A SIX-PEDESTRIAN treadmill has been added to Cambridge University's wobbly bridge simulator, built by department of engineering staff in response to problems on London's Millennium bridge.
Structural engineering lecturer Allan McRobie said he launched the project after his wife and children described the wild ride they had experienced on the crossing's opening day.
'I had to miss the opening, but from what I heard there was obviously a serious problem, ' McRobie explained.
He went straight into his workshop and built the test bed largely out of scaffold tubing and planking for 'virtually nothing - apart from a £20 Vauxhall Astra shock absorber and some springs from the local DIY store'.
Adding a standard one-person treadmill compensated for the short length of the platform, and allowed initial observations of human response to lateral movement to be made.
McRobie said the platform's damping ratio could be adjusted from zero up to 50% of critical.
The larger treadmill, which was constructed last week, would, he added, allow more realistic simulations of crowd behaviour.
Representatives from Millennium bridge designer Ove Arup have already inspected the simulator. Departmental head Professor David Newland has been appointed as an advisor by client the London Millennium Bridge Trust - but there has so far been no outside funding for McRobie's work.
Imperial College researchers have begun trials with their swaying footbridge simulator, it was confirmed this week.
Tight security surrounds the intensive research programme, which is intended to produce hard data on pedestrian inputs for Millennium Bridge designer Ove Arup. Informed sources suggest that Imperial has fitted sensors to the deck to measure the loads from volunteers attempting to balance themselves against induced sway.