The Sam Hill Memorial Bridge is only a half-mile long. A number of the bridges on the Pacific Coast Route are longer. The most oft-discussed bridge there is the Coos Bay Bridge, which is over a mile long.
People do talk about the Coos Bay Bridge, but I think the Pacific Coast bridge people fear most is the Astoria-Megler Bridge, which is a whopping
four miles long! The fear of this bridge has people going far out of the way to avoid it. (I'm pretty sure that's the reason why ACA's Pacific Coast Route through Washington is so weird.) I've ridden it several times, and didn't find it anywhere near as bad as people made it out to be. I think the length is what gets people worked up--no matter how fast you ride, you are going to spend at least fifteen minutes of your life on this bridge, and once on, there's no way out until the other end.
One good thing about the Astoria bridge is there are traffic lights at both ends, controlling the flow of vehicles onto the bridge. Traffic comes in waves vs. being a steady flow. So there will be a minute or two with no cars passing, then a minute or two of cars passing.
Getting back to the Sam Hill Bridge, there is a light on the south side of the bridge, so if you are northbound you'll have that same "waves of cars" phenomenon like the Astoria Bridge.