Purulia Express: লালপাহাড়ীর দ‍্যাশে যাবি? চিন্তা কিসের লো? বিকাল বেলা হাওড়া থেকে পুরুল্যা এক্সপেরেস পাবি। - Dip

For a brand new route, yes - track linking is pretty much the same as interlocking. However, when new tracks are constructed at a station, some of the existing interlocking arrangements have to be removed to restructure the system for adding the new lines. For example, in a single line section, usually the platform lines are interlocked in such as way as to allow bi-directional train movement. After the route is converted to a double line section. the bi-directional movement is no longer necessary and some points and signals no longer need to be interlocked. So, non-interlocking work is carried out and the related interlocking work for the new sidings and signals is also carried out. such non-interlocking is also done when there are signalling system upgrades.
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In a more straight-forward scenario, stations with mechanical (or partially mechanical) interlocking will have a system of rods and wires that interlock the signals and points. This is not a very flexible arrangement and the entire system has to be physically modified for adding any new routes through the station. So, when the system is upgraded to an electronic system (RRI or SSI), the physical interlocking is removed and the RRI is now free to add more routes through the station simply by programming the relays, without the need of any actual physical modifications in the track and signalling arrangements. The removal of this mechanical interlocking is also termed as Non-interlocking.