Arup carried out an extensive test programme to provide information that would enable a solution to the phenomenon to be designed.

• Further modal testing of the bridge was carried out following closure which indicated the validity of the original design assumptions and modelling.
  
  
• International experts in the fields of bridges and vibrations were commissioned to provide additional advice.
  
  
• A database of suspected occurrences of the same phenomenon was compiled from literature and news searches.
  
  
• A programme of laboratory tests on moving platforms was carried out at the University of Southampton and at Imperial College to determine pedestrian forces and the influence of lateral movements on these.

Based on the results of these laboratory investigations, Arup decided that the only way to properly replicate the precise conditions of walking on the Millennium Bridge was to carry out crowd tests on the bridge deck itself.

The first test with 100 people in July 2000 was used to devise a load model for the dynamic forces created by us when we walk. To do this the bridge was instrumented to measure movements and a proportion of the crowd was fitted with heel sensors to measure the precise timing of their steps.

In December 2000 a second test with 275 people was used to load test a prototype installation of the proposed solution. The test confirmed the loading model developed from the research conducted by Arup. Extracts of the testing can be seen in the video footage and further details are given in the Results section.