Industrial History

Saturday, April 25, 2026

1911,1918 Fernbridge over Eel River near Fortuna, CA, was largest concrete bridge

(Archived Bridge Hunter; Bridge Hunter; Historic Bridges was broke; Satellite)

Bridges Now and Then posted
"Building Fernbridge (Fortuna, California) in 1911. When this 1320-foot bridge was built in 1911, it was referred to as the world’s largest all-concrete span. Also called Eel River Bridge, Fernbridge is listed on the National Historic Register for its engineering significance during the period of 1900 to 1924." (USGS)

BridgeHunter has the stats of 2408' (734m) long with a span of 195' (59.4m). It also provides a rehabilitation date of 1918.

BridgeHunter

That strikes me as rather shallow arches.

BridgeHunter

BridgeHunter, 2009 photo by Craig Philpott

BridgeHunter, 2018 photo by Mike Goff

I wonder what rehabilitation work was needed just 7 years after it was built. I checked out Wikipedia. The work replaced wooden approaches with the current concrete ramps. I also learned that this bridge "is still the longest functional poured concrete bridge in operation in the world."

1927,1988 C.L. Schmitt (9th Street) Bridges over Allegheny River at New Kensington, PA

(Archived Bridge Hunter; Bridge Hunter; Historic Bridges; pghbridges; Satellite)

Dan Felack, Jul 2021

Jackson-Township historical preservation posted

Photo showing the construction of a new bridge crossing the Allegheny River as well as the existing old bridge at New Kensington, Westmoreland County in 1926-27. This photo is from the Alle Kiski Valley Historical Society Museum located in Tarentum.

(Photo from Raymond Rieser via https://www.facebook.com/groups/232382343450800)

HistoricBridges
"The bridge is an extremely late example of a pin-connected truss bridge."

This photo shows the bridge design was a transition between pin connected and riveted because it uses both technologies.

2010 photo by Jason Smith via BridgeHunter

Street View, May 2025

pghbridges
"The bridge is named for the late C. L. Schmitt of New Kensington who served in the Pennsylvania State Legislature for 16 years. He served for the 54th District and is noted for working to establish the PA Consumer Credit Act, a model for the Federal Truth in Lending Law."

Friday, April 24, 2026

1931 Echo Dam on Weber River near Coalville, UT

(Satellite)

Bureau of Reclamation posted three photos with the comment:

A closer look beneath the surface at Echo Dam:
What started as a routine day became a major discovery when a dam tender spotted unusual conditions earlier this year. After water levels were lowered, crews found large concrete slabs had been lifted and shifted by powerful flows from the spillway and outlet works into the stilling basin.
The Bureau of Reclamation and partners, including the Weber River Water Users Association, quickly investigated and determined the slabs were not fully anchored and had been displaced over time. Crews installed nearly 90 deep anchors, each about 30 feet long, to secure new concrete and improve long-term performance.
Repairs were completed ahead of schedule, helping ensure the dam remains safe, reliable and ready for future high-water events.

Rick Kuter: Let's hope the future includes some high-water events. Definitely not a problem with this winter's snowpack, or lack thereof.

Mike Kluth shared

Evidently, the building is an outlet control works valve house rather than a powerhouse.

Photo via StateParks

The spillway gates are on the far side.

Street View, Jul 2024

The spillway is on the far side in this view.

Street View, Sep 2024

usbr
"Echo Dam is a zoned earthfill structure, one mile upstream from the town of Echo and about six miles north of Coalville. It has a structural height of 158 feet [48m] and contains 1,540,000 cubic yards of materials. The spillway has a capacity of 15,000 cubic feet per second. The outlet conduit is a concrete-lined horseshoe tunnel to the gatehouse, from which two steel pipes pass through a tunnel to the valve house. The outlet works has a capacity of 2,100 cubic feet per second."

Hennepin Canal Lock #15

(Satellite)

Hennepin Canal Overview

Hennepin Canal State Park posted
Today's Throwback Thursday photo shows lock tenders and their families at Lock 15 (located between Wyanet and Tiskilwa) in the early 1900s.

Jacek O, Oct 2021

Thursday, April 23, 2026

1.2mw Trego Dam on Namekagon River near Trego, WI

(Satellite)

Saint Croix National Scenic Riverway posted

Xcel Energy will conduct a semi-annual test of the dam failure warning sirens below Trego Dam on the Namekagon River today, Monday April 6th, at 11:00 am. The test will last about 90 seconds and involve a series of audible tones and messages. The test is in coordination with Washburn County Emergency Management, the National Park Service, and local townships. Anyone with questions about this test should contact Xcel Energy’s 24-hour Customer Contact Center at 1-800-895-4999.

Image: Trego Dam/NPS. In the middle of the image to the right, water rushes over the concrete dam into a pool of bubbling water of the river creating white and rusty color foam. The remaining concrete structure of the dam is in the background topped with green grass and trees.

George Scott: There are many smaller dams in Wisconsin that have been abandoned or are receiving minimum maintenance. A number of years ago a dam in DD Kennedy park on the Balsam Branch in Polk County partially collapsed causing a 6 foot crest to roll down stream into Lake Wapogasset and the Apple River. A few years before that another dam near Osceola collapsed causing the closing of Wisconsin 35 for about a year.

HydroRelicensing
The installed capacity is 1.2mw.

Cassie Baier posted
The dam in Trego Wi

stcroix360
Another alarm test notification

CSX/C&O and KY-644 Bridges over Levisa Fork of Big Sandy River near Walbridge, KY

1914 C&O: (Archived Bridge Hunter; Bridge Hunter; no Historic Bridges; B&T; Satellite)

1883 Road: (Archived Bridge Hunter; Bridge Hunter; no Historic Bridges; B&T; Satellite)

1883 Tunnel: (B&T; Satellite)

Street View, Jul 2025

In 1914, C&O completed a new, longer bridge that did not need a tunnel and that reduced the curvature of the route. The road bridge and tunnel on this map were the original railroad route.

1953/55 Louisa Quad @ 24,000

Bridges & Tunnels by Sherman Cahal posted four photos with the comments:

Kentucky is a state with few 19th-century historic trusses remaining in its statewide bridge inventory, and the eastern half of the state has very few original roadway trusses remaining in general. That’s why it was surprising to come across fairly rare King Bridge Company trusses with Phoenix columns in Walbridge, Kentucky.
⤐ View the newest journal entry at Bridges & Tunnels at http://bridgestunnels.com/.../the-bridges-and-tunnels-of.../
⤐ c. 1883 bridge: http://bridgestunnels.com/location/walbridge-bridge/
⤐ c. 1883 tunnel: http://bridgestunnels.com/location/walbridge-tunnel/
⤐ c. 1914 bridge: http://bridgestunnels.com/loca.../walbridge-railroad-bridge/

Bridges & Tunnels by Sherman Cahal shared with the comment: "A former railroad alignment south of Louisa, Kentucky, has been reused for a state and county road."