I'm relatively new to this area, but my understanding is that this line, or at least the northern few miles of it, were part of the original NP main to Tacoma. In any case, the tracks (probably with 70 lb rail at most) have been in place for years. Now they look (from the freeway) to be about 132 lb CWR with ballast that looks like what you see on Swiss railways...that is, each rock placed by hand.