THE CLASS 1 RAILROADS of North Amer- ica still own and maintain miles of old timber trestles that are in dire need of replacement. Since the trestles are typically located at sites that can only be accessed by rail, these bridges have to be replaced using rail-mounted, locomotive cranes. Further, revenue service dictates very short windows for the bridge crews to access the site, remove the old bridge, install the new bridge and return it

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