I.B.S. - Noble Idea of Improving Track Utilization !
Imagine yourselves being in an train which is in an Absolute Block Section Territory.Your train is waiting for another Superfast Train to overtake it.The overtake is done and that Superfast train has entered Block Section ahead.
But as the Working Rules of Absolute Block System say , another train cannot be sent into the same Block Section unless line clear has been given by station in Advance- your wait starts.The wait is less - somewhere around 10 minutes or so if the distance between...
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two consecutive stations is around 6 km.
What if the distance is more than 6 kms ?In India distance between most of the stations is usually more than 6 kms. Would this mean the train is made to wait for 15-20 minutes ? The answer to this question is 'NO'.This is the point where Intermediate Block Section comes into picture.
If the distance between two stations is more than 6 or 7 kms , the bigger block section is divided further into small block section of 3 , 4 or 6 kms known as Intermediate Block Section.The Signal guarding the exit from IB Section to another I.B. Section is the I.B. Signal.It is usually controlled by Station in Rear.However sometimes a Block Hut or Halt Station controls its Aspect.
For e.g. - Thansit on N.E. Line branching out of Kalyan acts as Halt Station because the distance between Atgaon and Khardi is 12 kms!
Seen in the image is the Intermediate Block Signal between Khadavali and Vasind Stations in the Off Aspect.Also notice the Axle Counter and Track Magnet which serves for Block Proving and Auxillary Warning System respectively.The signal was pulled Off for horribly late running 11058 Amritsar - Mumbai C.S.T. Pathankot Express.The distance between Khadavli and Vasind is 9 kms.Therefore the long block section is divided into two IB sections of 4.5 kms.The location of this signal is close to Bhatsa River Viaduct.
Once a train in advance has crossed this signal , the Starter and Advanced Starter of Khadavali can be pulled off . As soon as the train has completed the Block Overlap for Vasind , this IB Signal can be pulled off (if any train is about to be received) .The working of IB Signal is similar to that of Starter Signal.It is the first and Last Stop Signal for IB Section.Thus an IBS helps to improve the track utilization and is very much useful where the frequency of trains is around 10 minutes.Incase of Speed Restriction ahead it can display Caution Aspect.The normal Aspects are similar to that of an Advanced Starter.
Khadavali and Vasind stations fall on KALYAN - KASARA route of North East Line.The section between Kalyan and Titwala works entirely on Automatic Block System.
The section ahead works on Absolute Block System
On board 2 hours late running Mumbai C.S.T. - Hazur Saheb Nanded Tapovan Express with #21877 KALYAN WCAM-2 A.C. 6P Chocolate Boy in lead.
Time - Around 9:30 am .
Location - Between Khadavli and Vasind.
Date - 7 th December ,2016.