So Seattle’s set to start running a new light rail service. Scott Guttierez has a writeup of it in the PI. That’s good news, I guess. Although with only a single rail line running through a city with over 3 million people in it, Seattle was badly underserved by rail before this new line out to Tukwila and it’ll still be badly underserved now.

Guttierez’s report actually gives a nice little illustration of how a city can end up with such crappy mass transit infrastructure. First, in the waning days of Grunge, Seattle voters rejected a new rail transit plan. A year later, in 1996, they accepted a plan that invested a little more than half as much money in their city’s transit infrastructure. That was a plan to build a 21-mile light rail line from the U district to SeaTac. But then there were some cost overruns and the plan got hacked to a 14-mile line with another 3 miles to come.

Imagine what the US’s interstate system would look like if, whenever any one part of it was going to be a little overbudget, they decided to save that money by making the road shorter.