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

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• 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.

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“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.

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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.