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Dan, I presume you are building your bridge on a ninety degree angle. If you are building it on a skew, then we have alot to talk about. First, I would just put a piece of wood there and come back in and install the bridge later. Just set the wood in there loose and you can pull up the track and the wood block and install your bridge anytime. Next, I'm a little fuzzy about your comment that the bridge is not long enough. Are you using the 50 ft span(s)? Is it long enough. How long is the gap you are crossing? Can you use as many piers as you want or do you need the clearance under the bridge? Abutments: I am building my own for the skewed bridge beacuse nobody makes anything like this. I bought some Scale Crete and it works great for making concrete substructure (Piers and Abutments). Just make the shape you want out of wood and then coat it with Scale Crete. An abutment has two elements always, a backwall and a seat. The backwall would normally be about one foot to eighteen inches thick to retain the fill just behind the bearings. It goes from the seat to the subgrade of the track and is usually twice as wide as the track. The seat is where the bearings rest. The seat should be from two foot six inches to four feet wide, as wide as the girders plus four feet and at least two feet deep. If the seat is shallow like this then it is referred to by some as a shelf abutment, the smallest you will see. If the abutment is taller then the seat will extend all the way to the ground. This is the type of abutment you usually see advertised and is something like thirty feet high. I think Chooch makes a nice one (a cut stone and another type) but now that I have my Scale Crete I can make my own for real cheap. Most abutments also have wingwalls to retain the fill beyond the seat area. The site conditions and some personal preference will dictate how these are laid out in plan. Some engineers like to extend them on the same line as the backwall, others like to flare them back away from the opening under the bridge. If you think scour is likely, then I would flare them back and place rip-rap (like talus) around the base of the wingwalls. Let me know some more about your intentions(sp?) and I will see if I can help further. Good Luck - Ed
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