Coyote Creek Covered Bridge 37-20-02

The truss arrangement for the Coyote Creek Bridge is the same as the 1929 - Standard 60-foot Howe Truss from the Oregon Highway Department. However, the member designs are different and no cast iron connection blocks are used on the Coyote Creek structure.

The main difference between a Howe and a multiple king post from what I understand is that the tension members at the panel points in a multiple king post are timber, while the Howe has iron/steel members. This may be an over simplification, but that is the main point I have noticed.

I believe Will is by far the most knowledgeable on this subject since he actually spends a great deal of time rehabilitating and constructing the magnificent structures.

Not sure of the origin Will...I've heard that term since I was a teenager. I couldn't tell you any details as i haven't been there in forever.

It's my understanding that the Comstock Covered Bridge in Connecticut may also be a Howe single, although it appears that if it was it has been modified. This bridge was recently restored and also has a covered pony truss approach.

Interesting Tony - I'd not come across such a variant before, or the term. What is the derivation of the named type? Do we know who coined the term and when?

No close ups of the details to tell, are the Angle Blocks wooden or cast iron?

The WG calls it a Modified Howe, though it of course is not free from errors and omissions.

We have one of these in Indiana that is referred to as a "Howe Single".

http://bridgehunter.com/in/brown/bean-blossom/

A question worthy of asking, because it is a bit hard to categorize. The asking though, (in this instance at least) perhaps raises more questions than answers.

While many if not most Wooden patent trusses are liberally peppered with iron, including large Rods, and there were simple short span “King-Rod” trusses , I know of none to have been greater than two panels. No “MKP” variants seem to have had that name appended to them. This truss type always has wooden tensile elements which define the panel points.

That said, despite Coyote Creek everywhere being described as a Howe, it lacks a number of design details common to this truss type. Foremost among these are Counter Braces – While bridge engineers and builders have long discussed and even argued the need for their presence in panels towards the end of any given span, (while yes there is little reason for them in conveying loading in end or even second panels, as a builder I would argue that their presence is useful and necessary in both developing and maintaining camber) I know of no other named example which lacks Counters in the panels at mid-span. Doubled Braces are also absent in this truss, as are Angle Blocks / Shoes at the truss terminus – Always present in Howe's, in this instance the end panel Braces appear to be heeled into the Bottom Chord in a wood to wood joint.

Howe Truss panels which lack Counter Braces, can and do appear MKP like, they are none the less part of Howe type trusses...

The Coyote is however, in my opinion, not – It is a mongrel variant, more akin to a Modified Queen than a Howe.

Nelson does not seem to speak to it in his “A Century of ” - I am uncertain if Coyote Creek is like so many others, one of the State Highway Commissions standardized designs. Being part of Oregon's 20th Century wooden bridge legacy, somewhere in the record there is likely to be some sense of what its designer named it as being in Truss Type.

Why is this bridge (and others like it) considered a Howe Truss and not a Multiple Kingpost? Thanks.