What are the two positions of mechanical point indicators and their meanings?

The correct choice conveys important information about the positions of mechanical point indicators and their respective meanings in rail operations. The position at a 45-degree angle indicates that the points are set and locked for mainline use, which is crucial for ensuring the safe routing of trains onto tracks that will lead to higher-speed mainline operations. This also communicates to train crew and operators a clear indication that the mainline points are properly aligned for safe travel.

The horizontal position signifies that the points are set for siding use. This is important in rail systems as it indicates that the track is directed away from the mainline, typically where trains can be shunted or stored safely without interfering with the primary flow of traffic on the mainline track. This clear distinction helps prevent potential accidents by ensuring that all personnel involved are aware of how the points are set and the intended path of the train.

In summary, the 45-degree position represents a secure setting of points for mainline use, while the horizontal position indicates that the points are configured for siding, providing essential guidance for operational safety and efficiency.