In which Indian railway city has Indian Railways installed Asia’s largest Solid State Interlocking (SSI) signalling system?

Introduction / Context:
Solid State Interlocking, often abbreviated as SSI, is an advanced electronic signalling system used in railways to control the movement of trains safely through complex junctions and yards. Installing a large SSI system at a major railway location increases efficiency and safety by reducing the scope for human error and enabling more flexible routing. When Indian Railways commissioned Asia's largest SSI system, it attracted attention in current affairs, and exam questions commonly ask at which station or city this milestone occurred.

Given Data / Assumptions:

The question refers to Asia's largest Solid State Interlocking system installed by Indian Railways.
Options include Kolkata, Lucknow, Hyderabad and Kharagpur.
We assume that the reference is to a widely reported commissioning at a major junction on a busy route, and that the scale of the yard and number of routes justify the term largest.

Concept / Approach:
Kharagpur, located in West Bengal, is home to one of the longest railway platforms in the world and is a major junction of the South Eastern Railway. Because of its large yard and complex layout, it was chosen for the installation of a massive Solid State Interlocking system, which was described in news reports as the largest in Asia. Other cities listed in the options are important railway centres but were not associated with this particular superlative for SSI at the time referred to in the question.

Step-by-Step Solution:
Step 1: Recall that Kharagpur is a key railway junction handling heavy traffic between eastern, southern and central India. Step 2: Remember that Indian Railways news highlighted the commissioning of Asia's largest Solid State Interlocking system at Kharagpur, due to the large number of routes and points it needed to control. Step 3: Consider Kolkata, Lucknow and Hyderabad, which also have major stations, but are not cited in current affairs snippets as hosting this particular largest SSI installation. Step 4: Match this recollection with the options and recognise that Kharagpur is the correct city associated with Asia's largest SSI system. Step 5: Select Kharagpur and eliminate the other three options as not fitting the specific superlative described.

Verification / Alternative check:
Railway technology news and competitive exam notes mention that the Solid State Interlocking system at Kharagpur station was commissioned to manage an exceptionally complex yard layout, making it the largest of its kind in Asia. They also emphasise that this upgrade increases safety and allows for more efficient handling of train movements through the junction. No similar claim is made for Kolkata, Lucknow or Hyderabad in relation to SSI size, which confirms that Kharagpur is the station concerned.

Why Other Options Are Wrong:
Kolkata and Lucknow are important railway hubs and may have sophisticated signalling, but they were not highlighted as having Asia's largest Solid State Interlocking at the time of the widely reported commissioning. Hyderabad is also a significant urban centre with busy stations, yet it does not match the specific claim in question. Choosing any of these cities would therefore contradict the particular superlative used in the official and media reports.

Common Pitfalls:
Some students may be tempted to choose a large metro city like Kolkata or Hyderabad simply because they are more famous, without recalling the detailed news about Kharagpur's long platform and complex yard. Others may not be familiar with Kharagpur's importance beyond the presence of an engineering institute. To avoid such mistakes, aspirants should pay attention to details when reading railway related current affairs, especially when record breaking or largest in Asia type phrases appear.

Final Answer:
Asia's largest Solid State Interlocking system installed by Indian Railways is located at Kharagpur.