It looks fantastic, but........ Would a bridge this thinly made actually have carried the weight of a steam locomotive or even that of a diesel locomotive of today! Looking at photos of Pratt Truss Bridges I see alot of MEAT in the Steel, this etched bridge lacks alot of that MEAT. Someone please help me out here. Am I the only one that questions the thickness of this bridges Steel Supports? Beams, braces, columns! I am not counting rivots, I am just looking at the prototypical aspects of it! Other than this, it looks fantastic! Tim
I went to an NMRA clinic on bridge design, and it was all explained. A bridge consists of compression and tension parts. The tension parts are thin and lacy, and the compression parts only have to resist compression in one axis. So, I went to Z Scale Monster and took a look, and I think the bridge looks fantastic, and reasonable for the components. -Robert
I thought the Micron bridge was a 1800's design, weren't they all light and stringy back then? I do wish his bridge was a little bit more modern, but my layout has trackwork done so it's of no matter to me. I can just see everybody running their modern equipment on these.
More Modern Version! Me Too! I figure all of these old stringy bridges have been replaced by now with more modern versions. Then again, almost everything Micron sells is late 1800 - early 1900 stuff! Just a thought. Hobo Tim
Guys... look no further than Google. Check out this site: http://www.preservationhowardcounty.org/ELGuilfordPratt.htm The Pratt Truss Bridge shown below was built in 1902 for the B&O. Though no longer in use, it still stands today. This road served a granite quary so weight was an issue. Now here is something really interesting... Pratt truss railroad cars! This was found on the following site: http://railroad.union.rpi.edu/rolling-stock/Flats/95-2-Well-hole-Flats.php Rob
Hi Hobo Tim, There are many Pratt Tuss bridges in use on our country's mainlines today. If you come to Southern California and drive along the coast going South from LA to San Diego you will see one on the Ex Santa Fe line just before you leave Camp Pendelton. All freight trains and Amtrak use it to get into San Diego. Metrolink uses it to get between Oceanside and L.A. for the daily commute. I bet that there must be one still in use somewhere close to where you live. For old spindly bridges look at: http://en.wikipedia.org/wiki/Brooklyn_bridge The Brooklyn Bridge. Opened for use on May 24,1883. At one time it carried subway trains also. Still in everyday use for walking people, cars, busses and trucks and it is sold to some unsuspecting oaf at least one a year. I almost bought it but the guy wouldn't take my check written on the Bank of the Mississippi River. Held up by wires! Over salt water! 123 years old and still going strong.
I am not questioning whether they still exist on railroads today, I am just stating the Micron's bridge looks a bit anorexic! Thin! Un-stable! Rib's are show'n! Archaic! Of primitive origin! Not worthy of holding up today's modern railroad forces! If I had a large layout/module of early steam era I'd find a way to buy 2-3 of them and incorporate them in a mass river crossing, but I don't and I won't! Damned if I want my modern "Z" scale looking like this! This may not be a Pratt Truss Bridge, but it is still archaic! I praise Reynaurd for his achievements, but only wish he would have made it meatier, or a bit more modern in appearances! Yes, their are newer looking modern Pratt Truss Bridges. Just my opinion again! Hobo Tim p.s. No need for any other justifications! I am wrong and all of you guyZ are right!
Tim, there is nothing wrong with that bridge. Just imagine the crowd it would bring in a show. All those trains falling into the gorge would be a crowd pleaser.
Spndly Bridges I can't find the LINK, although I have the photo on my system of another view of this bridge , but take a look at this one which is The Freeport Bridge in Texas. http://www.railpictures.net/viewphoto.php?id=34880 This appears to be very light, yet from an engineering standpoint is pretty strong. One of the things that have to be considered in bridge design is WIND. The Tacoma Narrows Bridge was blown down by wind causing the bridge to oscillate in a manner that the oscillations finally brought the bridge down. For a while after that bridges were designed with THIN members so they wouldn't catch the wind.
224' Span! Don, The photo of that bridge in Texas has to be about 150' span! It appears to have somewhat of a beefy frame. Reynards bridge is 224' span! Big difference! That is All I am saying, no more on this subject! I look forward in seeing the shorter length bridge he has in the making! Hobo Tim
