What determines the maximum speed to which a train may accelerate?

The maximum speed to which a train may accelerate is primarily determined by the position of the master controller handle. This controller effectively governs the amount of power delivered to the train's motors, allowing the operator to control acceleration and manage speed. When the handle is positioned appropriately, the train receives the necessary power to accelerate up to its maximum speed, taking into account various factors such as track conditions and operational limits.

While other factors, such as signal aspects or train type and weight, can affect speed management in broader contexts, the direct control of acceleration stems from how the master controller is set by the train operator. Therefore, understanding how to effectively use the master controller is crucial for maintaining safety and efficiency within permissible speed limits.