Trains via Jolarpettai to Save Time With New Signalling, Remodeled Yard

Punctuality of trains passing through Jolerpettai Jn. of the Southern Railway will now improve thanks to major yard and signalling upgrades at the station.

A significant bottleneck for Southern Railway’s train operations, the Jolarpettai (railway code JTJ) yard stood out in its old design, totalling 4 km in length, eating up travel time as trains had to crawl through most part of the yard.

Finally, a few months ago, after hectic planning, Southern Railway began work on remodelling the track geometry at the signalling at the JTJ yard.

The work was carried out in two phases.

Works Carried Out in Jolarpettai (JTJ) Yard

  • Elimination of three 1 in 8.5 diamond crossings. Diamond crossings have traditionally been major bottlenecks since the speed over these needs to be restricted. Here the curvature was especially sharp, hence elimination of these crossings will directly result in increased speeds. As a matter of policy, the Indian Railways have decided to eliminate diamond crossings wherever feasible.
  • Conversion of two 2.2 degree reverse curves into simple curves
  • Provision of 3 sand humps to isolate the through goods lines and common loop from the mainline
  • Change over to electronic  interlocking from the aged route relay interlocking, the work included the provision of the main electronic interlocking cabin,  auxiliary interlocking cabins and three object controller Huts

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  • Creation of facilities to receive and despatch trains simultaneously towards Bangalore. With remodelling of the yard, it is now possible to deal with several trains simultaneously through the provision of additional sand humps and dead ends.
  • Replacement of 40 double-end points and six single-end points with  new point machines
  • Renewal of 42 main signals and 24 subsidiary signals
  • Replacement of 165 track circuits
  • Provision of BPAC(Block Proving by Axle Counter) with HASSDAC(High Availability Single Section Digital Axle Counter) at Salem and Bangalore ends. This will considerably improve average speeds and movement of trains following each other as block working through axle-counter arrangement is not only very safe but speedy too.
  • Change over to electronic  interlocking from the aged route relay interlocking, the work included the provision of the main electronic interlocking cabin,  auxiliary interlocking cabins and three object controller Huts
  • Interlocking of the last non-interlocked LC gate in Chennai division has been completed during this work.

“This work increases the speed of non-stop trains passing through JTJ from the present 15 kmph to 110 kmph for trains going to the Salem direction,” says an official involved in the yard upgradation. “Trains passing through towards Bengaluru can change tracks at 30 kmph and run through at 60 kmph.,” he added.

Switch from Legacy RRI to New EI Signalling

Moreover, the legacy signalling system, called Route Relay Interlocking (RRI), has been replaced with the latest Electronic Interlocking (EI) technology. This increases safety and reliability of the entire signalling system.

The old RRI was composed of thousands of electromechanical relays. These components use more power and operate relatively slowly. Relay interlocking systems also generate a lot of heat and need more space.

Southern Railways has now upgraded Jolarpettai yard to Electronic Interlocking (EI). This system is now becoming the norm for all interlocking work over the Indian Railways.

The Benefits of Electronic Interlocking Systems

All the EI systems are of the dual-redundancy type with dual control VIsual Display Units (VDUs). If one system fails, the other system can continue to operate. EI systems take less time to install and commission; they are assembled in prefabricated racks at the factory. Besides, the testing of all EI is automated.

JTJ junction has a huge yard stretching out to four kilometres. SR has set up a variant of EI called the ‘Distributed EI’. In this system, the yard has small buildings at strategic locations in which a subsidiary EI unit is installed. In addition to the EI, the hut will also have a robust power supply installation and other gears for the effective functioning of the signalling system.

The EI in this hut communicates with the main EI and constantly updates the status of the signalling gears controlled by the hut. The communication channel is a dual-redundant fibre optic link.

At the same time, the cables of all controlled signalling gears are terminated at the EI hut. This considerably reduces the length of the cables which need to be laid. In the legacy installation, every cable needed to be brought to the RRI location.

Due to the distances involved, there was a considerable voltage drop along the cable. This issue will now be eliminated due to the proximity of the huts with their respective controlled signalling gears. It will also be easier now to address cable fault issues as the cable lengths are now shorter.

Overall, this move shaves a whopping 20 minutes off the schedule for a Salem-bound passenger travelling on a train that does not stop at JTJ. For trains stopping at JTJ, some time will still be saved due to these upgrades.  

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  1. Great. The diamond crossing at Pune is also a great concern for the train which comes from Mumbai. There was a plan to change but till now no action. Once this done, there will be great change in functions. Will look into.

      1. The core competence and mantra of this team lies in the process of enabling and motivating, helpers with tremendous capability , to deliver a state of art ,next generation product

  2. Wonderful post, with a lot of technical detail. The information here will be of interest not just to a discerning passenger who frequently passes through JTJ, but also to any ‘Railfan’. My grandfather has been a Station Master in all the intermediate junctions in the Madras-Bangalore route, with the longest stint in JTJ during the 1960s. I always felt an emotional connect with the Madras-Bangalore route, and particularly with JTJ.

    Interesting to note that the new signaling control equipment has been commissioned complete with ‘pooja’ and ‘garlands’. Very touching indeed 🙂

    Request to the author: It would also help if the photographs are also captioned with brief descriptions. I could make out the absence of the diamond crossing and the inclusion of the point-switch in the second of the two photos showing the tracks, but not all readers may be able to distinguish the change that easily.

    Immensely enjoyed reading the article…!

  3. Thats great work which is completed in record time

    I have a question. Why not UP trains speeded up in similar way. There can be 110 KMPH line for trains coming from bangalore (non stop at JTJ) towards KPD. Why no such similar attempts was planned for UP trains from Bangalore

  4. Appreciate the Commitment of Team SR during the Current Difficult Times. Execution of Complex Yard Remodelling Works with focus on Eliminating Bottlenecks and Introduction of More Reliable & Safe Advanced Interlocking and Block Signalling Systems is Always a Challenge. Improvements in Yards for the Up Direction may be undertaken in subsequent works.

  5. Sir. After commissioning of EI system, for maintenance and attending failure, doing alteration etc of the system at particular station, Railway depend on OEM till the end of codal life. Staff to be trained to attend the failures, etc needs to fill the hole in the exchequer.

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