One favorite, though the train crosses over the bridge at night in both directions, is the long bridge over Pend Oreille River (next to Lake Pend Oreille) in Sandpoint, Idaho. It is very long, single track, girder, and among beautiful mountain scenery.
Another favorite bridge, which crosses over the Sacramento River and a park, is the one at Redding, California. It, too, is very long, almost long enough for an entire freight train. Unfortunately, the Coast Starlight (in both directions) passes over the bridge at night, but you can follow the train as it curves around and look down at the river and the lights in the park.
Suisan Bay Bridge is also used by the Coast Starlight and the Capitol trains, and it is spectacular, high up, with views.
Here in Portland, there are four major bridges: The first Columbia River Bridge just south of the Vancouver Depot. It has a swing birdge section that opens up for river (boat, ship) traffic, Amtrak trains sometimes wait for it to be realigned for their crossings. While crossing (at least a mile long), you get views of both states (OR and WA), the river, river traffic, highway traffic on the highway Interstate Bridge, and Mt. Hood.
As trains enter Oregon from Washington, they come onto land on Hayden Island, the northernmost part of Portland, which as shopping centers and marinas and houseboats. It then crosses another bridge over another arm of the Columbia River onto the mainland. That bridge is also quite long and has a section that opens for boat traffic, though it doesn't seem to be used much any more, if at all.
A few minutes later, trains cross over the Willamette River on another major bridge. This bridge was originally a swing bridge, but in about 1990, it was replaced with a lift spand (to allow ships a wider passage through the bridge). It, too, is constantly being opened for ship traffic, and trains must wait for it sometimes.
Between Vancouver and Portland, the Coast Starlight, the Cascades trains, and the Empire Builder all use this route.
The other major bridge occurs almost directly after leaving Portland Union Station going east. The train crosses the Steel Bridge, so called because the original (1888) was the first all steel bridge over the Willamette. The present bridge (owned by the Union Pacific) opened in 1912. It has two decks. The upper level is for highway and light-rail traffic, while the lower deck is for railroad trains. There is also a parallel walkway for pedestrians and bicyclists. The bridge is of a telescope design: the lower level is raised inside the upper level for short boats and ships without affecting road traffic. For larger ones (such as the Navy fleet), the two bridges are raised together, which halts both road and rail traffic. The Coast Starlight and the Cascades trains to Eugene use this bridge. The Empire Builder uses the bridge for the wye capabilities to turn itself around for the next trip eastward. That can be an interesting process to watch.
River traffic on all these bridges obviously has priority over rail traffic.
