What is the maximum allowable speed on a curve determined by?

The maximum allowable speed on a curve is primarily determined by the car-borne map, as it provides essential parameters related to the railway's geometry, including curvature radii and superelevation. This information is critical for ensuring safe operations, as it helps engineers assess how speed interacts with centrifugal forces at various points along the curve.

A car-borne map includes data that can influence the train's dynamics, such as how sharp the curve is and the elevation variance, which inform the design and operational limits for train speeds. The map serves as a practical tool during the train’s operation, allowing engineers to adjust their speed accurately according to the specific track conditions laid out in the map.

While speed limits from nearby stations and weather conditions can have an impact on overall train operations, these factors do not directly determine the maximum allowable speed on a curve itself. Similarly, the type of train may influence handling and performance but does not define the curvature limits imposed by the rail infrastructure. Thus, while other factors play a role in safe train operation, they do not specifically set maximum speeds on track curves.