What is the difference between points and crossing in railway?

The Unsung Heroes of the Rails: Demystifying Railway Points and Crossings

The rhythmic clatter of a train traversing the tracks is a sound many find familiar. But have you ever considered the complex mechanics that guide these metal behemoths along their winding journeys? Two crucial components, often working in tandem, are railway points and crossings. While they both contribute to a train's ability to navigate the network, their functions are distinct. Understanding the difference between them provides a fascinating glimpse into the ingenuity behind railway infrastructure.

Points: The Decisive Diverters

Think of railway points, also known as switches or turnouts, as the decision-makers of the railway system. Their primary function is to actively divert a train from one track to another. They achieve this through a clever mechanism involving movable rails, typically called switch rails or point blades. These blades are tapered and designed to fit snugly against the main running rails.

When a train needs to continue straight ahead, the switch rails are aligned with the existing track, providing a seamless continuation of the journey. However, when a change of direction is required, the switch rails are moved laterally. This movement creates a gap on one side, guiding the train onto a diverging track. This action effectively "switches" the train's path. The points are controlled remotely from signal boxes or control centers, ensuring precise and safe track changes.

Crossings: Accommodating the Unavoidable Gaps

In contrast to points, crossings (also known as frogs) are not responsible for actively changing a train's direction. Instead, their role is to allow the wheel flanges of the train to pass safely over a point where two rails intersect. This intersection inevitably creates gaps in the running surface, which, without a proper crossing, would cause the wheels to drop or potentially derail.

The crossing fills this gap with a specially designed structure that allows the wheel flanges to pass through without causing damage to the wheel or the track. They are fixed components, meaning they don't move or switch like points. Their primary function is to provide continuous support for the wheels as they roll over the intersecting rails.

The Turnout: A Collaborative Effort

It's crucial to understand that points and crossings often work together as part of a larger assembly called a turnout. A turnout is the complete mechanism that allows a train to transition from one track to another. It includes not only the points and the crossing but also the lead rails.

Lead rails are the connecting rails that gradually diverge from the main track to the diverging track, leading the train smoothly towards the crossing. The points initiate the change in direction, the lead rails guide the train along the diverging path, and the crossing allows the wheel flanges to navigate the intersecting rails safely.

In summary:

• Points (Switches): Actively divert trains from one track to another by moving switch rails. They change the train's direction.
• Crossings (Frogs): Allow wheel flanges to pass safely over intersecting rails, providing continuous support and preventing derailment. They accommodate the unavoidable gaps in the rails.
• Turnout: The complete assembly, including points, crossings, and lead rails, that enables a train to change tracks.

By understanding the distinct roles of points and crossings, we can appreciate the sophisticated engineering that underpins our railway networks. These seemingly simple components, working in harmony, ensure the safe and efficient transportation of passengers and goods across vast distances. They are, without a doubt, unsung heroes of the rails.