Have you ever noticed something unusual while travelling by train or metro? Traditional railway tracks are usually surrounded by layers of crushed stones, but many metro tracks appear to rest directly on solid concrete. Why do engineers use thousands of stones on one type of track while leaving them out of another? The answer lies in the science of railway engineering. Both systems are designed to carry heavy trains safely, maintain the correct position of the rails and withstand repeated vibrations. However, they achieve these goals through different construction techniques. The stones beneath conventional railway tracks are not placed there randomly. They form a carefully designed foundation that supports the entire track structure. Many metro systems, on the other hand, use concrete-based track designs that provide stability without loose stones. Understanding this difference reveals how engineers adapt railway infrastructure to different environments, from open countryside to under...