What is the maximum allowable difference in curve worn rail head width on the gauge side?

In thermite welding and rail maintenance, ensuring the proper geometry of rail components is crucial for safety and performance. The maximum allowable difference in curve worn rail head width on the gauge side is specified to maintain the integrity of the rail and to ensure smooth operation of trains.

The correct choice of 1/8 inch reflects the standard tolerance allowed in rail components, which is necessary to avoid excessive wear and ensure proper alignment and tracking of the train. This tolerance helps to maintain the safety and efficiency of rail operations by preventing issues such as derailments or increased wear on wheels and other rail components.

The other options represent either too great of a variation in rail width or are not typically acceptable tolerances in the industry. This focus on maintaining a small allowable difference is critical to ensure that rail services operate within safe and efficient parameters, enhancing durability and reducing maintenance frequency.