# On18 Trestle – Pt IV

 Math I know there are those out there who will run screaming in horror at the mention of “Math” – so I will keep that to this one page and you can jump past it – in horror or otherwise revulsion. 🙂 – to go directly to Pt V please click this link
 What I have to work with The trestle stretches across the gap with a 20″ length – or 80′ full-size. From The right-side abutment (AR) to bent B4 it is straight. From B4 though, it curves in approximately a 11″ radius. Since a curved trestle is made up of lengths of straight stringers I ended up five segments – Segment 1(AL/B1); Segment 2(B1/B2); Segment 3(B2/B3); Segment 4(B3/B4) and Segment 5(B4/AR). Segments 1-4 or each about 3″ long, with Segment 5 7″ in length. Bent B5 is located at the center of Segment 5 just to keep in step with the other bent spacing. This then gave me two problems. Since the radius of the trestle set the where the segments joined I ended up with a bent over the track at B3 .. and at the edge of the cliff at B5. The question then is .. how to resolve that.
 Spanning I know already. Someone is going to point out that “Gee Ed. Just use a metal bridge”. Ummmm. No. I am using wood. That means that I need to span between B2 and B4 and support the section joint at B3 (about 6″ or 24′ full-size). I also need to span between B4 and AR – and support the theoretical joint at B5. The supported section there is not that entire length .. an intermediate bent about where the blue tape is between B5 and AR makes sense but that will still leave a span of around 5″ or 20′ full-size.