I think building a proper tier the full width of the north stand would be extremely problematic, not least due to the fact that the roof slopes from one end to the other... they'd also have to remove the control room - and where would the big screen go?
Anyone who went to Anfield last year will know how uncomfortable it can be!
I wonder how many extra seats could be squeezed in this way? If you could fit 2.5 seats for every 2 it would increase our capacity by a quarter - to 38,500.
I heard that extra seats could be accommodated by lowering the pitch and either making it smaller or reducing the gap between the pitch and the stands. Would cost a fortune though and would probably only add a couple of thousand seats at most.