On the efficiency of transit

"Transit is the most space efficient mode, and thus it should be rewarded with dedicated ROW rather than tossed into low-efficiency auto traffic" - Warren G. Wells

I hate to be the naysayer, but that's kind of irrelevant. In terms of moving people, what matters isn't space efficiency, but time-efficiency. Transit moves a lot of people per vehicle, but not a lot of people per lane. For urban traffic, the main capacity limitation are at intersections. But even there, for a dedicated transit line to be  more space-efficient than an automobile, you basically have to have 90 people on the bus, and a bus coming every 5 minutes (which is pretty high quality BRT).

The space-efficiency of transit simply isn't relevant from a transportation efficiency perspective. But the advantage of transit is enormous in terms of space efficiency, simply due to parking**. Each parking spot requires between 250-400 SF, and each car requires about 8 parking spots. So every person on the bus saves about 2500 SF of space. 10 people on bus saves half an acre of parking. 2000 people by bus saves 100 acres of parking. 

So when we talk about the efficiencies of transit, we're really talking about the space efficiency of urban land. (For pre-war transit, supplying transit transformed rural land into urban land, with the concomitant increase in rents. We need to forget about that--it was tied to a specific non-recurring historic context). For modern transit, transit in the 'light rail' era, the purpose of transit is to reduce parking demand, not transportation demand. (Transit reduces transportation demand only by forcing people to accept a crappier version of transportation, reducing their consumption of it, ie- people drinking eating fewer vegetables because the only ones they can get are rotten). 

So if we're planning fixed guide-way transit, it's all about the parking garages. Because that shows two things: a) there is a lot of transportation demand there, and the costs associated with providing parking are already high, and b) there is some (agency, corporation, muni) with the capacity and need for capital intensive transportation infrastructure. Those are where the stations need to go. Other places will get transit service, but only by virtue of being on the way.

Why b) is important: If transit efficiency is all about reducing parking demand. As a society, we've more or less made the decision that capacity improvements benefit everyone (they don't), so we're ok with government provision of roads. But we're much charier of provision of parking, because we associate parking with private land uses (never mind that it's hand-in-glove with automobility). So when we start providing rapid transit, we're really reducing parking demand at a handful of places. And those places tend to be: colleges, hospital, and civic centers. Because those are the places we've perceive as being part of the 'public' realm, and local/regional voters are willing to help those, in a civic-sense. State buildings/campuses often fall under the same penumbra, as do Federal buildings--the Feds provide half of the capital funding for new transit, and they understand the financial value of reduced parking demand.

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*A bus without dedicated guide way isn't BRT, regardless of FTA's bullshit terminology. 

**Traffic engineers don't care about parking. They aren't trained for it. They only care insofar: a) access to and from it doesn't disrupt roadway capacity, and b) there is enough of it that cars don't back up onto the roads.