How Do They Do It?

Monday 11 October, 7:30pm on Five

This factual series lifts the lid on the incredible engineering behind everyday life. Presenter Robert Llewellyn is on a quest to understand the extraordinary engines, machines and structures that form the backbone of 21st-century living. This week, Robert examines how an American freeway handles a quarter of a million cars a day, and explores the process of printing cash. Chicago’s Dan Ryan Expressway is one of the busiest roads in the world. Every day, it is used by over 300,000 vehicles -more than twice as many as it was originally built to handle. There are seven accidents on an average day, making a total of 2,000 per year. In order to keep the traffic moving, the Illinois Department of Transportation has just invested almost a billion dollars to strengthen, widen and improve safety on this essential road. The main problem faced by the department was that the old highway was just 69cm thick. To cope with modern traffic, it needed to be 111cm thick – but building on top of the old road was not an option owing to the clearance required beneath the freeway bridges. Therefore, the entire road had to be removed – lane by lane – at a rate of 3,000 tonnes per day. This rubble was then crushed and reused as the foundations of the new road. So much new material was needed to complete the expressway that a factory was constructed next to the road, ensuring that the concrete never stopped pouring. Every year, the US Mint produces up to 20 billion coins – the equivalent of 60 for every American. Each new coin to be issued is the culmination of a complex design and engineering process. In December 2005, Congress approved the creation of a series of dollar coins featuring the US presidents. The process of making these new bucks begins with the designers at the US Mint in Philadelphia. Working in clay and plaster, they produce a detailed relief portrait 12 times larger than the coin. A transfer engraving machine then copies all the fine details of the relief onto a master hub, from which the dies – steel plates used to strike an image onto a coin – are made.

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