The Walnut lane bridge was certainly most of my wanting to reproduce something similar in HO scale. Although the Walnut lane bridge is a roadway bridge with cantilevered sidewalks, the main structural elements for a railroad bridge would be similar, and I did not try to reproduce an exact copy this bridge, which is right in my neighborhood.
Walnut Lane bridge from creek walking path
The bridge was built in 1908 and at that time was the longest masonry arch span in the world, just now finishing a restoration.
The Museum of Science and Industry has a model train display that is really much more than just a train layout. It is about transportation, and how the railroads move goods from place to place.
The fact that it is beautifully crafted, with scale large sections of Chicago and Seattle and the industries , plains, mountains etc in between, makes it a modelers must see if you are in Chicago.
The buildings in Chicago are true to the sections of the city that is being modeled. Two times an hour there is a short night segment to show the display in that setting.
Of course along the way showing double stack containers, mountain bridges and peaks, not to mention some human interest in a stream
UP in the mountains
Finally ending up in downtown Seattle including the docks.