Actually, it is not impossible to extend PF 10 & 11 at CSMT to cater 24-26 coachers, but time is most important. They can't shut these down for weeks. Similarly it is possible to start and terminate a few trains from DR PF 5 (26 coach). May be these could only be possible with 5th & 6th lines between CLA & CSMT. First phase is CLA to Parel, that would make possible use of DR PF 5 as terminal for up to 3 trains. CSMT has been trying to develop Wadibunder yard to accommodate more trains for daily maintenance. There could be a couple of 2 new lanes available by next few months (if not weeks).