Our trains are fast because it took us forever to build a light rail system.
Our trains are fast because we were slow to build a light rail system. Charles Mudede

For Zach Shaner of Seattle Transit Blog, the slow development of our light rail line has a good side. When you move at our turtle-like pace, you can see the future better, make smarter decisions, and cut fewer corners. Portland, on the other hand, moved hare-fast to construct MAX but, in the process, made mistakes that have resulted in a system that's significantly slower and less efficient than ours. (Nevertheless, Portland has nearly 100 miles of track, and we have less than 20—so, we are nowhere near being anything like "all that.")

The main reason for MAX's situation is much of it is an at-grade system, while most ours is elevated or underground. (When ST3 is completed in 2023, most of Link will be elevated.) One consequence of this mix, which has much to do with our hilly geography and a lack of an extensive railway legacy, is capacity. Link can run four cars at a time; MAX cannot (the small blocks of Portland, which are great for pedestrians, present a constraint for its trains). Also, Link's trains are much faster and have a higher frequency, with trains running every 6 minutes at rush hour and 10 at normal times. (Shaner provides an excellent technical explanation for these features.)

All in all, the reason why our system is becoming what it is is certainly accidental. For one, our slowness was not the result of deep thinking and planning. We were and still are so slow coming along because that's how we have been socially conditioned—cars fast; public transportation slow. I do not think it is time that's of value here but the cost of the thing—and a cost that has its cause in the accident of our geography. We are forced to put a lot of money into this project, and this is where the real difference is being made. Shaner says as much: "(Seattle and L.A.) are building high-quality, frequent, grade-separated transit in the contemporary United States, and both have the price tags to prove it."