Recent difficulties with the high-tech bridge crossing of the Thames in London caused it to "sway" on being opened to the public last month.
The recent difficulties with the high-tech bridge crossing of the Thames in London, which "swayed" alarmingly on being opened to the public last month, have been the cause of embarrassment to the leading engineers and architects from Ove Arup responsible for its construction. Recent reports on the design process featured the engineers' original design concepts scribbled on a bar napkin-almost a caricature of engineering mythology. However, the ability to draw on the back of an envelope and get somewhere close to the final design is an important but fast disappearing skill amongst engineers. This disappearance is accelerated by two contrasting effects: first, the increased reliance on computational methods and "packages," and a reduction in the mathematics content of engineering courses to make them more attractive in a management-oriented society. There is a need to understand the basic interactions involved and also to recognize when approximations give an acceptable answer. The corollary to the latter point is an understanding of the cost of taking the solution beyond the limits of accurate knowledge of the variables involved. Thus, knowing when to stop is as important as recognizing when an answer is close enough.
These issues were brought to mind recently by two disconnected events. The first was my attendance at a Pressure Surge Conference in the Hague, where I presented a keynote paper on "Unsteady Flows in Building Services Utility Systems," and the second was clearing my office for a paint job to be undertaken while I am away from the University in August.