The sweetest sounds in the universe - "chai chai"

खड़कपुर(in length)
मुगलसराई, कल्याण (in frequency of trains)

The platform of Kharagpur Railway Station is the longest railway platform in India. The length of the Kharagpur Railway platform is 1072.5m. The platform was originally 716m long. It's length was extended twice, once to 833m and then to its present length. Excluding subway platforms (the Chicago subway has the longest one), Kharagpur has the longest railway platform in the world. Kharagpur is located in the Midnapore West district of the state of West Bengal. It is famous as the place where the first Indian Institute of Technology was established. Kharagpur also has one of the biggest railway workshops in India.

KALYAN JN has 8 platforms....4 for suburban and 4 for MAIL/EXP trains......MAIL/EXP platforms are also utilised by suburban locals but not vice versa......also you have suburban trains (LOCALS) arriving and departing at a frequency of 3 mins......which means that there are close to 1200 suburban train services in both directions (CSTM-KYN and beyond KYN) Very complicated tracks......goods divison is different which has around 6 platforms.......connected to almost all the major cities/towns in the country........

CNB came out only for Mail/Express, if u considering blog discussion input by me!!
If u add Mail/Exp/Local/Freight, then Kalyan is undisputedly the busiest Junction, handling maximum train count...
Mughalarai is the biggest Junction/Yard & quite famous, as no train can pass it, without stopping Technically!!