What is the maximum gradient at which a railway track may be laid called?

The maximum gradient at which a railway track may be laid is referred to as the ruling gradient. This term is essential in railway engineering as it defines the steepest incline that trains can safely traverse under normal conditions without significant risk of operational issues, such as excessive fuel consumption or inability to climb the slope. The ruling gradient takes into account various factors including the power of the locomotives, the weight of the trains, and the overall design of the railway system.

Having a well-defined ruling gradient is crucial for maintaining efficiency and safety in railway operations. It ensures that trains can travel at acceptable speeds while managing the forces acting against them on inclines. The ruling gradient is carefully calculated during the design phase of railway construction to optimize performance while balancing the terrain's natural topography.

Other terms like steep gradient, emergency gradient, and standard gradient may relate to specific contexts within railway engineering or operational practices but do not specifically define the maximum safe gradient for track laying. Thus, the ruling gradient stands out as the correct and most applicable term in this scenario.