When you go on a journey, you begin by finding yourself a long way from your destination. However, as you move on the destination becomes closer and perhaps clearer- it can focus in from a town to a street, to a house, even to a room in the house.
I thought the same thing would happen with engineering design. That is, if I wanted to check out something such as how to calculate horizontal radius, I would find myself zooming in to one specific formula or set of values – and that would be it. In fact the opposite happens – the more I looked into horizontal radius, the more detailed and extensive became the information and the competing options. For example, I thought horizontal radius was a function of speed, friction and superelevation. But
- Speed depends also on vehicle type
- Friction depends on tyre condition, which depends on tyre pressure
- Superelevation even depends on the dominant type of weather
- and there are also “hidden”features such as “cost” and “factor of safety”.
In an earlier post on superelevation( here) I identified 17 features which affect superelevation, so maybe there are as many as 40 features which affect horizontal radius (say 3 * 17 less 11 to allow for duplication).
Maybe a new design approach would begin by listing the features which can influence / or be influenced by a geometric design parameter. For example, for horizontal radius these might include: