27th November

8am
As the team set up for the days filming, Adam appears out of the Science Shack. Has he been working through the night on solutions to the bridge wobble or was he taking a sneaky coffee break whilst the rest of the team were hard at work?

9am
Nine year old Alex Gocke talks to Adam about his experience of being on the Millennium Bridge when it wobbled. Alex crossed on the second day the bridge was open with his Dad. He describes how the bridge wobbled and you had to walk in a funny way to get across. He also remembers having to queue for the bridge to get across, not because it was too crowded but because they were limiting the amount of people on the bridge because of the wobble.

Alex is the first to have a go on our Millennium Bridge Simulator, he shows us what happens if you try to walk normally across the bridge and wobbles rather quickly across to the other side. Luckily Alex developed a slightly more controlled way of getting across the real Millennium Bridge or he might have ended up in the Thames!

As Alex demonstrates, to get across a wobbling bridge you have to waddle rather than walk, putting your weight from one side to another. This kind of walk accentuates the rhythmic stepping the team looked at yesterday. If other people on the bridge were walking like this, could the stepping have added to the wobble?

10am
Ian Fletcher from Epsom also talked about his experience of the bridge. He was one of the first people across in the afternoon and felt rather unnerved by the experience. “I felt like we would all end up in the river!” A few days before, Ian had joked to his friends that he wanted to cross it when it opened as he didn’t reckon it would stay up long!

Ian has a go on our simulator and talks to Alan about whether we’ve got our wobble right. As none of the team were there on the days the Millennium Bridge wobbled, Ian’s input is very interesting. Although we’ve got the basic movement right, he remembers the movement being more like a roll on a ship and there being an element of vertical movement too. The Science Shack team are left to puzzle this out and conclude that some of this extra movement may be caused by the amount of people on the bridge compared to ours. A thousand extra people on our bridge may create the same effect, but there wouldn’t be much space for walking!

11am
The Millennium Bridge Simulator swings from side to side as the Science Shack team attempts to walk up and down it in a straight line. It is impossible to avoid walking both in step with each other and in step with the sideways movement – exaggerating the effect.

12pm
Allan McRobie works at Cambridge University. He is an engineer who specialises, among other things, in ‘bridge dynamics’. He designed our simulator and by putting exercise treadmills on our scaffolding bridge gets it to simulate the movement of a very long bridge. Allan has tremendous enthusiasm for bridges in general and the Millennium Bridge in particular. He loves the fact that ‘the biology took over from the nuts and bolts’ when it was first used. He explains that when it was first tested the bridge began to work like a biological system as opposed to an engineered one. ‘There was more flesh and blood on the bridge than concrete and steel’, he says.

‘The Millennium Bridge is a slender, daring bridge – so its dynamics come to the fore. We like to describe most engineered systems with simple laws so we can do the maths – but many things are ‘non-linear’ especially biological systems. Non-linear means you get a disproportionate change resulting from an input. Rio Ferdinand the Leeds United player’, he adds, ‘cost eighteen million quid – so did this bridge’. We can safely say which one Allan thinks is truly worth the money!

2pm
Joan Lasenby, a lecturer at Trinity College and expert at capturing motion digitally, helps Science Shack understand the subtle ways people walk and the forces involved in varying kinds of gait. She attaches fairy lights to volunteer Pete and tracks them using three cameras hooked up in a very clever way to her computer. Hollywood animators use exactly the same technique, but their machinery can cost millions. Joan and her colleagues have developed a more basic (and affordable) system that is helping medics understand a range of diseases related to movement. Because she has fewer cameras than Hollywood she has to ‘help’ the computer by ‘pre-installing’ into the computer’s memory information about the way a skeleton controls and restricts movement. This helps the computer calculate what is happening faster (and ultimately cheaper!)

4pm
Pete, a volunteer who came out to help us yesterday and was immediately exploited to the maximum by Jem, models the Science Shack high tech solution for fixing Allan’s Millennium Bridge Simulator – a half dozen Astra car suspension units. Will they stand up to the harsh test we have waiting for them?

5pm
The local pearly King and Queen arrive to cut the ribbon and declare our – newly fixed - scaffolding bridge open. It is hard to stop them breaking into song at a moment’s notice.

As the Pearly Kings and Queens sing ‘Roll Out The Barrel’ our dancing girls start strutting their stuff on the scaffolding bridge and do their damnedest to make it swing. But Science Shack technology defeats them and the bridge is declared officially viable.

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Content last updated: 29/09/2005

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