11 car trains on the 7 line

[kmothersil]

I'm not sure I asked this question, but could someone tell me how come the 7 line runs 11 car trains while the other IRT liners run 10? Aren't most of the platforms on the IND,BMT,and IRT 600 feet long? Is there something I missed as to why the 7 is the one that runs 11 car trains?

 

[BStyles]

Check www.nycsubway.org there should be a reason behind the 11-car mystery.