I noticed today that they've improved the passenger flow actually ON platforms 15 & 16 by removing all the seating, waiting shelters and drinks machines - not sure whether that's a temporary or more permanent measure though? Hard cheese if you want to sit down.
Permanent I think. In the planning drawings the platforms are completely bare of seating etc, but there may be room upstairs in the new H&C concourse.
P15/16 as drawn appears to have (working from east to west) 3 sets of 'normal' stairs spaced out along the platform, followed by a MIP lift, 'firefighter stairs', and lastly an emergency exit staircase at the far west end.
Paul