The universal reaction among architects to events surrounding the inauguration of the Millennium Bridge during the past week has been the hope that Ove Arup can pull off the phenomenally difficult task of evolving a damping system capable of self-adjusting to live loads varying from several thousand users to none at all.
This task is, of course, made harder by the fact that the key ingredient in the problem, namely the crowds whose presence has highlighted the greater-than-anticipated movement, can't be present during the experimentation process.
If Arup does manage to solve the problem of excessive sway then the success of the bridge will, as Lord Foster has implied, be almost entirely that of the engineering team.
What no-one appears to have done in recent days is to question the premise behind the design strategy for the bridge; this is in large measure due to one of the great skills of Lord Foster's office, that of 'making the weather' in terms of getting the chosen solution to appear the inevitable one.
Since the 'blade of light' tag first hit the media a couple of years ago it has seemed to me that the chosen emphasis represents a lost opportunity. The whole point of a pedestrian bridge crossing the Thames adjacent to St Paul's and free from the immediate presence of exhaust fumes, foul-mouthed cyclists lacking headlights and the most rudimentary knowledge of the highway code, not to mention the risk to life itself of white van man, is what it represents: a place to dawdle, stop, take in the astonishing views, rendezvous, maybe even picnic - all without blocking the paths of other users.
This indicates the need for considerable, and possibly varying, width as well as balustrading designed to impart the maximum possible degree of shelter from the gustiness of most river crossings.
The emphasis on speed and light in the rationalising of the built Millennium Bridge appears curiously irrelevant to these factors, and the inevitability of some degree of noticeable deflection that is inherent in the nature of its design will tend to discourage all the above activities.
There is also the psychology of perceived safety: as the Forth Rail Bridge demonstrated in far more challenging waters, providing reassurance to the would-be user does not need to imply a Ministry of Transport stodginess of design. In this particular location one can imagine two bridges - one on the axis of St Paul's and one on that of Tate Modern - meeting on an elongated island, probably nearer the south bank than the north. The aesthetic of that island could be a matter of choice: maybe 'look-no-hands' minimal or possibly robust enough to support a colony of trees and flora, seats and even a cafe.
Such a bridge would be as much a place to look from as look at, but it would still generate its own sense of magic. Furthermore, it would achieve this while avoiding what might be termed the Leaning Tower of Pisa syndrome, namely the nagging sense that what you are coming to see may well have vanished without trace the next time you come to make that journey.
Jeff Kahane, London EC1