One of our admins, Tejas to be precise, asked me the rationale behind numbering of platforms 9A and 9B at Sealdah Station. However as I was not aware of the reason, I visited Sealdah Station this afternoon to investigate the matter.
Historically, Sealdah Station, consisted of 3 parts viz. Sealdah North, Sealdah Main and Sealdah South, with 6, 3 and 5 platforms respectively, making up a total of 14. However, with increasing pressure of more and more trains being introduced, both suburban EMU locals as well as non-suburban passenger and M/E trains, there was a felt need to augment the number of platforms. Accordingly, about 10 to 15 years ago, platform no. 9 was closed for rail traffic and with added space...
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generated by partially demolishing the adjacent goods shed, 2 new platforms were constructed. However, in order not to disturb the running sequence of numbering of platforms 10 to 14, the 2 new platforms were numbered as 9A and 9B.
Additionally, in the Sealdah South Sections, 2 new platforms are being built on either side of the existing 5 and work is almost complete. While the one alongside platform 14 has been numbered PF 15, the one alongside 10 has been numbered as 10A, for the reason already explained.
Thus, the station now has a total of 17 platforms, from 1 to 15 (including 9A) apart from 9B and10A. Although the distinctions between the wings North, Main and South have now become blurred, the North Wing (PFs 1 to 6) caters to Suburban local EMU services to the districts of Hooghly, Burdwan, Nadia and 24 Parganas (North). The Main Wing (PFs 7,8,9A and 9B) accommodates the non-EMU services comprising passenger trains (eg. Lalgola Passenger) as well as Mail/Express trains (eg. Sealdah Rajdhani Exp). The South Wing ( PFs 10A AND 10 TO 15) is used by suburban EMU local trains heading to various destinations in the district of 24 Parganas (South) as well as the few odd EMU trains plying to stations on the Circular Rail Route like BBD Bagh and one service to Kolkata Terminal.
Interestingly, the structure of the station is rather unique and L-shaped. PFs 1 to 9B are aligned along the vertical arm of the L, whereas PFs 10 to 15 including 10A of the South Wing are aligned along the horizontal arm of the L, with a separate terminal building, which is interconnected with the North/Main Sections.