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michaelheggen.bsky.social
Michael Heggen 💯🐸 ❌👑
@michaelheggen.bsky.social
1K followers 390 following 1.2K posts
Farmer, forester, sawyer, builder, fencer, horseman, juggler, husband, mentor, tabletop gamer, feminist, Oregonian, LGBTQ+ ally, reader, lifelong learner, neuro-divergent nerd (no particular order).

Resident of Oregon's 6th Congressional district (OR-6).
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michaelheggen.bsky.social
🧵 How We Built Our Bridge, part 6

Link to Part 5:
bsky.app/profile/mich...

Here's a perspective view of the main span design, showing ten wooden arches tied together. Details in alt text.

For smaller versions, 2-4 arches are used. We needed more for our design weight.
High-angle perspective drawing of the main span with concrete abutments. There are ten wooden arches tied together to carry a design load of 10,000 lbs. Not shown is the 12-foot wide deck, the superstructure to support the deck, and the approach arches (which follow a similar 10-arch design). Each arch is built of 2x6 lumber, with a finished weight of roughly 650 lbs. per arch.
November 30, 2025 at 11:17 PM
michaelheggen.bsky.social
Today was brought to you by the following colors:

#SmallFarmLife #PNW
November 29, 2025 at 12:51 AM
michaelheggen.bsky.social
Barge board and knee braces installed at the east of the stable wing of the new barn. See alt text for details.

We had a small Douglas-fir come down near the sawmill a few weeks ago. The wood was still in good shape, so I bucked it into three 16-foot logs. (Cont’d)

#SmallFarmLife
The east end of our new barn under construction, with grey skies in the background. The walls are diagonally sheathed with 1x6 Douglas-fir boards. This part of the barn is a split level. The ground floor has three long, narrow window openings in the wall sheathing (why, yes, the window dimensions do indeed satisfy the Golden Ratio). That will be the feed room. The loft above has two openings: one being another long narrow window; the other one is larger to allow a pallet of feed to be loaded in. The larger opening will have a window in it to match the others. At the roofline, there are four evenly distributed knee braces made of Douglas-fir 4x4s. You can’t see if from the ground, but we did some joinery to ensure they do their job for a long time. :-) The knee braces are supporting a Douglas-fir 2x6 barge board that is 24 inches away from the wall. Deep eaves and rakes are vital for building longevity here in rainy western Oregon.
November 26, 2025 at 5:02 PM
michaelheggen.bsky.social
We compromised with a central arch height of about nine feet, as show in this detail.

This detail also satisfies Oregon Dept. of Forestry requirements that the bridge have at least three feet of clearance for a 50-year flood (see alt text).
Detail of central span, including stream profile. ODF specified that the projected flow of Pedee Creek during a 50-year flood would be 230 cubic feet per second. We needed to have at least three feet of clearance. But how high would the water be at 230 cfs? The are hydrologic models to calculate this, but I'm not a hydrologist. So I didn't have any idea how fast the water would be moving in a 50-year flood. Hmm. I went down to the creek and observed how fast the water was moving using leaves and sticks as a gauge. It was a bit less than one foot per second. That gave me a starting place. Water in a creekbed is subject to laminar flow—i.e. the friction of the creekbed itself slows the water down, but the farther away from the creekbed, the less friction. Again, hmm. I tried a seat-of-the pants idea: what if we just assumed than the water was only moving an average of one foot per second during a 50-year event? We just ignore laminar flow. From observation, I know that one foot per second is very slow for a raging torrent, so this is a conservative number. So, assuming one foot per second average velocity (again, this is conservative) means that we can use trial and error with either graph paper or modeling software to find a shape with one flat side (the water's surface) and the rest defined by the creek profile that has an area of 230 square feet. SketchUp is the modeling software I use. It took just a few tries to determine that a water depth of 6' 10" provided a cross-sectional area of 230 square feet. And Robert's your father's brother! We could show that no part of the bridge would be less than 37" above the water during a 50-year, 230 cfs event.
November 23, 2025 at 12:45 AM
michaelheggen.bsky.social
Side view of design, including stream profile. (Caption in alt text.)

The main span is 66' 8" with three smaller arches on each side for the approaches, each of which are just over 100 feet long. We limit the slope to 5% (5 feet of rise for 100 feet of run) to make moving loads easier on horses.
Side view of bridge design. The 66' 8" central span is a wooden arch with a wooden deck at a 5% grade. The approaches are each of three successively smaller wooden arches, covering just over 100 additional feet. This series of seven arches allows the entire deck to remain at 5% grade, which is suitable for horses pulling a heavy load. The connecting arches transfer some of the thrust forces from the central arch back to massive abutments at the ends of the approaches. We extended our creek survey over 100 feet back from each bank (same one-foot sample interval) so that we would have an accurate elevation model of the ground for the approaches.
November 23, 2025 at 12:45 AM
michaelheggen.bsky.social
This video was shot about 200 feet upstream of the crossing site, but it is typical of the creek bottom.

(We think the location in the video is where they got the aggregate for the concrete for the foundation of the farmhouse. Imagine digging yards and yards of this gravel by hand in the 1920s.)
November 23, 2025 at 12:45 AM
michaelheggen.bsky.social
🧵 How We Built Our Bridge, part 5

Link to Part 4:
bsky.app/profile/mich...

This image shows the result of our stream survey.
Caption in alt text

You don't need calculus to be able to see that this mild-mannered creek can become a raging monster.
Drawing showing the profile of Pedee Creek at the chosen site for the crossing, as surveyed on 11/3/21. Sample interval of 1 foot; sample length 72 feet. The creek that day was 20 feet wide and 20 inches deep at the deepest point. The ordinary high water mark was 8 feet, 2 inches above the deepest point. The width at the ordinary high water mark was 56 feet. The ground continued to gently slope up beyond the OHWM, with the west bank about a foot higher than the east bank.
November 23, 2025 at 12:45 AM
michaelheggen.bsky.social
Here’s our farm 21 years later in 1956 showing a bridge, but slightly downstream.

Hmm.

Caption in alt text.
1956 aerial photo of our farm courtesy of Polk County, Oregon. The bridge across the creek is more clearly visible, but it is now a few hundred feet south (downstream) of the 1935 photo.
November 16, 2025 at 9:50 PM
michaelheggen.bsky.social
The first thing in building a bridge is to figure out where to put it. Sometimes this is obvious—e.g. replacing an existing bridge—but we were starting from scratch.

Or were we?

Here’s our farm in 1935, and looked there! There’s a bridge!

See alt text for caption.
Our farm in 1935, courtesy of the Army Corps of Engineers and Polk County, Oregon. North is at the top of the image. Current property line in dark blue. Pedee Creek in cyan. Dirt road leading west from the barn in brown. For scale, the southern property line is just over half a mile long. The western property line is about 1/3 of a mile long. It’s hard to see, but there is a bridge over Pedee Creek. It was probably just logs with heavy planking spiked to them. Most of the west side of the farm had been logged recently. The stand of trees in the southwest corner are mostly old-growth oaks with a few Douglas-firs and grand firs and some big-leaf maple.
November 16, 2025 at 9:50 PM
michaelheggen.bsky.social
We had our first ursine bridge user last night!

He (?) did not pay the toll.

#SmallFarmLife #PNW
November 15, 2025 at 11:38 PM
michaelheggen.bsky.social
The view out my window one morning earlier this week. A good start to a day.

#SmallFarmLife #PNW

Caption in alt text
Looking west out the window of our 100-year-old farmhouse. The cherry tree on the right is at least a century old, too. There is a black Canadian horse grazing center, with a Clydesdale under the cherry tree. There are slightly frosty fields beyond the horses. In the distance is a line of deciduous trees near the creek. The brightest yellows are big-leaf maples. The tall yellows are black cottonwoods. The pale yellows are our beloved Oregon ash trees. There is mist rising from the creek and the Douglas-firs going up the ridge in the background. The mist appears to merge with puffy white clouds to the right. The sun is just illuminating the far side of the fields in our valley, with a blue sky above promising a beautiful day to come.
November 9, 2025 at 11:28 PM
michaelheggen.bsky.social
The interior walls of the stable wing on the barn are framed! The photo is looking west through stalls 2, 4, and 6. There is a doorway between each stall that will allow us to connect them for a mare and foal (or whatever).

A few more rafters to set, but roof is coming Soon™!

#SmallFarmLife
November 9, 2025 at 11:18 PM
michaelheggen.bsky.social
A good end to a rainy week here at the farm.

The lombardy poplar at left is named Fred, by the way. He has been in his full fall glory this week.

See alt text for details.

#SmallFarmLife #PNW
Wide-angle shot of our 100-year-old farmhouse (white horizontal siding with dark green trim) partially hidden by a holly bush. The sky is a pale blue with a few wispy clouds. Fred the lombardy poplar is behind the house. There is a century-plus aged apple tree at the right. Several horses are silhouetted in the middle distance, with fields beyond them. In the background is the ridge that forms one side of our valley, with the late evening sun casting a golden glow over everything.
November 8, 2025 at 12:13 AM
michaelheggen.bsky.social
And the day says farewell.

#SmallFarmLife
The sky looking southwest this evening, with the hills in silhouette and rosy clouds illuminated by the setting sun streaming off to the east.
November 3, 2025 at 1:07 AM
michaelheggen.bsky.social
What have you been doing to stay sane In These Times, you ask?

Well, the past two-and-a-half days we milled some Douglas-fir lumber to finish framing the interior walls of the stable wing of the barn.

Now it’s time to build stuff with it!

#Sawmill #SmallFarmLife
Our lumber trailer loaded with freshly milled 2x6 (for framing) and 1x6 (for wall sheathing). Longest boards are on the bottom at 18 feet. Shortest boards on top (8 feet).
October 29, 2025 at 9:30 PM
michaelheggen.bsky.social
The gable end walls of the stable wing of the barn are framed and we’ve started sheathing them.

Photos show the two ends of the stable wing. This coming week we will start setting the rafters in between them.

See alt text for the deets.

#SmallFarmLife
This is the east end of the stable wing of the barn. Ground floor is the feed room, with a feed loft above that will have a bathroom and feed storage. The bigger opening in the loft will allow us to load pallets of feed directly into the loft. This is the west end of the stable wing. There will be three airy spacious 20’ x 20’ horse stalls.
October 19, 2025 at 1:07 AM
michaelheggen.bsky.social
Better view of the orca/sperm whale. Hard to see, but followed by a One Piece flag.
October 18, 2025 at 10:15 PM
michaelheggen.bsky.social
I’ll see your frog suit and raise you…

#NoKings
October 18, 2025 at 9:37 PM
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#NoKings
October 18, 2025 at 8:49 PM
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#NoKings
October 18, 2025 at 8:44 PM
michaelheggen.bsky.social
Two unicorns and a polar bear are walking down the street, and the polar bear says…

#NoKings
October 18, 2025 at 8:39 PM
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#NoKings
October 18, 2025 at 8:23 PM
michaelheggen.bsky.social
#NoKings #Resist with all your might.
October 18, 2025 at 8:18 PM
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This orca eats fascists.

#NoKings
October 18, 2025 at 8:01 PM
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My arm isn’t long enough to show the crowd stretching off into the distance.

#NoKings
October 18, 2025 at 7:51 PM