Effect of T5? How soon do we reckon BA will start clamouring for preferential easterly ops?
Don't get me started on human factors!
From Heathrow Tower's point of view, it will have massive effects. At the same time as T5 opening, we're moving to the new tower, and with it a new system of data display (electronic instead of paper), and all sorts of other factors (different view of the airfield, different way of working, different way of co-ordinating with other positions in the tower).
Coping with all these new things at one time is going to be a HF nightmare.
Unless things are changed, our capacity as an airfield will decrease. to get around this, the idea is to have three ground controllers rather than two, but will we have the staff (both ATCO and Lighting Operator) to provide that? Interesting question. Of course, a lot of this new equipment and working practice is being driven by accountants and engineers, who with all due respect have little idea about ATC and how seemingly insignificant titbits of information from various sources enable an aerodrome ATCO to keep traffic moving in a busy scenario.
Even if things do improve, eveyone understands that the one thing that will suffer under the new procedures and equipment in the new tower is flexibility. Expect things to slow down.