I am someone who frequently asks the question "Why?" about the design of everyday objects, because of the interplay between design and operational research. On my way to the office today, I noticed that one of the advanced stop lines for cyclists seemed much larger than others that I encounter. So I asked myself "Why is it that size?" and then speculated about the optimal size for such a road marking.
The wonders of Google led me to a website from the UK Department for Transport, which says that the "cycle reservoir should be between 4m and 5m in depth. If the reservoir is shallower than this cyclists can feel intimidated by the close proximity of the vehicles queuing behind them. If the reservoir is deeper than this, motorists may feel encouraged to encroach into it." So the design is based on psychology, which links to some of my earlier blogs here. It is reassuring that someone has thought about the design and suggested guideline measurements.
So if you see me around Exeter with a 4metre tape measure, you will know that I am checking the roads!