I have been doing research on the Hanging Bridge in Royal Gorge and have found some discrepancies in the length of sections. The "official" length of the bridge is 175 feet according to several sources including Bridgebuilder.com. There is also a fairly detailed drawing of the bridge in the Transactions of the American Society of Civil Engineers, Volume 26, May 1892. The pages for the drawings are around pages 525 to 527 I believe. In these drawings it is shown that the bridge was built in three sections with the following dimensions:
Eastern Section: 94 ftMiddle Section: 91 ftWestern Section: 88 ft
This gives a total length of 273 feet for the bridge.
Clearly the 175 feet in Bridgebuilder.com is referencing something else. In the drawings it can clearly be seen that the eastern and middle section of the bridge are supported on the north side by anchors in the clif face, with the south side of the bridge supported by the arches over the bridge. The arches attach at the west ends of the eastern and middle sections. The eastern end of the western section is also supported by the arches, but only about 10 feet of the western section is supported by the cliff face. There was a concrete piling supporting the eastern end of a free standing portion of the bridge. The ASCE drawings show both an elevation view and a plan view of the bridge next to each other and drawn to the same scale. In the drawings the length of the unsupporte part of the western section is 98.5 feet. If you subtract 98.5 feet from 273 feet, you get 174.5 feet which is remarkably similar to the "official" length of the bridge. Unfortunately, since the western section is a total of 88 feet long in the drawings, this is impossible. The unsupported section is about 10 feet less than the total length of the section, so I submit that the unsupported section is actually only 78 feet long.
I believe that the "official" measurement came from these drawings, ignoring the discrepancy in the length of the western section. So the "official" length is the length of the bridge that is supported on the north side by the cliff and the south side by the arches. I measured the bridge in google earth a couple of weeks ago before I found these drawings and found it was about 275 feet long. This was very confusing because it appeared that google earth was waaaay off on the dimensions. I now believe google earth to be correct.
There have been three other threads discussing the bridge dimensions: http://cs.trains.com/mrr/f/13/t/189141.aspxhttp://cs.trains.com/TRCCS/forums/p/133103/1495187.aspx#1495187 The third thread is earlier and I don't have a link, but it was posted by Electrolove, where he references drawings and the lengths of the sections.
I was wondering if anyone has noted these discrepancies and explained them, or been to the bridge and actually measure the lengths of the sections?
Been down to the bridge, but didn't take my tape measure...
Trying to recall if I participated in any of those earlier discussions here. What I'm pretty sure explains the seeming discrepancies, though, is that the bridge has been rebuilt over the years. It's not the same bridge, although substantial parts of it were reused, which gives the impression, along with the unique "hanging" segment, that it is the same.
I'd accept the differing measurements as all essentially accurate for how it was when it was measured. Depending on the era you model, then take the stats that are closest to the year that works for you.
Mike Lehman
Urbana, IL
I am planning to model it as originally built, as much as possible. I doubt if the length has changed any, regardless of the other changes made.
Keep in mind that your best source of online info is the Rio Grande group on Yahoo. IIRC, that where I'm remembering hearing about the changes in reported length being due to reconstruction. I think you can search the archives for old messages without being a member, but it's worth signing up for as a long time member IMO.
The bridge sits in the bottom of a canyon, where flood waters can take out or damage abutments, etc. This also makes anything more than end views difficult, although there are a few pics that have enough angle to see the spans.
Robert L. LaMassena, Rio Grande...to the Pacific!, has the earliest pic I'm aware of on page 287, when it was under construction by the P&AV, the Santa Fe subsidiary that lost the "war" to the Rio Grande. So it wasn't built by the D&RG, for starts. The index has a few more small pics listed under "Royal Gorge."
Better pics in Jackson C. Thode, George L. Beam and the D&RG, from the first couple of decades of the 20th century, when it was still three-rail until the early 1920s IIRC. A pic on page 121 shows damaged track from a derailment, another potential cause for rebuilding than the river itself.
If you're going to stick it down in a canyon like the original, leep in mind that getting a view of it will be similar the difficulties found in photographing the real thing. Choose the length that works for you to the best of your knowledge. No one is going to be able to call you out about any differences, because they are not at all obvious given the retsricted camera angles available to document it over the years.
I noticed there was a Bridgehunter.com entry also, with 7 pics:
http://bridgehunter.com/co/fremont/hanging/
It calls for a 175' overall length.
Yes, I think I mentioned that in my original post. Clearly the entire bridge is 273'.