The trestle carries two sets of railroad tracks on ballast.
Eleven days has to be a world's record for building a quarter-mile-long bridge. Union Pacific must have had all the material in a nearby yard. Even so, they must have had three or four pile driving units working at the same time to have driven 200 piles in a week. Then there was less than a week to install the bent caps, place the precast superstructure, put down the ballast, and lay down a quarter mile of track. There must have been so many workers, that its amazing they didn't get in each others' way!
American River Bridges: Union Pacific Bridge (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.