Unlike Brian, I think the $1 billion number is probably right. I’ll give a few reasons why.
The Sonoma-Marin comparison is not apt at all, since that train goes through rural areas, and has relatively few crossings. There are scores of crossings for that BNSF corridor, some of them in the downtowns of major employment and residential areas, and the track crosses major arterials. There’s even a “double crossing” at Totem Lake, and it runs in the middle of the street in Renton.
There are two huge bridges that would need to be re-built for the BNSF corridor, the Wilburton tunnel and the Wilburton tressle. The Wilburton tressle is a 975-foot-long bridge over a ravine in South Bellevue, and is not in good enough shape to carry large passenger trains. The Wilburton tunnel was a bridge over I-405 where the BNSF tracks were. The Tunnel was removed. Building 1000-foot long bridges or bridges over major interstates is very expensive.
Those are just two major reasons. The track and the track bed are in terrible shape. New right-of-way would need to be acquired to building passing sides, and to connect the disjoint pieces of the track in Woodinville. Stations are expensive, and so on.
But really, who cares? $1 billion or even $500 million for 5,600 or so riders? Forget it! McClellan station will get more than that many next year. There are more spending options than there is money, and 5,600 riders doesn’t justify the expense.