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Posted June 16, 2019, by Everett Watterson (Evwatterson6 [at] gmail [dot] com)

Yes, the bridge was there when I visited yesterday, albeit with some minor sagging when heavy trucks crossed it.

Posted June 16, 2019, by Daniel

Bridge History

The existing Snake Lake (Gopher Hill) bridge was built in 1938 was originally used as the Rock Creek bridge before being moved to its present location in the mid 70's after the Rock Creek bridge was replaced with present concrete structure.

Existing Bridge Information

Snake Lake Bridge over Spanish Creek is a single-lane, clear span steel pony truss with high abutment walls comprised of precast concrete panels with tieback anchors and was constructed in 1969.

that's what the replacement page states, interesting that they don't have an exact year for relocation.

Posted June 16, 2019, by Tony Dillon (spansaver [at] hotmail [dot] com)

Quite possibly a relocation date.

Posted June 16, 2019, by Daniel

I'll add that I was surprised to see that it was riveted. How many bridges were riveted that late?

Posted June 15, 2019, by Tony Dillon (spansaver [at] hotmail [dot] com)

With the decent ratings and low ADT maybe they realized how stupid it would be to waste money to replace it!

Posted June 15, 2019, by Daniel

As of today the bridge is still there with no signs of construction etc. Not denying that it may be doomed.

Posted June 12, 2019, by Luke

Unfortunately that doesn't appear to be the case.

Posted June 12, 2019, by Erik Hoffman (norcalroadswebsite [at] gmail [dot] com)

Okay, I see now. Sorry, I scrolled through too fast and thought the pictures of the approaches were main spans.

Posted June 11, 2019, by Erik Hoffman (norcalroadswebsite [at] gmail [dot] com)

The bridge still exists and the demolition project page has been taken down, so I'm hoping perhaps that project has been dropped.

Posted June 11, 2019, by Daniel

I agree. Photos also show that at least one end has a straight road for a significant distance, which isn't the case at this location.

Posted June 8, 2019, by Catherine Wieder (cgwieder [at] wieder-law [dot] com)

This bridge is being replaced. Traffic delays June 2019.

Posted June 5, 2019, by Erik Hoffman (norcalroadswebsite [at] gmail [dot] com)

Found what appears to be a twin of this bridge downstream on Bull Creek Road, built in 2000 per NBI.

Posted June 1, 2019, by David P Baldwin (Baldwin24 [at] verizon [dot] net)

The Guy West Bridge was built in 1967 to connect the California State University Sacramento to its housing and business center on the other side of the American River. It was named after then University President Guy West. The bridge is not designed for regular motor traffic. It is a foot bridge, bicycle bridge. It can accommodate small motorized vehicles like golf carts and parking shuttles, but these are most likely limited to and by the city university grounds. It is designed as a replica and follower of the much larger and more famous Golden Gate Bridge, and is a true icon of itself. Picture shows original paint. The bridge has since been repainted in bright fire engine red.

Posted June 1, 2019, by David P Baldwin (Baldwin24 [at] verizon [dot] net)

This must have been the tunnel used in the 1971 movie "Duel" The scene when Dennis Weaver-(Mann) meets the school bus with Lou Firestone, and the big gas truck that has been chasing Mann in his red Valiant can be seen at the end of the tunnel.

Posted May 26, 2019, by Erik Hoffman (norcalroadswebsite [at] gmail [dot] com)

Bridge is still standing. I think the Valley Fire, which burned through Middletown and around the bridge immediately before the selected replacement date, may have delayed or cancelled the project. It may have even lowered the traffic over it enough to made replacement unnecessary, or at least less immediate, in the county's eyes.

Posted May 17, 2019, by Nathan Holth (webmaster [at] historicbridges [dot] org)

I've visited this bridge, it functions as a truss. Photo #16 shows the transverse floorbeams which indicate that the trusses are indeed functioning to handle live loads. The longitudinal deck stringers bear on the floorbeams.

Posted May 17, 2019, by Erik Hoffman (norcalroadswebsite [at] gmail [dot] com)

Are the trusses on this even load-bearing? The "floorbeam" system on this looks more like load-bearing stringers to me.

Posted May 11, 2019, by Irvin M. Ferguson (irvman57 [at] gmail [dot] com)

My Father was one of the Foreman who built the Coronado Bridge. He was always proud of that. I was looking for a list of workers for the Bridge. My Dad Oscar C. Ferguson died in 1989 in Arizona here.Miss him every day still...and Im 61. He was a hell of a good man and Dad. One day he brought home a piece of Pile steel which was one foot long and five or so inches wide and weight 80 lbs. he got permission to bring it home as a memento from the steel that was going for the bridge. I think he said they had to cut a pile down to size and he kept the one piece that came off. They said that was fine. I still have it here as a remembrance of Dad and what he helped build. During the 1970 earth quake that dropped bridges in L.A. he helped rebuild those too. Sincerely Irv Ferguson.

Posted May 9, 2019, by Kirk J Poole (kjpportland [at] gmail [dot] com)

Does anyone have the contract details for the 1915? build or the 1924? rebuild? I'm very leery of both dates with a 30' wide deck?? The railings look more like 1930's-era rail. I would supposition that this bridge, in it's current form, was built in the 1930's. In the meantime, I'll keep looking into this bridge.

Posted May 8, 2019, by Kirk J Poole (kjpportland [at] gmail [dot] com)

Does anyone have the contract details for the 1915? build or the 1924? rebuild? I'm very leery of both dates with a 30' wide deck?? The railings look more like 1930's-era rail. I would supposition that this bridge, in it's current form, was built in the 1930's. In the meantime, I'll keep looking into this bridge.

Posted May 8, 2019, by John Marvig (marvigj27 [at] gmail [dot] com)

Glad to see this one still exists and has been preserved.

Posted May 8, 2019, by John Marvig (marvigj27 [at] gmail [dot] com)

Unfortunate that this one is gone. It appears the trusses date to the mid to late 1880s.

Posted May 8, 2019, by Stephanie van steen (Mustangboss1987 [at] gmail [dot] com)

Leslie i live right by the bridge. Would love to see some photos of it being built.

Posted May 7, 2019, by Rick Donaldson (mgy2 [at] aol [dot] com)


I did a little research on the subject viaduct to determine when it was bypassed by the present alignment of Highway 101. Based on a newspaper article in the Ukiah Daily Journal, dated August 17, 1982, the bypass around the old viaduct, sometimes called "the Slab" was scheduled to be completed by August 19, 1982, but was opened to traffic by August 17th that year. I drove on the old viaduct many times while attending Humboldt State University from 1972 to 1974.

Rick Donaldson

Spokane, WA

Posted May 6, 2019, by Craig Philpott (craigphilpott63 [at] gmail [dot] com)

this is such fantastic news on the re-use of the original bridge.

Shelly Bridge (California)
Posted May 6, 2019, by Russell (stun1974 [at] yahoo [dot] com)

Apparently this bridge was named after my great grandparents-One of which migrated from the Azores (Portugal). They changed their last name to Shelly while living in America...

Posted May 5, 2019, by Erik Hoffman (norcalroadswebsite [at] gmail [dot] com)

Location is correct. Bridge is called Mono Hot Springs Bridge. In my knowledge, it's just a Bailey pony truss.

Posted May 5, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

This is a beautiful and well-aging span that should be able to go on serving traffic for decades. Does appear to have received an abutment rehab at some point.

Posted May 5, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

I live in the area so you can contact me at if you need any road information. If you're going to visit this bridge, just be advised that Jordan Hill coming from the southern (Concow/Parkhill) end is extremely rough so it's better to visit it via the northern (Paradise/Magalia) end.

Posted April 23, 2019, by Anonymous


Posted April 22, 2019, by Daniel


I have several bridges I want to look at on/off Quincy-LaPorte, maybe I'll make a longer trip and include this one too, and any others in the region I find.

Posted April 22, 2019, by Daniel

I know it's nothing special, but when I find suspension bridges (even footbridges) in the middle of nowhere I like to add them.

Posted April 22, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

It doesn't "need to get replaced" thank you very much. If it's no longer operated as a moving span, that's because it doesn't need to be. It's still a perfectly useful bridge in good condition.

Posted April 22, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

By the way, I know this is mostly a UCEB, but I figured I'd keep this here to contrast with the pony truss upstream & avoid future confusion.

Posted April 21, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

The location of the primary creek channel under this bridge has shifted since its completion, placing the entire northern span over typically dry floodplain and vegetation, and placing the southern abutment and approach road almost directly in the creek's path. As such, I worry that that 'project' may be a replacement. However, the bridge is well maintained, and recently repaved and redecked, which makes me hope that the project is not a replacement but instead a project to repair erosion to the southern abutment and approaching road, which has to be done by the county every 15 years or so at this point. It's six years after that project was supposedly 'current', and the bridge is still here. Replacements are often delayed, but not by that much - at least not without some sign of progress, which there has not been. So I think it's safe for now, but as the creek keeps moving, its days might be numbered.

Posted April 21, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

Possibly a casualty of the Carr Fire...

Peltier Bridge (California)
Posted April 21, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

Possibly a casualty of the Carr Fire...

Posted April 19, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

UPDATE: Reports of deck being destroyed turned out to be untrue, bridge was confused with a modern pedestrian truss bridge. I genuinely have no idea how it was that wrong, but here we are. Bridge is spared and open to traffic.

Posted April 19, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

Yea, I contacted the webmaster and had it changed.

Posted April 18, 2019, by Daniel

Is there a way to change the default photo displayed to yours?

Posted April 18, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

I added another page for that bridge, it's a bit downstream and from a picture I found a while ago it appears to be a wooden-decked Warren pony truss, circa either 1910 or 1940 ish. For whatever reason I can't seem to relocate that picture but if I do I'll add it to the page for that bridge.

Posted April 18, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

I dug up an old photo from a couple years ago.

Posted April 18, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

It's not open, there's a modern bridge next to a historic one, the modern bridge is open to cars and the old bridge (to which this page refers) is open to pedestrians.

Posted April 16, 2019, by Clark Vance (cvance [at] dogmail [dot] com)

The spillway elevation was raised from 187' to 300' in 1963. Prior to this time there was a crossing of the upper lake at the bottom of section 22, so a possible earlier location for this bridge. The earlier, lower level lake did not have a road across the spillway.

Posted April 16, 2019, by Tony Dillon (spansaver [at] hotmail [dot] com)

I agree Luke, I don't see anything to suggest the endposts extend down to create truss legs.

Posted April 16, 2019, by Luke

Doubtful, as a bedstead has legs that function as support/substructure, and this appears to be more of a case of vertical endposts.

Posted April 16, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

I feel like this could technically be reclassified as a bedstead Pennsylvania through truss - perhaps the only on on the site - because the end posts do act like those of a traditional bedstead in this relocated single-span scenario.

Posted April 16, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

Figured I could provide some more insight (local here):

The pony is on the actual Scales Road, which is a gravel road maintained by Yuba County.

This concrete bridge is not historically notable, and is on a Forest Service road about 5 miles downstream ALSO called Scales Road.

The collapsed road is the Forest Service one.

The pony on the county road was recently bypassed and kept open for pedestrians.

Adding to the confusion, the gravel county road is considered by the Forest Service as part of their road network, so they have assigned it a USFS number as well as the other Forest Service road.

But the gravel road is still county maintained.

Posted April 16, 2019, by Daniel

Ok, to explain the confusion... lists the road with the pony as 20N63 Old Scales Road

the photos already here are from the road closed due to the landslide, 20N35, listed above as Scales Road.

I'll edit the location of this bridge to represent where the photos were taken. The name is reasonable.

I'll then create a new bridge to represent the location with the pony (and very modern UCEB next to it), called Old Scales Road Bridge.

I feel like somewhere I read that the bridge shown here was 1959... but I'm having trouble finding where I read that.

Sorry for the number of posts related to minor stuff, I'd just like the site to be correct.

Posted April 15, 2019, by Daniel

I'm now about 99% sure that Craig's photos here are of a different location, nearby. 39.586575, -121.058286 is where I believe the photos are. The bridge appears similar to the one in the photos, and the road to it is washed out.

Juniper Lane is 2 miles SW of Scales Road, on La Porte Road. It's an easy mistake to make in a remote area.

NBI says Scales is a pony truss, google maps shows what appears to be a pony truss (and a new UCEB next to it), and construction company photos show a pony truss.

What's the right thing to do? Change the name and location of someone else's bridge, so that their photos are of the right location, and create a new bridge for the location that they thought they were at?

Posted April 13, 2019, by John Marvig (marvigj27 [at] gmail [dot] com)

Nice work! Looking forward to more on this bridge!

Posted April 13, 2019, by Luke

Excellent news, Robert. Looking forward to it.

Posted April 13, 2019, by Robert Schwemmer (Robert [dot] Schwemmer [at] gmail [dot] com)

I just measured the span, 198 feet. I believe I have identified the builder and its original location on the Colorado River. More to come

Posted April 11, 2019, by Luke

There's several dams already added to BH.

Posted April 11, 2019, by Daniel

Hurdygurdy Creek Bridge, Del Norte County, Ca.

client: Steelhead Constructors

Falsework for 2 span box girder bridge and design of temporary bridge for traffic detour.

I suspect this bridge has been lost.

Posted April 11, 2019, by Daniel looks like it was most likely replaced, so I'm seeing this bridge and it's replacement.

But... scratch that. I don't believe the location of the photos here is correct, unless there's somewhere else that Scales Road crosses Slate Creek. has a photo showing a bridge with a pony truss as well as something else (in the configuration I'd expect) being replaced by a UCEB. I'll attach the photo. Also attaching a photo with the foundation in but not falsework.

Posted April 11, 2019, by Daniel

Google Maps Satellite View shows what I suspect is a pony truss just upstream. Am I looking at it wrong?

Or... is the bridge shown here the smaller bridge visible, and the current bridge an even newer one? Bing Maps doesn't show the larger bridge, so I think that's the most likely scenario: the bridge in the pictures here has been abandoned in place. On the southern side of the western span I see what sure looks like trusswork, but maybe I'm wrong.

I also see a dam not far upstream that I might have to check out next time I'm in the area. Is there a site similar to this for dams?

Posted April 10, 2019, by Daniel

Craig, is the road in decent shape or is it pretty bad from the recent weather? I'm assuming you came from the East.

Posted April 9, 2019, by Daniel has some info on damage that occurred due to flooding in 1999

Various internet sources state that the Yosemite region had significant flooding in 1937. I think the most likely scenario is that the bridge I posted below was destroyed in the 1937 floods and replaced by the existing bridge. This flood was in December 1937, so that would likely put the existing bridge in 1938 (or later).

An initial survey of the damage included the loss of the Cascade Bridge, several miles of damaged roads, re-channeling of the river alongside the power house, extensive damage to the power lines that crisscrossed the Valley floor, the complete lost of the intake dam along the South Fork of the Merced River, loss of the Illilouette dam and its intake, submersion of nine sewage pumps stations, severe damage to the Arch Rock Checking Station buildings, damage to seven Valley residences, and the complete loss of twelve CCC buildings. Other damage included the loss of seventeen footbridges, including the Lower Yosemite Falls Footbridge, Tenaya Creek Bridge, three Lost Arrow Trail bridges, and the obliteration of most of the campgrounds scattered about the Valley.

Posted April 8, 2019, by Robert Schwemmer (robert [dot] schwemmer [at] gmail [dot] com)

Recent video of the bridge

Posted April 4, 2019, by Nathan Holth (webmaster [at] historicbridges [dot] org)

Daniel: Very interesting. I agree with your theory it looks like the bridge you found a photo of below built in 1924 was completely replaced by the bridge seen today.

Pioneer Bridge (California)
Posted April 4, 2019, by Daniel;vi... has a decent contemporary article about the construction of the new highway, including a photo of this bridge being built.

Posted April 4, 2019, by Daniel states 1924, and is from that era, but there are significant differences: the railing could have been removed at some point, but the towers appear different as well, with the legs splayed more in the 1924 photo, and I don't see the girders that're in newer photos. It's possible that it was damaged in the mid 30s and the current bridge erected in it's place in 1937.

Posted April 4, 2019, by Daniel

I have no knowledge of the date beyond the sources I linked. states:

This section was completed in January, 1924. A suspension bridge was constructed to transport supplies for highway work from the railway station, which replaced the old narrow foot bridge.

I'm attaching a photo from there as well.

Posted April 4, 2019, by Nathan Holth (webmaster [at] historicbridges [dot] org)

National Bridge Inventory gives 1936 construction date, reconstructed 1999. Not sure if thats accurate, someone here is saying 1926.

Posted April 3, 2019, by Daniel

They refer to fire trucks... I don't think a fire truck could make it up that road as is anyway.

I was on it a few weeks ago, on a motorcycle. When there was an oncoming pickup (not even a dually), we had to direct him to within 6" of the dropoff (very steep) and then we rode in the ditch on the uphill side to get around him.

I hope it's left in place, as Iowa Hill was.

Posted April 2, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)
Posted April 2, 2019, by Daniel implies that the bridge was in place by 1926 (when the store was moved across the river). It also has a photo which i'm attaching. states that the bridge was installed in 1926, so I'm adding that as a date.

Posted March 28, 2019, by Daniel

Can anyone tell me why the photo size was halved when I uploaded it? It was already small, at 800x450, but is now 400x225. I've seen photos hosted here larger than this originally was too. is the original.

Posted March 27, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

UPDATE: That is indeed the case, the land is privately owned, but as it turns out the owners treat it as a public park and often have the gates and bridge open to pedestrian traffic.

Posted March 18, 2019, by Daniel

I would guess that the gates are there to allow landowner access, and that it's now all private property.

Posted March 17, 2019, by Erik Hoffman (edh4801 [at] gmail [dot] com)

What i meant by them not being permanent is that when a road is permanently closed it is usually deliberately blocked off with dirt or a concrete wall or both, and all this has is a gate held shut with a padlock.

Posted March 13, 2019, by Michelle Miller (michellebot [dot] kbf [at] gmail [dot] com)

I remember being very young (1980's) and my grandpa took my sister and I to this bridge. The water was low enough that we walked all the way across. I can't find anything about that time, though. I remember being bored and tired of walking but my grandpa told us how special it was to be able to walk on the bridge because it is usually underwater. I was hoping that maybe someone has some pictures from that time.

Posted March 1, 2019, by Dana and Kay Klein

Daniel, DOES appear to be GM commercial bridge. Any input from sure eyed pontists?

Posted March 1, 2019, by Daniel

I thought the commercials were generally Bixby rather than Rocky Creek

Posted March 1, 2019, by ..............justsayin

GM commercial bridge?.....

Shoofly Bridge (California)
Posted February 20, 2019, by Luke

From 1986:

"According to the Plumas County Road Department its proposed plan to move Shoofly Bridge to provide access to Greenville Park has been abandoned in favor of building a new steel bridge. The Road Department also considered purchasing a bridge from outside the county, but their efforts acquire an old bridge in Amador County met with the same resistance by historical groups there as the opposite by Plumas County's Historical Society to dismantle and move Shoofly Bridge."

Posted February 19, 2019, by LOCALYOCAL

Known as the "Shoe Fly Bridge". Kansas City Bridge Co. Pre 1900 I believe. Old stage road bridge then vehicles before state rte. 89 was connected at the Wye. Pvt. prop. on north side but short easy hike off to the side if you follow the trail. Longer drive from south on Quarry Rd. (Travertine quarry) Great swimming hole underneath.

Posted February 18, 2019, by Daniel

I wasn't sure either, so I didn't change it. I'd probably have changed it to derelict/abandoned rather than lost. Not sure that it's *right*, but seems more accurate than lost.

Posted February 17, 2019, by Tony Dillon (spansaver [at] hotmail [dot] com)

If the superstructure (trusses) are still standing then the bridge should not be classified as "Lost".

Posted February 17, 2019, by Erik Hoffman (norcalroadswebsite [at] gmail [dot] com)

I'm honestly not sure- it's lost for the time being i suppose, but not permanently. Unless it is permanent, because the road it's on is private and not well traveled and Butte County is notoriously stingy with infrastructure funding.

Posted February 7, 2019, by Daniel closed due to deck spalling again

as far as seismic goes: Carquinez is significantly newer than the Bay Bridge. 1958 vs 1936. They also did a significant seismic retrofit on the 1958 bridge when they opened the 2003 bridge, before they demolished the 1927 bridge. A full, medium term closure isn't something they could do on the Bay Bridge, but at Carquinez they had the opportunity to do so.

Blue Nose Bluff (California)
Posted January 30, 2019, by Luke

This page on has a picture that a contributor who has an account will add later.

In the meantime, I'm going to merge the build date.

Blue Nose Bluff (California)
Posted January 30, 2019, by Doug Cole (guestranch [at] marblemountainranch [dot] com)

Hoping to find a historical photo of this bridge at Blue Nose Bluff, which was lost in the 1964 floods.

Posted January 30, 2019, by Jesse Hendrix (jland1111 [at] yahoo [dot] com)

This is the tunnel shown in the 1974 made-for-TV movie the California Kid. Wikipedia mentions it was filmed in Ojai and Piru but there's no tunnels in those areas.

Posted January 21, 2019, by Daniel

Where was the gate, right at S Fork/Grouse Valley? Any associated signs? That sure appears to have been open to the public previously, and Bing has street view of the new bridge from 2015 with no indication of a gate.

Posted January 21, 2019, by Daniel that has a 1966 photo where the bridge looks lower than it is now. Given that there some realignment on that road in the late 60s (there are multiple sites along it with bridge abutments and piers, with the road now downslope from them, topos seem to change in the late 60s), I wonder if they raised it somewhat at the same time.

Posted January 20, 2019, by Craig Philpott (craigphilpott63 [at] gmail [dot] com)

Attempted to view bridge, road now appears to have locked gate, no access.

Posted January 15, 2019, by John Doyle (mejaydee [at] verizon [dot] net)

Thanks to everyone for the comments about Nelson Bar Bridge and the photo. I tried to find a photo in my files, but the best I could come up with is a frame from an old 8 mm movie.

UP - Tunnel 0 (California)
Posted January 15, 2019, by Clark Vance (cvance [at] dogmail [dot] com)

Photo 2 shows lining into the first several feet. People sometimes make nistakes....

UP - Tunnel 0 (California)
Posted January 15, 2019, by Daniel

Tunnel "0" is an abandoned, unlined single track railroad tunnel, approximately 800 feet in length and of inverted horseshoe section, with granite ashlar portal faces and wingwalls, and a stone masonry-lined bore.

I'm a little confused about that part. It's unlined, but it's masonry-lined?

Posted January 14, 2019, by Daniel

Am I missing something? This doesn't look like an arch. I'd guess box girder.

Posted January 14, 2019, by Mary Costello (auntrare45 [at] gmail [dot] com)

Stuck again for 3rd day in a row!!!!! Cancel everything !!

Also regret buying in the delta area due to constant bridge problems that are never fixed, constant work on 160. Almost two years of 1 lane for bridge being painted and now it doesn't work most of the time again!! What a humilation for Caltrans!

Posted January 13, 2019, by Luke

They're the same pics with newer URLs. Note how the latter part of the strings are the same in both those and the dead links.

Posted January 13, 2019, by Daniel

the image links no longer work. I found 2 in the RRHS photos of Monte Rio (well, they appear to be the same image, with some work done on one of them). Not sure if they're the same or not.

Posted January 13, 2019, by Daniel

These were present on some but not all of the round tension members (the bridge has some round and some rectangular tension members). While some were at midpoints, one weren't (the one I took a picture of). Then again, on one of them one side of the brace was no longer attached, so it's possible that they were all originally ad midpoints.

I didn't think to look at whether Haupt Creek or Gualala have any round tension members. I have a picture of the repair on Haupt Creek and it's rectangular. The other photos I took aren't good enough for me to determine if any of the tension members are round.

I also noticed 2 locations on this road where there used to be bridges parallel to the road, with foundations still present and the road now downhill of the foundations. I'm curious as to what went on there. The region sees a lot of ground motion, to the point that there were I think 8 sections that are now gravel (some of which are paved, with a centerline, on both sides of the gravel), I wonder if they decided it was cheaper to move it rather than maintain the old bridges.

I'm also a little surprised that none of the 3 have any posted weight limits. I'm not sure if you could get a typical semi to this one, as there are some very significant angle breaks on the road and I'd be afraid of high centering, but Skaggs Springs you absolutely could.

Posted January 13, 2019, by Art S. (asuckewer [at] knite [dot] com)

My guess (based on engineering logic but not experience) is that its some sort of rig to tune the bridge or a way to reduce the resonance for seismic activity protection.

The bridge seems to have lost much of its original detail so some of the original mechanisms to adjust the tuning/loading of the tension members may not function and this could be a patch. If the tension members are pushed apart, it may help in keeping the tension evenly distributed between the two members (the looser rod will bow out more than the tight one) if the adjustment devices no longer work.

Also, by connecting the tension members at their midpoint, the resonance frequency is increased and the amplitude is reduced (the seismic reason).


Art S.

Posted January 13, 2019, by Daniel

Any guesses as to what these are for? They were on a few braces, in different locations.

Posted January 12, 2019, by Luke

Bracing could make it function more like a rigid frame vs a simple stringer.

I'll like the engineering types decide that tho.

Posted January 12, 2019, by Daniel

Any input on type? I'd call it a steel stringer bridge, but I don't know if the braces change that.

There's a gate on the road that restricts access down to the bridge itself, hence no closer photos.