Arthur Newton's mischievous tribute to the architectural profession over its contribution to the Millennium bridge (NCE 16 November) reminded me of my days as a student at UMIST in the 1950s, when we were made to evaluate the loads in structural bracing and design accordingly - a precaution apparently overlooked in this bridge It also made me wonder what more perceived and proven wisdom of the past might be relevant to our present-day problems and my mind turned to the increased number of broken rails, which I understand to affect continuous welded rails only.
Former railway engineers like myself will recall fatigue cracking in the Comet airliner in the sixties, which prompted the discovery that bridge girder stiffeners were vulnerable too.
Measures had to be taken such as terminating stiffener welds above the bottom flange.
The days of the bullhead rail in 60ft lengths is effectively past, but might it be that the stressing and prevention of linear expansion in continuously welded rail is causing the stresses and cracks about which the experts know so little?
There may be no evidence, to coin a phrase, but is that because no-one has looked for it?
J D Mortimer (M), 21 Green Drive, Clitheroe, BB7 2BB.