At John Johnson’s workshop today we got a quick look at the progress now nearing completion for the entire span of the bridge. This also includes the last portion using wood bents now currently under construction. The exhibit as mentioned earlier in the planning phase represents a 1929 built Pratt Truss span wash-out in the early 1940’s with a line realignment. The newly added open plate girder and a constructed wood trestle complete the altered state of the river channel. John wrote this essay on the engineering rationale of the exhibit and its historical significance to the C&S line north of Westminster, CO as it winds its way north to Cheyenne, WY.
John Johnson writes:
Building a model or scene is easier for me if I have a story to tell. Our LT&N is an example how an idea was the foundation for a portable layout. The bridge project has it’s own story.
The Pratt truss was erected in 1929 (see portal) with wooden trestle across the flood plain. 1943 saw a disaterous flood wipe out the trestle and one abutment for the Pratt truss. War Emergency board authorized repairs but wartime restrictions dictated reuse of the Pratt truss. The track was re-aligned to avoid the “sink” where the abutment collapsed. A plate girder bridge was obtained on the used bridge market and was installed to help span the new riverbed. A short trestle completed the crossing. Manpower shortages precluded cleaning up the remaining original trestle as can be seen in the background.
Service was restored and the LT&N continued in it’s small way to help the war effort. Railroads made a big difference in the effort to supply troops and material for the war. Before the Interstates the highway system would have been hard pressed to move in a year what the railroads moved in a week.
More than just a model of a bridge, we have a little engineering and a history lesson in just 10′.
John pulls a lot of his research from actual railroad engineering standards manuals
We are building a branch line; however pre-1960’s would likely see a lighter 5 pile standard on the bents main line or branch line.