Hi,
Hidden away in the TFG Administration Forum is a post by Will Truax where he provides a link to a scholarly study done on covered bridges that can be downloaded for free from Federal Highways in Adobe.pdf -
http://www.tfhrc.gov/structur/pubs/04098/04098.pdfThis is an 8mb file containing 346 pages of photos, charts, diagrams and discussion on the design, engineering and construction of Covered Bridges.
This freebee download is essential reading for anyone engaged in the field of timber framing and I would recommend that this should be added to the various download links provided on the TFG homepage since it contains significant and important materials concerning the use of timber in construction.
Major contributions have been made by Dr. Ben Brungraber and many other timber framing noteworthies too extensive to list here.
I am impressed.
Regards
Ken Hume