CN/GTW St. Clair Tunnels between Port Huron, MI and Sarnia, ON

(Bridge Hunter; HAER; Port Huron Portals Satellite; Sarnia Portals Satellite)

(Whoops, another duplicate. See Nov 12, 2017 for my first crack at these tunnels.
CN derailed 40 cars in the tunnel on June 28, 2019.)

"Built 1888-1891; Electrified 1907-1908; Electrification removed 1958: Tube sealed 1994" [Bridge Hunter]

Significance: The St. Clair Tunnel was the first full sized subaqueous tunnel built in North America. Joseph Hobson, the Chief Engineer, successfully combined three significant new technologies—a tunnel shield driven by hydraulic rams; a cast iron tunnel lining; and the use of a compressed air environment. This tunnel eliminated a major bottleneck in the rail transportation system linking the American midwest with its eastern markets. [HAER-data]

Joe Dockrill posted, 1.5x
Dennis DeBruler The illustration in the middle must have been before they got close to the river and added compressed air to the operation. For that they added a bulkhead with a 6' x 17' airlock for each track and a 10" x 25' airlock to allow long pieces of pipe to pass through the bulkhead.

The Grand Trunk did not have many options in removing this bottleneck. The volume of shipping on the St. Clair River, said to exceed that of the Port of New York, precluded any moveable bridge, such as a bascule drawbridge or swing bridge. Any structure extending into the river would need the approval of the U.S. Array Corps of Engineers. The powerful Lake Carriers' Association, representing the shipping interests, would vehemently oppose a bridge. The opposition of both organizations had quickly killed plans for a bridge across the Detroit River offered by the Michigan Central Railroad in the 1870s. Given the flat topography, a high bridge, such as a suspension bridge, would require extremely long and prohibitively expensive approaches. [HAER-data]

In 1872, Michigan Central started digging a drainage tunnel that would support a planned 18.5' double track tunnel between Detroit and Windsor. The Detroit River bed was the same blue clay that was assumed to be under the St. Clair River. But after digging 1,220' under the river on the American side and 450' on the Canadian side, the workers hit a pocket of sand and water that started filling the excavation. MC abandoned the work and allowed the tunnels to flood. Given MC's "surprise," Joseph Hobson, the GTW engineer, did eleven test borings 50' south of the intended tunnel line. The results were discouraging. The blue clay was permeated with water and the shale bedrock was porous. The planned tunnel was to have a bore of 25' lined with 2.5' of brick laid in Portland cement yielding an inside diameter of 20' But they decided to start with an 8' test bore in 1886. The Port Huron side went just 33' from the 92' access shaft before they encountered very soft clay. The Sarnia side had an 82' access shaft and that bore went 278' when they encountered a pocket of natural gas! Extensive pumping was able to keep the tunnel dry, but the work was abandoned after a couple of months of additional effort. [HAER-data]

In the meantime, Hobson did 110 borings along the tunnel line down to the top of the clay strata. He determined that the clay strata was only 38' thick in the center of the river. He decided to use a cast iron lining instead of the current practice of a brick masonry lining to reduce the needed bore from 25' to 21'. And to deal with the poor soil conditions, he used "an iron shield with hydraulic machinery to move it forward." In 1888, he tried to dig new access shafts. The American shaft was 58' and was later used as a ventilation shaft. But the Canadian shaft needed 98' and they could not keep it dry. He switched to the plan of digging the tunnel's cuts further from the river and using the tunneling shield for the approaches as well as under the river. This plan commenced in 1889. "The open cut on the Port Huron side extended 52 feet below grade, was about 200 feet wide, and began roughly 1,800 feet from the river. The Sarnia open cut was 60 feet deep, 260 feet wide, and began about 2,000 feet from the river bank." Hobson also used "compressed air to protect the workings from an influx of quicksand and water." Hobson didn't invent the shield, hydraulic rams, cast iron lining, or the pneumatic process; but he was the first to use all of them together to tunnel in soft soils. This is essentially how it is done today except steel and concrete would be used instead of iron and the digging would be mechanized. [HAER-data]

Photo (rotated and cropped) from HAER MICH,74-POHU,3--16 from mi0363
Photocopy of Engineering Drawing (original in Engineering News, 4 October 1890. p. 292), delineator unknown. Scales indicate height in feet above sea level. The gradient in the middle section of the tunnel is incorrectly labeled 1 in 100, whereas the correct gradient is 1 in 1,000. VIEW NORTH, PROFILE OF PART OF ST. CLAIR TUNNEL UNDER RIVER SHOWING SECTION OF RIVER BED AS DETERMINED BY BORINGS, 1890. - St. Clair Tunnel, Under St. Clair River between Port Huron, MI, & Sarnia, ON, Canada, Port Huron, St. Clair County, MI

Photo from HAER MICH,74-POHU,3--15 from mi0363
Photocopy of Illustration (original in Scientific American, 9 August 1890), photographer unknown. DRAWING SHOWING THE TUNNELING SHIELD AT WORK, WITH SEGMENT HOIST AND WORKMEN, 1890. - St. Clair Tunnel, Under St. Clair River between Port Huron, MI, & Sarnia, ON, Canada, Port Huron, St. Clair County, MI

"When the two shields met on 30 August 1890 after excavating 6,000 feet of ground, they were perfectly aligned horizontally and off by only 1/4 inch vertically." (The reference has considerable detail about how they achieved this accuracy.) The maximum air pressure used was 43 pounds/sq. in. or 28 pounds above normal atmospheric pressure. "Horses were unable to survive in the compressed air environment, so they employed mules to haul the tram cars loaded with clay from the workings to the tunnel portals." And they did switch the air exhaust valve on the airlocks from 4" to 1.5" because the workers were suffering, even dying, from the bends. On Jan 20, 1891, they finished all work on the tunnel. But they then had to excavate the long approaches, construct the portals, and lay the track. The excavation work had to deal with landslides. The tunnel was watertight enough that bigger pumps were needed to drain storm water out of the cuts than seepage out of the tunnel. The tunnel was formally opened in September 1891. [HAER-data]

The St, Clair Tunnel Company bought four custom heavy-duty steam locomotives to move trains through the tunnel. The Baldwin Locomotive Works of Philadelphia, the premier locomotive manufacturer of the late nineteenth century, built them in February 1891. Each locomotive had a 0-10-0 wheel configuration and were designed as camelback engines, so they could operate in either direction and thus, the railroad did not have to turn them around after each passage through the tunnel. The weight on their 50-inch diameter drivers was 195,000 pounds, making them the heaviest engines built up to that time. They had the power to pull a 760-ton train up the long 2 percent grade at both ends of the tunnel. [HAER-data]

As long as a train was not delayed, asphyxiation was not an issue. But the locomotives were strong enough that they broke couplers on the 2% grade. This left crew stuck in the tunnel. After the third fatal accident in 1904, the Grand Trunk decided to use electric traction. GE bid a 600v DC third rail system, i.e. streetcar technology. Westinghouse proposed a 3,300v AC single-phase system and won the contract. The first electric train passed through the tunnel on Feb 20, 1908. The contract included a power house, electrification of the water pumps, new lighting for the tunnel, and power for the company buildings (depot, roundhouse, shops, and YMCA) in both Port Huron and Sarnia. Baldwin Locomotive Works helped build the six boxcab locomotives. The last steam locomotive was retired May 17, 1908. Westinghouse supervised the operation until transferring control to the St. Clair Tunnel Company on Nov 12, 1908. In May 1917, they switched to Detroit Edison and scrapped their generation equipment. Three more locomotives were bought in 1927 to help handle heavier trains. From that time on, they routinely ran four locomotives at a time and kept the ninth as a spare. In 1949, the wood ties were replaced with concrete ties and the tracks were lowered 7 inches to allow taller boxcars to use the tunnel. In 1958, an improved ventilation system was installed so that diesel could replace electric locomotives. In March 1971, they reintroduced a ferry service to handle the even taller tri-level auto carriers and 85' long automobile parts cars. Because of the growth of double-stack container cars, in the 1990s CN built a replacement 31' single-track tunnel just north of the original tunnel. [HAER-data]


Ross Gray posted 13 photos with the comment: "GTR Sarnia ON circa 1908." (source)

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1892, p7

1892, p9

1892, p11
[Each of the 13 cast segments in a ring weighed 1000 pounds. There was also a 14th "key" segment for each ring. [HAER-data]]

1892, p13

1892, p5

1892, p4

1892, p6

1892, p12
[Note the illustration of the shield in the middle.]

1892, p18, cropped

1892, p20

1892, p34

1892, p70, cropped

1892, p78, cropped

1892, p114

Toronto Railway Historical Association posted four photos with the comment:

On April 5, 1995, the first Canadian National freight train ran through the new $200 million St. Clair Tunnel between Sarnia, Ontario and Port Huron, Michigan.
The original 1891 tunnel was not able to accommodate tri-level automobile carriers or the largest double-stack containers. These cars had to be ferried across the river, causing significant delays to CN freight traffic between eastern Canada and Chicago.
The last train to pass through the old tunnel was VIA Rail and Amtrak's westbound Toronto-Chicago train, the "International."

Jeff Steele What became of the old tunnel?
Micheal Hackman Jeff Steele still there if I remember right the is fiber and phone lines still in it

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Dean Wilkins The old tunnel leaked pretty good and with no pumps running I’m quite sure it will be full of water.

Michael Wawrow commented on a post
[This appears to be a TBM head for a different tunnel.]

Michael Wawrow commented on a post
My train at London bringing Excalibor to Sarnia.
[It appears the name of the TBM was Excalibor.]

Michael Wawrow commented on a post

Brian Caswell posted
Jeremy J Schrader: Very nice way to show just how close the tunnel and river are in proximity.
Brian Caswell: Jeremy J Schrader thank you and that was the full intention of this shot!
Roger Riblett shared

Dennis DeBruler: The American side of the St. Clair Tunnel

42°57'36.4"N 82°26'00.5"W

42.960123, -82.433469

[Normally I'd provide a 3D satellite URL as a comment, but Facebook would then delete the comment as a violation of Community Standards.]

Charles Geletzke Jr. posted
Here is a shot that is not easy to get! In actuality a CN crew stalled in the Tunnel on the Port Huron, Michigan side while bringing the train over from Toronto on July 27, 2002. Since we had to walk down and relieve them, I climbed aboard, turned on the ditch lights and put the headlight on Bright, and then climbed back down and took this photo. Oh yes, it was Train 383 with the CN 2632 and 2556. What really would have been neat would have been shots of us lifting the train out of there! (C. H. Geletzke, Jr. photo)
Terry L. Hunt: 383 the perennial problem child in the tunnel. When I was RFE I was always being called to get a download because of 383 stalling or getting a knuckle.
Charles Geletzke Jr. shared

Rob Kitchen commented on Charles post
Here's the ballast train coming back from dumping ballast after rebuilding the track in July, 2019