Here is a look at some of the transportation headlines gathered by us and the Metro Library. The full list of headlines is posted on the Library’s Headlines blog, which you can also access via email subscription or RSS feed.

Manhattan, as seen in this 2005 photo. Photo by Jens Karlsson, via Flickr creative commons.

How many people can Manhattan hold? (New York Times)

Great story that attempts to find a very evasive answer to a big question: just how many people can Manhattan hold? Excerpt:

As much as determining Manhattan’s maximum capacity is about the art and science of urban planning, the question is in some sense much more about psychology. Given all the tradeoffs and rewards of living in this staggeringly complex, gloriously maddening city, there is no final accounting or projection. When it makes sense for our lives, we make do with less space. Like most things that are a matter of compromise and desire, it comes down to another simple question: Just how badly do you want what you want?

Manhattan’s current population of about 1.6 million is about 700,000 fewer people than lived on the island in 1910. The population, of course, more than doubles on weekdays with commuters going to work and other destinations. One expert is quoted saying that the transit system is running at capacity during the day in Manhattan and that transit needs to be expanded or trains need to be run closer together.

I’ve heard occasional talk over the years from people — mostly not-in-my-backyarders — that L.A.’s population needs to be capped. That’s crazy talk, of course, because the population density in many parts of the metro area is pretty thin compared to other metro areas around the world. When people talk like this, they pretend they’re talking about people but they really mean cars.

Baldwin Avenue to go under rail tracks (Pasadena Star News)

As part of the Alameda Corridor East project (ACE), Baldwin Avenue in El Monte will be placed in an underpass beneath busy freight and Metrolink tracks. The project just received a chunk of state funding last month. The ACE project aims to build 20 new grade separations in the San Gabriel Valley and improve safety at many others — resulting in more safety for cars and trains.

Personal car sharing comes to L.A. (L.A. Times)

A firm allows motorists to rent their cars to others by the hour or the day. The car owner and firm divvy up the rental fees, which begin at a reasonable $5 per hour. Neat idea — we’ll see if it sticks.