curvature. There are also multiple books describing railroad constructions where the curvature of the Earth is specifically accounted for.
- Field-book for Railroad Engineers – John B. Henck
- A Treatise on the Principles and Practice of Levelling: Showing Its Application to Purposes of Railway Engineering and the Construction of Roads – Frederic Walter Simms
- Charleston & Hamburg, A South Carolina Railroad and an American Legacy – Thomas Fetters
- Selected Problems of Determining the Course of Railway Routes by Use of GPS Network Solution – Władysław Koc, Cezary Specht
- Grade (slope) – Wikipedia