The bridge that Track Fiddler showed us on the Weekend Photo Fun is very graceful. I was impressed that it was curved. Although his bridge is linearly bent, there are some curved truss bridges in Japan. They are all clunky and I don't know any modeled examples. I will show them for reference. (my blog post)
Added on July 21, 2020
Google Map: Nagasu bridge, Amagasaki, Osaka
Google Map: Yumenoshima bridge, Shinkiba, Tokyo
And Takara Tomy once released such a set on Plarail series.
Kuriu, KotaroKyoto, JAPAN
Interesting Kuriu and thanks for the compliment.
I've heard from a few civil engineers, building a curved railroad truss bridge it's next to Impossible because of the laws of physics and weight involved. Well I guess Japanese engineers did the next to Impossible then. I do see your pictures right here.
I noticed on your third picture, the long curved one. There are two spanning supports over the first roadway, one between the first and second roadway, one between the second and third roadway and one in the water way. But the bridge is still curved between the supports and also the bridges in your first and second picture.
Fascinating!
My brother is going to model an S curve girder plate bridge. I advised him to put a tangent bridge between the two and he did. These curved girder plate bridges are made by Kato.
TF
You can do an indeterminate curved truss; it will just weigh more and not be as strong for the mass as the 'straight' equivalent. And you will have to deal with different effects of live load on the supports, which might actually come into tension...
Here's the picture that used to be an S curve bridge with a tangent bridge in between. I see my bro must have changed things. He must have moved the landing over to get rid of the second curved bridge.
He sure is getting good at painting that foam to look like rocks. He didn't carve the foam, that's just the way it was when he installed it with some Alex Plus caulk in between chunks. I may have to go over there for a foam painting lesson.
The Kato curved bridge. Not my cup of tea. My brother only had to use one to get himself out of a snag. A line will be going under it. You know what? ... He's getting more done than I am.
A common way to install truss bridge on curved track is to widen it as straight truss. Wait a while about the Girder Bridge.
Google Map: The Nagara bridge of Hankyu Railway, Osaka (my blog post)
[July 17, 2020]
Google Map: Osaka-Umeda, Hankyu Railway (my blog post)
A good example of how curved track is put on girder bridges can be seen in some of the overhead views of the Amtrak 501 Talgo wreck in Dupont. The very largest radius that would fit was squeezed in to get the least speed restriction -- unfortunately still far, far too much for the nonsense signal conventions used there.
Of course, the girder bridge in curved track is straight and wide. This is common sense, but many modelers don't know it. Let's study at "Bridge and Trestle Handbook" by Paul Mallery (my blog post).
Google Map: The 6th Misakubo River bridge, JR-Tokai, Shizuoka (my blog post)
Google Map: MomoyamaGoryoMae (Kinki-Nippon Railway). Kyoto
[July 21, 2020] Added 3 thru girder bridges of Keihan Railway, all in Kyoto (my blog post).
This has 3 spans.
However, there are exceptions in the world. I know two examples of through girder bridge (My blog post).
Google Map: Manseibashi (JR-East), Tokyo, built in 1928
Next is Portland, Oregon, where I was taught on Trainorders.com. There may be others if you look for it.
Google Map: Portland OR
Track fiddler. My brother only had to use one to get himself out of a snag.
We are better off to do something impossible, impractical, or umprototypical to get us out of a snag rather than to build a layout that we will not be happy with.
If using a curved girder bridge will make a feature I want possible, I will do it.
-Kevin
Living the dream.
This rail combination bridge crosses the Fraser River near Vancourver, British Columbia. It isn't discernible, and the light doesn't help in this photo unfortunately, but the closest truss is actually pie slice-shaped. It affords a broad wye coming off the single truss in the distance, branching left and right to continue in either direction on the north littoral of the Fraser.
SeeYou190 If using a curved girder bridge will make a feature I want possible, I will do it.
By the way, I would like to introduce you to a strange set of bridge girders in Japan. It looks like there is no vertical curve at the connection. The passing speed was 10 mph. Photos were taken in 2011. I think that this should not be done by modeling as well as prototype. (my blog post)
Google Map: Awagasaki, Kanazawa (Hokuriku Railway)
Interesting
I see it but I don't get it Kuriu. Some kind of forced down by the wheel thing? What are they for? And those black railroad ties with the circle on the end are kind of curious. Never seen those before. What are those made of? I noticed only some of the ties but not all. Perhaps Replacements with a steel ring to keep the ties from splitting?
Track fiddlerI didn't know my GPS navigation would go all the way to Japan until now. I was looking through all the linked pictures. Your Homeland is beautiful.
My middle daughter is quite the globe-trotter. At least once a year she and her husband spend a couple of weeks outside the country.
She has said that Japan is the most beautiful country they have ever visited.
Track Fiddler, "vertical curve"? Please search the net for the needs in actual railways. The point is to improve riding comfort. If this is improper, it will give the passenger a fluffy or kneeling feeling. As you all know in models, it is to prevent the coupler from releasing and the cow catcher from hitting the rail. It is said that steam locomotives with many wheels cause slip and that the fuel tanks of deisels rub against the rail. See "Easing the tops and bottoms of grades," page 73-81 of MR Nov. 1974 issue.
Black ties (sleepers) are composite material made of fiber reinforced plastic. Search the net for the "composite tie" benefits. Those are manufactured by Sekisui Chemical Co. in Japan. I think the steel rings are, as you say, to anti-split. Can you understand my poor English?
Arched viaduct is a major concern in curved track, beyond truss and girder bridges.
What happened was the cover of the July 1989 issue of the Japanese magazine "Hobby of Model Railroading" (TMS). Masashi Ohno, the author of this N-scale layout, wrote, "The side of the arch bridge should be flat, but then the width of the bridge will be wide. I curved the sides." Therefore many of us Japanese fans did not doubt it. For example, the Landwasser Viaduct in Rhätische Bahn (Wikipedia), Switzerland. However, the Glenfinnan Viaduct (Wikipedia) used in the Harry Potter movie appeared to have curved sides (my blog post). The curved sides were found one after another. The following is a Japanese example. Which is more common in the United States?
Google Map: Goshin Line (unfinished in 1959), Wakayama (my blog post)
There is a tremendous difference between engineering curved trusses/long-span arches and making curved viaducts.
Of the latter there are many examples, the most immediately famous being the Thomas Viaduct on the B&O. Stone bridges built to follow curves are not far behind. See the thread Brian (railandsail) started a couple of months ago about using stone-faced arches for this sort of construction.
Key is that each arch is relatively short-span, and in particular will not have trouble with peak load on the 'outside' radius inducing tension forces in the arch springing or other parts of the (indeterminate, mortared) deck. This will be true of concrete-arch construction with or without stressed deck.
It is easy to take a long elliptical-arch concrete structure and think that you can just curve the free span of the arch the way you'd curve a viaduct -- the problem is that without additional structure, you can't. Compare Maillart's structure for the Salginatobel bridge (which is a structurally-elegant three-hinged arch) with the Schwandbach bridge of about the same period, which is substantially different in important ways. (Bear in mind that there is a very sharp curve at one end of the Salginatobel bridge.)
Very impressive image of your layout Kuriu. I see you have nothing lacking in your craftsmanship abilities
Outstanding!
You should join us in the Weekend Photo Fun thread
P.S. Your knowledge of Bridges continues to be quite interesting. Don't hesitate to share more.
SeeYou190 Track fiddler I didn't know my GPS navigation would go all the way to Japan until now. I was looking through all the linked pictures. Your Homeland is beautiful. My middle daughter is quite the globe-trotter. At least once a year she and her husband spend a couple of weeks outside the country. She has said that Japan is the most beautiful country they have ever visited. -Kevin
Track fiddler I didn't know my GPS navigation would go all the way to Japan until now. I was looking through all the linked pictures. Your Homeland is beautiful.
You got that straight Kevin.
My oldest daughter spent four years in China teaching English. She went across the short strip of ocean that separates China and Japan to visit there as well.
The pictures she sent me on some of her excursions there were breathtaking. My phone recently ate all my pictures. When I see her today I'm going to have her send them again so I can post some.
I am surprised. Noone has mentioned Keddie wye. 2 curved approachs in mirror images to one track and numerous bridge types
Also the PRR high line in Philly has a curved masonry two track arched bridge befor Zoo tower.
This is the pie-shaped truss at the north end of the CN Fraser River Bridge that I mentioned earlier. Found the image by googling, and it was taken by Andy Cassidy. Not my photo.
Go back to the original photos:
Individual truss spans are NOT curved, they are each straight themselves.
The bridges are composed of straight spans, each rotated slightly, to follow the chord across the curve, that give the APPEARANCE of being curved.
The trusses themselves are not curved. They follow the series of chords along the curve. There is a BIG difference in structural analysis--and constructability--although curved girders can be designed and fabricated, the myriad of different members of a truss does NOT lend itself to horizontal curvature within any one span.
Yes, individual spans can taper or widen out as needed to accommodate a special situation like a curve onto a bridge, but the actual truss members themselves are NOT curved.
All truss designs are inherently rigid by nature. Attempting to introduce curvature into a truss would result in additional stresses on the structure that would vastly complicate the design and would lead to structural instability--ie risk of failure.
The bending in more than one direction or about more than one axis is what would lead to problems. Some things can actually be designed, but also not easily fabricated in real life.
Although curved girder bridges are possible, they are practically avoided and are only used in the real world where absolutely necessary. In some photos above, it is clear that straight girders were used, and the width of deck adjusted to allow for curvature. In a couple other situations, it does appear that horizontally curved girders were actually used.
In America, many modelers are modeling some time "many" years ago. Curved girder bridges are built TODAY but would not have been at all common when steam locomotives ran...
John