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Feeling a bit under the weather and starting writing this post at 8 PM (really 8:40), way later than I had intended, but I will press on regardless.

Many cities have already embraced transit, in the form of urban rail (which I use to refer to variously streetcars, light rail, and "heavy rail" or subways, also "rapid transit", with the ideas to be presented referring primarily to the latter two), even if not always as a way to counter climate change, but more as a way to chase down economic development and, it sometimes seems, to add a gimmick or tourist attraction to their cities. Just this year there's a veritable boatload of transit plans on various local ballots. Portland's heavy investment in transit and other anti-sprawl policies have earned the envy of cities as large as Los Angeles. And Portland is a mid-size city at best, though with its spiffy streetcar and other urban rail systems that could change.

As I outlined in my previous post, mass transit has a ton of many and varied benefits, but it takes some care. Think of two residential neighborhoods in your community far enough apart to be distinct, but close enough to be almost adjacent, not "on the way" to Downtown, and with none or few amenities for people from outside of either neighborhood to visit. If you built a transit line just connecting those two neighborhoods, who would use it? What reason would people in one neighborhood have for visiting someone in the other? Tourists might want to use it but how would they get there from the places that are actually interesting? The problem only expands as we extend it to other uninteresting neighborhoods.

So you can't just plop down a transit line anywhere you want and expect to reap the benefits. If anything, transit-oriented development actually poses a problem in such circumstances: companies looking to build office buildings will see the transit line that skips past downtown and build somewhere near it to advertise the easy connection to people along the line. As I said before, there is not really a relationship between where people live and where they work; people will work where they are most suited to, and live where they can and want to. There are still people who will need to use their cars to get to those jobs. So if jobs are placed anywhere other than downtown, that exacerbates traffic caused by people going every which way to try and get to their jobs.

For this reason, if any first transit line is going to make a dent in global warming and resource use, as well as make a dent in traffic, it needs to at least go and preferably terminate downtown. One transit line alone, of course, is really only serving the communities along that line, so even just within the city the job is not done yet, requiring the addition of more lines, and those can't just go wherever you want them to go but should serve downtown as well. That takes time, and it could require the voters to approve expansions several times, as due to modern financial, political, and practical considerations, it's rare that a transportation system can be approved more than 5-10 miles or so at a time. A full-fledged system can take 20 years or more to develop, but it's worth the effort even if it might be too late to make a dent in climate change, for reasons elaborated on in my last post. It's worth inquiring if a proposed transportation plan is intended to be part of an eventual larger system, and how that line fits into that system, in addition to its value in the here and now.

Following those principles, we can expect the system to eventually take on a hub-and-spoke form, with several branches shooting out of the center. Obviously there are people who will want to go places other than downtown and they might not want to be shafted with having to go downtown to go places that might be less than a mile away on another spoke, and so we might want to create routes that bypass downtown in some way, but not a lot - Chicago's rail system, for one, is highly centralized on downtown. More concerning, there are land uses rare enough other than work that transit might be the best solution for simple trips to them; airports and sports stadiums are the obvious examples here. Ideally, downtowns can be the equivalent of shopping malls so they can be out. As the system grows and matures, it's possible downtown won't be able to support any more jobs, and some transit service would then need to be provided to alternative job centers.

I'll expand on these principles, especially on a macro level, and examine some theoretical and practical applications, in later posts.