Sequence of the Signals
From the driver’s viewpoint, while entering the block section he sees the following signals
Advance Starter at Dungri-Already explained in detail above. This is usually a Two- Aspect signal showing Red or Green. But where block sections are short, this signal may be of three or four aspects and may also take the place of the Valsad Distant. In other words the Valsad distant signal may be combined with the Dungri Advance Starter.
Up Distant signal of Valsad- As explained in previous paragraphs, the Home Signal is the very first signal encountered by the driver at the station but the Home is a Stop signal and might be displaying the Danger aspect. Now an important rule of railway signalling is that a driver must never be shown the danger aspect directly but whenever he approaches a danger signal, the preceding signal must show a Caution aspect—that is the Yellow aspect. This will warn the driver that he is approaching a danger signal and will ensure that he has his train well in control before he approaches the Home at danger. Hence a permissive signal known as the Distant Signal is provided a full braking distance in rear of the Home signal. This maximum braking distance is considered to be 1000 meters on the IR. Hence the Distant is provided at a distance of 1000 meters form the Home. As the Distant is a permissive signal, the driver is never confronted by a danger aspect on a distant signal. If the Home at Valsad is displaying a less restrictive aspect then the Distant also steps up to green correspondingly.