Jhansi To karera distance is 40kms.. if its taken from datia it will be 65km. plus If jhansi-Sawai madhopur track is made it will be beneficial for Up, Bihar traffic to meet Rajasthan. so it's better to connect it from jhansi not from datia because twice Rake reversal won't suit much.
Jhansi Sawai Madhopur track can be joint close to jhansi A cabin so that Kanpur origin traffic can halt jhansi and go towards sawai madhopur without having a rake reversal.
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more... Plus Datia has massive forest land in the west so building a track by cutting forest is not a good idea.