Photo by Craig Philpott
This appears to be a three-hinged arch with latticed arch ribs. I have a arch design text book by Conde McCullough that has examples of common arch arrangements. In this book McCullough shows an arrangement similar to this one. The example shows lenticular shaped rib segments, but this one is quite similar.
I have attached the page showing some of the typical arch arrangements as presented by McCullough.
I hope this helps out.
View attachment #1 (PDF document, version 1.4, 102114 bytes)
OK friends, what we have here is an arch, a wooden arch, pre 1920. What kind of arch is this? This bridge was located on a primary road into the redwood logging country of Northern California. The exact route and bridge location is now used by Hwy 101.