Auger Cast Piles or Continuous Flight Auger (CFA)

Some contractors working on the Miami Signature Bridge bragged about pioneering the use of "auger cast piles" for building bridges in the US. A comment by mkeit on those notes taught me that the technique is also called Continuous Flight Auger (CFA). Using many piles under a foundation has been the solution for many decades as to how to hold up heavy structures. Either the piles go down to bedrock or they are long enough to create enough friction to hold the structure. Initially, the piles were wood poles driven into the ground. Then H-beams and precast concrete columns were driven. But when the piles are really thick, they can't be driven. For thick piles, a hole is bored into the ground and then filled up with reinforced concrete. The drills I have seen have an auger with just a few turns on the end of a long shaft.

Screenshot

The auger is lowered into the bore and the shaft is turned until the auger fills up with material. Then the auger is brought up out of the bore, the unit turned to its side and the auger is spun to fling the material out of the auger. Then the cycle is repeated by placing the auger back into the bore. If the soil is not competent, then a steel casing has to first be driven into the ground to keep the soil from collapsing back into the bore being dug. Once the bore is dug, a rebar cage is lowered into it, and it is filled with concrete.

Continuous Flight Auger uses an auger that is a long as the desired depth of the bore and that has a hollow shaft. It allows drilling bores in incompetent soil without the need to first drive a casing into the soil. It also removes the dead time of raising the auger out of the hole every few feet to discard the material. Since a picture is worth a 1000 words, this video explains the process.

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This video explains the process using real equipment.

(new window, 4:30)  (It is a shame that they play the torture music during the narration. In one case, it actually drowned out some of the words!)

Skyscraper Foundations in a Swamp (Piles)

This was one of the first topics I had planned on writing about when I started this blog in 2014. I've been accumulating photos for drilling the piles for years, but never found the time to research it. I knew from a tour of Northwestern University's Tech Center in 1967 that a lot of research was done to figure out how to safely build in a swamp. They had a plexiglass 2' cube filled 2/3rds with sand. And they added water to the sand to emulate the soil conditions of Chicago. The tour guide picked up scale model houses and other buildings and set them on the sand. They did not sink into the sand. But, while he was talking so you didn't notice, he picked up a rubber mallet. Then he said it was not hard to keep buildings on top unless there was an earthquake. When he said "earthquake," he hit the side of the cube with the hammer and all of the buildings disappeared into the sand! (That explained why all of the buildings had wires attached to them so that he could easily pull them out after each demonstration.) The guide then explained the issue of soil liquidation during earthquakes. Foundation expense is probably why the Prudential building was the only big, tall building in Chicago for decades.

The solution is to create a lot of piles in the soil to spread the load and to create a lot of friction. Originally, the piles were driven in the ground. But as the piles became thicker and/or deeper, they could not be forced into the ground. So a bore would be drilled into the soil and filled up with reinforced concrete.  These notes cover the original boring technique. A new technique for creating piles is Auger Cast Piles or Continuous Flight Auger (CFA).

I'm publishing now because I found this article that has done the research for me.

safe_image for Building Skyscrapers on Chicago’s Swampy Soil

[I learned near the end of  this article that the foundations for most of our modern buildings go to hardpan, not bedrock.]

Comments on Daniel's post

David Daruszka commented on Daniel's post
Some older buildings did settle unevenly. Case in point The Gage Building. The right set of bays droops slightly due to settlement.

I remember reading that the foundation for the Kinzie Street RR Bridge was a 30' deep caisson built on top of 90' piles into the bedrock.

I did end up going to Northwestern University to get my Electrical Engineering degree. When I arrived in 1967, they had built the landfill. But the only buildings on it were the planetarium on the northwest corner of the fill and a one-story computer center building that housed our CDC 6400 computer. I knew the planetarium had been torn down because light pollution made it worthless. Looking at a satellite image, it appears the computer center got torn down to make way for the Patrick G. And Shirley W. Ryan Hall. While I was at NU, the new library building was built on the landfill. After I graduated, I heard that the new library was sinking because the architect had not included the extra weight of library books. A quick Google search indicates that this was an urban myth and that the architect was Walter Netsch. [WTTW] This is a common myth concerning many university libraries. [WTTW, snopes, metafilter] I remember watching the TV show of "How I Met Your Mother" when the architect character talked about the risk of making a mistake. As an example, he cited the mistake of a library sinking because the architect forgot the extra weight of the books it held. (The character was Ted Mosby. [StevenDavis])

And now for the collection of photos of drilling the holes for the deep piles.

John Nawakowski -> Forgotten Chicagoto

 Forgotten Chicago

Foundation being laid for Marina City. Chicago,1961

Josh Davis posted

Building 167 W Erie

[Note the auger is laying in the foreground.]

Estructurando posted

Jim Smith posted

J J Novak posted

A video link from the above posting showing "a powerful drilling attachment for deep caisson foundations" in action.

Mike Haggard posted two photos.
Victor Ronquillo Are y'all drilling through granite ?

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2

Mike Haggard posted

Old girl needs some new paint !!

Sean Stewart Very nice, not often you see a 4100 drilling shafts, feel free to share more at facebook.com/groups/pile.driving.and.deep.foundations

This is the first time I have seen long augurs that allows the pile driver to run continuously.

Screenshot

(new window, 4:02) At 1:37 you can see him turn the auger to fling the dirt off. In practice, the auger would be full of dirt and a lot more dirt would fall off. At 2:08, I don't know that that hydraulic press would normally be used for.

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17:29 video @ 8:00
Practical Engineering
"An overview of the different types of pile foundations and how they work."

5:54 video of a steam driven pile driver

I never thought about how you start a diesel fuel pile driver. Watch the second video in this post.

A dramatic demonstration of frost heave

When we built our deck, we had to use a power auger to drill holes 3.5' into the ground under each footing and fill them with concrete. In the Chicagoland area the building code used to require just 3'. But the three bad winters we had at the end of the 1970s froze the ground deep enough that they added another half-foot to the required depth so that the bottom of the piles would be below the depth of the frost line. It turns out, it was pretty easy drilling 3' deep. But that extra half-foot was a pain. The soil kept dropping back into the hold. I finally used the shop vac to get enough dirt out to meet code. Note in Eric's photos below that it has pushed the old piles three or four feet out of the ground!

Eric Kurowski posted two photos with the comment:

Simple little deck bridge on the C&NW . This once was a small wood trestle. Was rebuilt a few times the Masonry of the big limestone blocks was original. The frost is pushing up the ORIGINAL piles in the middle that were once cut off below the waterline.Now this bridge has steel grates for deck and steel I beam for span replaces the wood timbers.

Dennis DeBruler I've heard of frost heave before. But I didn't realize that it could be so dramatic.

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All three of these videos talk about ice lenses forming in the soil. They are what creates an upward force, not the 10% expansion of water when it freezes. When water freezes, it drys out the soil below it. This dry soil sucks water in more water from the wetter soil below it with a wicking, i.e. capillary, action. This new water then freezes making the ice lens deeper. That again drys out the soil causing even more water to come join the party. So an ice lens will continue to grow and push the soil upwards as long as the temperature is below freezing and there is more water to pull out of the soil.

Ice lenses can form only in certain types of soil. If the soil is too porous, i.e. sand or gravel, it is well drained and doesn't hold the water long enough to freeze. If it is too impermeable, i.e. clay, it doesn't allow water to wick upwards and "feed" the ice lens. That explains why our building codes required a thick bed of gravel under our new concrete driveway.

Rocks conduct cold better than soil. So a rock will form an ice lens under itself. That explains why my grandfather had to pick rocks out of his farm fields year after year for many years.

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A video showing various machines to remove rocks from fields

1904+2022 BNSF/NP Bridge over Lake Pend Oreille at Sandpoint, ID

(Bridge Hunter; Satellite)

It looks like the bridge is on the mouth of the Pend Oreille River to me. But since all the sources I found indicate it is over the lake, I'll go along with their nomenclature.

Jabos Menis posted
A Northern Pacific train going across Lake Pend Oreille near Sandpoint, Idaho. Opened in 1904, the bridge is still in use today. An identical bridge was constructed adjacent to the older bridge and was completed only several years ago. Photo of train going over bridge from my collection and dated 1918.

Jason Rasor: Back when it still swung.

Jason Rasor: Google says it can still swing if it needed too. [It must have been Google's AI summary because I think this is wrong. I looked at a satellite image and could not find a swing span. And the new bridge certainly doesn't have a moveable span.]

Chad Inman: I jumped off that trestle many times....in the dark. We would get arrested trying to do it in the daylight.

Steven J. Brown posted
A BNSF intermodal crosses Lake Pend Oreille at Sagle, Idaho - May 15, 2004.

Ian Lothian posted
I've always had a ' thing ' about photographing bridges and viaducts and this was one that I had had on my things to do list for quite a while. A westbound BNSF manifest is crossing the Lake Pend'Oreille bridge with Sandpoint Idaho in the distance.

A view from the other end:

Ken Edmier posted
An eastbound Intermodal train crosses Lake Pend Oreille at Sandpoint, ID. 8/1/2019.

Stevie Knox commented on Ian's post

William Brown posted
From the J Quinn Collection, it is 1973 and a BN Freight with GN GP35/SD45/F45 locomotives is crossing the bridge at Sandpoint, Idaho. A Train full of 40' Boxcars and 40' Covered Hoppers is so different from today. The second bridge is open, and this bridge has been completely rebuilt. Mixed Freight replaced by International and Domestic Intermodal, Grain Shuttles, Crude Oil Trains. only Amtrak is the same. No photographer noted. Any help appreciated.

U.S. Coast Guard approves BNSF's Idaho rail bridge plan: RailwayAge and ProgressiveRailRoading. This federal agency was evidently the holdup because BNSF expects to begin work.

U.S. Coast Guard Illustration via RailwayAge

Bruce Kelly via RailwayAge
In June 2014, an eastbound BNSF vehicle train waits at East Algoma, Idaho, while a westbound manifest crosses the nearly mile long single-tracked bridge over Lake Pend Oreille. Sandpoint is on the other side.

Deborah Lynn posted

Kevin Conrad posted
BNSF westbound manifest coming off of the bridge Sandpoint, ID 10-18-19
Jonathan Tuom Looks like the shoulder of Bottle Bay Road.
Kevin Conrad Jonathan Tuom yes it is.
Taylor Baggarley I can’t wait be their see double track.

Kevin Conrad shared
Kim E. Fokken what type of freight content are the boxcars generally hauling?
Dennis DeBruler Paper products.

I don't see many common boxcars or Railboxes anymore. But the white stripe at the top of the boxcars in this photo indicate they are hi-cube boxcars. They were developed to carry paper products more economically than a standard boxcar. In today's world of tri-level autoracks and double stacks, their height is no big deal. But when they were first introduced, I imagine that vertical clearances, especially on industrial spurs, were an issue.

https://industrialscenery.blogspot.com/.../new-freight...
Kim E. Fokken Dennis DeBruler I see alot of rail box and some common box cars. I think that the use of intermodal containers, I think that has made some impact on box car use
Kevin Conrad Kim E. Fokken some fine cut lumber, appliances.
Kim E. Fokken Kevin Conrad how about paints, and other coating items, hardware merchandise? Stuff that would be shrink wrapped and on pallets. That kind of processing is done with intermodal containers as well like any other truck that picks up or drops off at a warehouse or distribution facility.
Kevin Conrad Kim E. Fokken yes. The aluminum plant here uses railbox cars. Couldn't tell you what was in them. The newspaper warehouses receives paper.. sure there is allot. Not as much as years ago.

Kevin Conrad posted
BNSF Eastbound intermodal over Lake Pend Oreille, Sandpoint, ID 10-18-19

Kevin Conrad posted
BNSF bridge over Lake Pend Oreille, Sandpoint, ID

A video of an e/b tank train by Kevin Conrad from the above vantage point



Once again, NIMBY (Not In My BackYard) complainers seem to have no credibility. "Opponents called for a more rigorous analysis via an EIS (Environmental Impact Statement). They also raised concerns about derailments jeopardizing water quality, coal dust contamination and the potential impact of increased rail traffic in the Lake Pend Oreille corridor." [RailwayAge] The new bridge should reduce the risk of derailments because some of the trains will be going across a newer bridge. The same amount of coal is going through the area independent of the number of bridges that carry it. If anything, it will reduce coal dust because coal trains won't have to set on a siding waiting their turn to cross. It will reduce the impact of traffic on the local area because the trains can go through the town rather than have to stop and wait their turn. And with the coal market plummeting, traffic is probably going to go down anyhow.

Update:

Art Wigton posted
When the BN became a railroad seeing pictures like this was common engines in different colors. Looks like the BNSF was having the same issue. Sandpoint Idaho.
Gary Dowler They were commonly called Zebra trains back in the early 70's. Any given freight might have had something like a CB&Q F-7, a Burlington Route SD-24, a SP&S C-425, a GN U-33C and an NP SD-45.

Watching trains then was like opening a box of chocolates, you never knew what you were going to get.

Art Wigton posted
Sandpoint ID April 2011 3 BNSF C44-9W 5039 611 5479 can't take this picture again. my photo

In response to a comment about the length of the bridge, Art provided this photo on his post
Brian Biekofsky posted
Autoracks in Idaho.

Dennis DeBruler

You don't see almost the full length of the Lake Pend Oreille bridge very often.

https://bridgehunter.com/id/bonner/bh58051/

Georgie Li posted
11 motors are on this eastbound manifest as it crosses the bridge over Lake Pend Orielle in Sandpoint, ID
Patrick Dempsey exGN or exNP?
Georgie Li Patrick Dempsey the RR is ex NP. I think GN took a different routing.
Sean Rotinski GN went from Hillyard-Newport and them to Sandpoint. POVAs trackage from Newport-Dover and UP from Dover-Sandpoint is the GN route north.
Zack Smith Power move.
John Grady Lots of weight all bunched up there on one train, if they were all on the head end. There used to be a limit on how many could be moved in a bunch like that; but, heck, that was almost 26 years ago before I retired.
Matt Holden Depending on the models, that's somewhere around 50,000 horsepower!
Jack Kendall I'm betting on it just being a power transfer. That much power on the front would be silly when couplers are only rated at 400,000 lbs. Unless that's changed? I'm not 100% sure on that.
John Grady In the late 70's when I was dispatching power on the Frisco and ore trains were running like streetcars out of Mobile Al (AT&N owned by Frisco) I put 12 'units' on the head end of #235 out of Tennessee Yard headed to Mobile to bring 2 ore trains and #22 out a couple of night later. When they were going into the siding at Tours (just north of Holly Springs, MS) a switch problem caused 1 unit to derail. Everyone tried to say it was because of TOO MANY locomotives on the train; but it was just a piece of bad track. Anyway, this resulted in a restriction on the number of 'units' on a train; and it was 8 (I think) Karl Brand can confirm this as he probably has the timetable (I may also have it in a box out in the garage, so if I find it will confirm the correct number). We would move extra power as part of a 'consist' so it all moved from and to the roundhouse (or service track) as a unit and did not have to moved by a switch engine. We always needed more power north out of Mobile than we did coming in with empty hoppers; as one time Ray Mashburn, engineer, came into mobile with 214 empty hoppers; enough cars for almost 5 ore trains. And he did it without getting even ONE knuckle on the AT&N between York and Mobile; and that railroad is most all up and down; not much flat ground until you get south of Mt Vernon; only about 25 miles from Mobile.

Double tracking the Sandpoint area will remove the last single-track segment on BNSF's northern route. [RailwayAge (posting)]

U.S. Coast Guard Green Lights Sandpoint Bridge Project

safe_image for  BNSF Breaks Ground for Second Sandpoint Bridge

safe_image for To build a train bridge
[They are going to use hollow steel piles and prefabricated pier caps. The steel will be thicker than normal so that they do not have to be filled with concrete. Most of the 104' girders will be prestressed concrete. But those spans over the designated US Coast Guard navigation channel will be steel. The steel girders are shallower and provides the required vertical clearance. They will cast and pour a concrete deck that carries ballasted track. Most piles will use a vibrators. Those that are hammered will use a bubble curtain to mitigate the noise experienced by the fish. They will also use turbidity curtains. Using a bubble curtain to contain noise was developed in 2005 for the Oakland Bay Bridge construction.]

In Sept 2020, I got hit with a Double Doomsday. Both Facebook and Google changed their software. I said "changed" instead of "updated" because the new software is not better. In fact, Google's Blogger software is far worse except for a search function that works. For example, it has three bugs concerning photos and their captions. So I'm no longer copying photos and interesting comments from Facebook. I'm just saving the link. Unfortunately, some of the links are to private groups.

safe_image for BNSF advances pile installations at Sandpoint Connector project

safe_image for BNSF Sandpoint Bridge Enters Home Stretch
After this bridge is done, more maintenance work will be done on the 1904 bridge.

Photo by Bruce Kelly via RailwayAge

1 of several photos from a BNSF press release  (source)
"The project is completed, and the bridge officially opened on Sunday, Nov. 20, [2022,] when a BNSF train crossed the bridge for the first time. The completed bridge is 4,873 feet in length, comprised of 49 spans, 224 precast concrete girders and approximately 55,000 feet of 36-inch pipe pile."

 

BNSF Railway posted
BNSF’s inaugural train trip across the new Sandpoint Junction Connector rail bridge over Lake Pend Oreille took place Sunday, marking the last step of a multi-year project. In late 2022, BNSF Teams completed a second mainline bridge as BNSF teams continued to perform track maintenance work on the existing bridge adjacent to the new bridge. Now that maintenance on both bridges is complete, trains will run bi-directionally creating capacity, reducing congestion and helping our customers’ freight move more efficiently to and from the Pacific Northwest. Thank you to all BNSF team members who worked on this project. Photo by Bruce Kelly, courtesy of Railway Age. 
Trains Magazine posted a slightly different photo

 

safe_image for How BNSF Minimized Sandpoint Bridge Project Environmental Impacts

If you enjoy talking heads covering the usual platitudes of teamwork, safety, complex project, community improvement, environmentally friendly, etc., then this video is for you.

Five drone photos  (shared)

Two drone photos