What defines Restricted Speed?

Restricted Speed is defined as the speed that allows a train to stop within one half of the range of vision. This definition is critical because it ensures safety in scenarios where a train may encounter an unexpected obstruction or signal. By maintaining a speed that allows for such immediate stopping capability, the railway system helps to prevent accidents and ensures that the crew has adequate reaction time to any unforeseen circumstances within their line of sight.

In contrast, the other options provided do not accurately describe Restricted Speed. Being greater than 20 MPH outside interlocking limits does not align with the concept of Restricted Speed, which emphasizes caution and the ability to stop quickly. The prioritization of adherence to schedules does not correlate with the safety-focused nature of Restricted Speed. Moreover, adjusting speed according to passenger comfort is not a factor in defining Restricted Speed, as this term specifically pertains to operational safety and visibility rather than passenger experience.