Ok, this is for the world famous tunnel builder ,,Duncan. Who we all know was killed in a tunnel cavein at the edge of the town ,Duncan. My bridges are NOT to scale, they are made in proportion to photos with engines sitting on them or to catch the "feel" of a bridge built in an era. All latest bridges are Mini 8" wide inside to inside. That way if used, Garden metal Model cat walks can be used and it will clear most 1:20th scale locos. And mini 10.5" high (off the rail head)to clear gunderson double stacks and most steam engine stacks. those are the basic. the first 30" bridge is made appr 8" on center vertical supports
next bridge was layed out 9" on center to meet the span and brake evenly with the W style supports.
The MLS canyon bridge was also 9" O.C. to brake evenly. 3/4" Sq tubing is used as the largest size either wood or steel. 1/2" is all the rest.
The Bangs Canyon Bridge is 30" high and layed out on 12" O.C. the arch is drawn out on a table before final sizes are determaned. lengths does not matter, because the longer the bridge the greater each spacing to keep in proportion.
this double track bridge is layed out 8" O.C. thus it is alittle over 5'. It is about 18" high and note the cross bracing, again keeping the mini clearance always. hope these tips help. Keep in mind principles of building, not exact copies. I have been rebuilding some of mine simply cause I was able to use a welder and I think the catwalks help finish off the bridges making them more believable.
Um, just to clarify a certain misconception, I did NOT completely die in a cave in, however, I think I may have lost a glove in the cement mixer...
Thanks so much for going to the trouble of capturing the dimensions!!! I was looking for confirmation of my preliminary proportioning. It looks like I was pretty close, but it always helps to have my work "checked" before I commit the resources...
Roger on the "adjustment" of proportions in order to capture the "feel". Some of my earlier sketches and plans just didn't look "right", so I tweaked the spacing and/or material dimension selection. This also became the point at which I thought I'd seek your help. The pictures have confirmed my earlier corrections.
For general reference, the thread on your steel roadbed, which also contains the general construction of the Bangs Bridge comes to a current total of 58 pages when printed out. I've started a series of notebooks for shop reference, which should come in very handy during the fabrication phase.
Ralph was also suitably stoked after reviewing the notebook. Time to order some steel...
Thanks again, Marty!! I'll get a lot of use out of the info you've posted up, and I believe that quite a few others will, too!!!
Marty, those bridges are nothing short of amazing! I like the idea of working from a photo, and sizing to 'look right'. That's a good way to go. SandyR
Marty's post is very interesting. I spend a lot more time on eBay than on mylargescale.com. I am beginning to notice obviously out-of-scale bridges being offered. Some I like, most I don't. Most are not intended to be whimsical.