On sight. Movement of a train whose journey takes place at such a speed as to be able to stop in a space not exceeding the unobstructed view. Therefore, the speed allowed with sight running, taking into account the braking space required for stopping the trains, is limited and entrusted to the driver. In the railway regulation, sight running is envisaged in particular cases, in particular line conditions and specific aspects of fixed signals, lack or limitation of safety conditions by apparatus, or for other events. In the case of sight running, required to pass a level crossing at open barriers or for which there is no control, speed limitation not exceeding 4 km/h is also provided
Link... for your business