The bents are located about five feet apart at the centerline. Since I had a clear area
to work in, I used a string from the center to swing an arc to each bent to mark the
centerline. I then worked out from the center line of each bent to position the
stringers. A 16 foot length of lumber made three stringers for a curve or covered 15
feet of straight trestle. I used a lapped joint between stringers that allowed me to
fasten both stringers to the top beam of the bent with one bolt. This also provided a
pivot point for the curve. These lapped joints were heavily caulked to retard water
infiltration. All treated wood cut ends of the bridge and trestle were brushed with
preservative. Flat washers are used with all bolts and nuts. I used standard nylon
lock hex nuts on the trestle. The decking was made from used cedar 2x4s and
fastened with deck screws . I set them with a 1 ½ inch spacing on the straight while
on the curve I pinched the inside spacing and expanded the outside spacing when
necessary but only at the pivot points. I adjusted the position slightly to keep the bolt
heads exposed below them. This will provide access to the bolt heads for tightening.
The only ones that I can not tighten are the hidden ones in the bottom bent beams.
One reason for using the cedar is the warning on the treated wood that says that it
should not come in direct contact with aluminum.
|North Pacific Coast Railroad
|Bridge and Trestle Construction
|Click on photo to enlarge.
|This material is provided for personal use only - all rights reserved. 2007