Here’s a little nugget tuck away in the cranium for those inclined to transit-related trivia: The largest metro rail system in the world now belongs to Shanghai thanks to yet another new line opening. Check out this fascinating post at The Transport Politic. Excerpt:

Now Shanghai offers 282 stations and 420 km (261 mi) of lines, compared to 408 km in London and 368 km in New York, which now have the world’s second and third-largest rapid transit networks. Unlike those cities, which have only minor line extensions planned, Shanghai’s expansion plans are only half complete: not only does the city have 140 km of more lines currently under construction and intended for service by 2012, but it has an additional 300 km planned to be ready for operations by 2020, by which time this city alone will have more rapid transit mileage than the entire country of Japan.

By the way, all this was built in the past 15 years. The tab by 2015 is expected to reach about $150 billion; The Transport Politic points out that in the U.S. the federal government is spending about $2 billion a year to help metro areas build transit lines. Shanghai, on the other hand, is making what appears to the be the most significant investment in mass transit in human history, writes the blog.

For the record, the Metro rail system reached about 79 miles with the opening last year of the Gold Line Eastside Extension. And, of course, there is more on the way. The 8.6-mile Expo Line from downtown to Culver City is under construction and officials are planning to break ground this summer on the 11-mile Foothill Extension of the Gold Line between Pasadena and Azusa.