As a domain expert in railway infrastructure, I'd like to shed some light on the use of stones on railway tracks. The stones you're referring to are actually a critical component of the track bed known as ballast. The role of ballast is multifaceted and essential to the stability and longevity of the railway system.

Firstly, ballast serves as a supportive structure for the cross ties (also known as sleepers), which in turn support the rails. The cross ties are typically made of wood, concrete, or steel and are laid perpendicular to the rails. They distribute the load from the rails over a larger area of the subgrade, preventing the rails from sinking into the ground.

The stones used for ballast are carefully selected for their size, shape, and durability. They are large enough to prevent them from being easily displaced by trains passing over them, yet small enough to allow for some movement, which is crucial for maintaining the flexibility of the track.

One of the primary functions of the ballast is to distribute the load from the trains evenly across the track bed. This prevents the formation of localized high-stress areas that could lead to the deformation or failure of the track.

Another important aspect of ballast is its role in drainage. Railway tracks are subject to various weather conditions, and it's essential that water does not accumulate around the base of the track. The voids between the stones allow for water to drain away quickly, preventing the subgrade from becoming waterlogged and unstable.

The ballast also helps to maintain the correct alignment of the track. As trains pass over the rails, the dynamic forces can cause the rails to shift slightly. The stones in the ballast can move slightly to accommodate these shifts, but they also provide resistance that helps to keep the rails in their proper position.

In addition to these functions, ballast plays a role in thermal regulation. Railway tracks expand and contract with temperature changes. The ballast allows for this expansion and contraction without causing the rails to buckle or become misaligned.

The process of laying ballast begins with preparing the subgrade, which is the ground upon which the track is built. The subgrade must be compacted and leveled to ensure a stable foundation. Then, a layer of larger stones is laid down to form the base of the ballast. This is followed by a layer of smaller stones, which are packed tightly to provide a solid and even surface for the cross ties.

The use of ballast is a time-tested method that has been employed for over a century. It's a simple, yet effective solution to many of the challenges faced in railway construction and maintenance. By providing support, drainage, alignment, and thermal regulation, ballast plays a crucial role in the safe and efficient operation of the railway system.

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The crushed stones you see alongside railroad tracks are what is known as ballast. Their purpose is to hold the wooden cross ties in place, which in turn hold the rails in place. ... The answer is to start with the bare ground, and then build up a foundation to raise the track high enough so it won't get flooded.Sep 27, 2013read more >>