Speed is one aspect of lhb but it also had a lot of other good facilities like enhanced seating capacity..crash worthy design, less sound producing wheels , pnumentic disk brakes, jerkless coaches, which in case of icf is no where ..
Otherwise why rb is keen to replace icf with lhb.
All because of advantages..
A old lhb coach whose maintainence is due is...
more... equivalent to a new icf coach..
Also lhb requires less maintenance than icf.