How should we value an individual transit station? Proximity to jobs and housing is of course important, but even important is how the addition of that station increases the value of the network as a whole.
When University Link opens in 2016, it will be great for people who live and work in Capitol Hill and the UW. At the same time, neighborhoods along Central Link (Downtown, SoDo, Beacon Hill, Rainier Valley), will instantly have access to two significant new destinations. Property values surrounding Central Link stations will likely increase substantially, even though actually nothing’s “changed” in those neighborhoods. It’s as if you woke up one day and Comcast had doubled the speed of your internet connection.
This is roughly the principle behind Metcalfe’s Law. Metcalfe proposed that the value of a network was roughly proportional to the square of the number of nodes. If five people have telephones, then the network has a certain value. If 10 people have phones, the value of the network quadruples, rather than doubles. It’s why Facebook and Twitter — with their hundreds of millions of users — are so valuable.*
To take the analogy back to transit; if you have a station near your neighborhood, then the value of that station increases exponentially as stations are added elsewhere throughout the city. When light rail goes from the initial 13 stops to the planned 33, the value of the network will be roughly 644% greater than it is now due to all the new origin-destination pairs that will open up.
Of course, Metcalfe’s law assumes the value of each station is equal. In reality, that’s rarely true. On social networks, some users contribute more than others. The same will be true of Link stations. A freeway station in North Seattle may be attractive to the people who live nearby, but probably not a frequent destination for people who live in, say, Overlake. By contrast, a station right in the heart of Capitol Hill or Bellevue or the Airport has the potential to be valuable to everyone on the network.
This is why it’s so important for every station to maximize the development opportunity around it, and why even people who don’t live in the neighborhood ought to be able to weigh in on the development of the area around a planned station. A botched walkshed doesn’t just affect the neighborhood that surrounds it, rather it degrades — substantially, quadratically — the value of the network as a whole.
* Some have challenged Metcalfe’s equation with respect to very large networks, but the man himself is sticking with the law for smaller numbers like our transit example.