I was interested to learn from the article on the Millennium bridge that the lateral sway problem may be a human behaviour phenomenon rather than a structural problem.
If this is the case should not human behaviour be investigated for a solution as well as structural engineering?
This led me to thinking of other situations when people walk in step and the answer of course is when they are marching to music. If in different sections of the bridge marching or rhythmical music was played out of phase with adjacent sections people would tend to walk in time with the music in their section and thus not all in step at once.
Loudspeakers could be placed in the handrails. The music need not be played continuously but switched on automatically when say 1,000 or 1,500 people are on the bridge.
Such a solution if it worked should be considerably cheaper than £5M.
David Williams (M), email@example.com