Joy of learning, power of simple observation.

We are surrounded by myriad of things. There are two types of people; some wonder why things are the way they are, some other people don't pay attention to or do not even recognize. I am strongly of the former type.

Here's an example. New York city subway routes are mixed-labeled, using both numbers and alphabets. Have you wondered why? Have you given a second of thought about the mixed labeling scheme, instead of just focusing on the routes you need to take? Also, not all letters are used; letters A through F are used, G through I absent, J through N used except for K, etc. Furthermore, route color code makes the map farther from being intuitive or sequential. If you were to design a labeling scheme, the most natural way would be using A to Z sequentially, or grouping sequential letters with the same color. You can consider double digit numeric codes, or abbreviation representing a region (like NYC bus routes M48 / Q70 / Bx33 for instance). NYC subway employs none of those obvious labeling system. In fact I haven't really wondered the reason either for years until recently, although I was aware of the mixed labeling scheme itself as most of people would (maybe not?).

One simplistic answer is because NYC subway has more than 26 routes. Alphabet alone can't cover the entire routes. But the real reason has much more complicated historical background. Today the NYC subway is operated by a single authority - MTA (Metropolitan Transportation Authority). But in the past a number of private companies operated parts of the subway system with their own routes nomenclature. For efficient operation after operator consolidation, the routes were re-labeled into a more systematic set. In short, IRT(Interborough Rapid Transit)-operated routes bear numbers in present, and the routes by other two major operators have alphabet labels. (read this Wikipedia article for detailed evolution history) Interesting?

More often than not, a mere curiosity into small easy-to-neglect detail reveal a surprising wealth of story behind the scene and time. The joy of learning, the power of persistent desire to know.