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Emergency Swing Dam

   
                  


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Bridge Documented: May 14, 2006
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Key Facts
Bridge Name Facility Carried / Feature Intersected Location Structure Type Construction Date and Builder/Engineer
Emergency Swing Dam
Maintenance Walkway Over Sault Canal (St. Marys River) Sault Ste. Marie: Algoma District, Ontario Metal Pin-Connected Baltimore Through Truss, Movable: Swing (Center Pier) 1898 By Builder/Contractor: Dominion Bridge Company of Montréal, Québec
Technical Facts
Main Spans
1

Historic Significance Rating (HSR)

Primary Photographer(s): Nathan Holth

This Emergency Swing Dam has global significance as the last remaining structure of its kind in the world, a bridge-like dam that can swing out over the water, and lower wickets and shutters down into the water to reduce the flow of water. Although this bridge has only been called into service once, the bridge proved that one time to be a valuable asset. If a boat breaks the locks and releases torrents of water, this dam allows for a temporary slowing of that water flow so that the locks can be repaired and closed once again.

This is not a bridge in the sense that it was not built to facilitate the crossing of something. However, that is where the dissociation with the word "bridge" ends. This structure is in terms of design a swing truss bridge, and for that reason it appears on this website as one of the finest and most unusual bridge structures in Canada. It was built in 1896 by the Dominion Bridge Company, which was based in Lachine, which is part of Montreal, Quebec. This company also built the nearby fixed spans of the International Railroad Bridge, according to builder plaques on that structure.

The Emergency Swing Dam features a Baltimore style truss configuration. Most connections are pinned, although some are riveted. Compression members on the bridge are built-up with substantial v-lacing and lattice used. There are an unusually large number of different steel mill stamps on this bridge including some from the U.K. There are Carnegie stamps, Burbach stamps, Consett stamps, and finally a mark reading "A.H.A.V. 1891" to me. The 1891 might refer to some sort of patent date, or when the iron was actually rolled at the mill. The bridge itself was erected in 1896.

The bridge retains a high degree of historic integrity, with some exceptions. The deck beams are huge on this bridge and are likely not original. Nor is machinery house, which houses the motor and other machinery. Also, some floor beams have steel welded to them and to some rollers below that handle the chain. This apparently was to strengthen the rollers. There is a weird i-beam that runs the length of the east side of the bridge and is attached to a weird arrangement of bracing in front of the portal bracing. All of this is riveted, but it does not look like it fits in although it appears to be original anyway. It is definitely old, and is visible in a 1909 historic photograph. The bridge has been maintained very well, and there is no major structural deterioration. It is good to see this wonderful structure being maintained for future generations. The informative sign near the bridge shows that Ontario is indeed recognizing the historic nature of it and wants to help educate the public about this bridges fascinating history and operation.

This bridge was only used once, way back in June 9, 1909.

The Accident at the Canadian Canal, Sault Ste. Marie, Ontario, 1909

There was a major accident on June 9, 1909 at the Sault Canal. Downbound from Lake Superior, the Canadian passenger vessel Assiniboia was waiting in the lock at the Sault to be lowered to the Lake Huron level of the St. Marys River. Behind the Assiniboia, the Pittsburg Steamship Company's steamer Crescent City was just entering the lock. Captain Frank Rice was asked to lock down with the Canadian Pacific passenger vessel Assiniboia.

The Canadian canal was fourteen years old in September 1909, having been officially opened on September 7, 1895. The lock was built between 1888 and 1895.

On June 9, 1909, the Perry G. Walker, owned by the Gilchrist Transportation Co. of Cleveland, Ohio, proceeded up the St. Marys River intent on locking through the American canal. Captain Moshier was impatient. He could see several vessels ahead of him also awaiting upbound passage. He began moving his vessel towards the Canadian canal, intent on a quick lockage. The vessel continued up the lower approach. The master, ignoring previous instructions to moor at the southeast pier to await passage, kept moving upwards.

Finally the order to reverse engines was sounded. The Captain made an effort to reverse the engine but there was a misunderstanding of the signals and the engineer did not reverse the engine. It was too late to stop the vessel which was moving at eight or nine kilometres per hour and was within 70 metres of the lock gates.

The Walker struck the south main gate, forcing it back and allowing the force of water to push the north main gate over. The rush of water threw the Walker back, her bow swinging to the south. The Assiniboia was carried down against the Walker, striking the starboard side.

The Crescent City dropped onto the upper wall carrying away the timber work. Leaving the lock, she surged ahead. Suddenly the Assiniboia dropped her anchor, swinging her stern over towards the north pier and the Walker. Immediately Captain Rice called for full speed astern. Slowly the Crescent City responded, swinging her stern to starboard at the last moment. She struck her starboard beam on the Assiniboia and avoided the Perry Walker.

Either the Assiniboia or the Crescent City in their downward drop struck the south main gate, breaking it diagonally in two. Surprisingly no one was hurt during this accident.

With the gates being swept away, it was necessary to bring the Emergency Swing Bridge Dam into operation. This was the first time the structure was required in an emergency situation. The emergency swing bridge dam stopped the flood of water, allowing repairs to be done on the canal and the lock.

There was extensive damage to the valves, the wooden gates, the stonework and the timber on the lock floor. All of the repair work was completed by June 21, 1909, and the canal was reopened.

The canal had been closed for repairs for a total of twelve days. Considering the damage done, the repairs were made in a short period of time thanks to the successful operation of the Emergency Swing Bridge Dam.

Above: View of the damage to the locks.

Above: View of the swing dam in operation.

Excerpts taken from:

Harrison, R. "The Break at the Canadian Canal, Sault Ste. Marie, Ontario, 1909". Inland Seas. Volume 34, No. 2, Summer, 1979. pgs 104-109.

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Photos and Videos: Emergency Swing Dam

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For the best visual immersion and full detail, or for use as a desktop background, this gallery presents selected overview and detail photos for this bridge in the original digital camera resolution. For the best visual immersion and full detail, or for use as a desktop background, this gallery presents the photos for this bridge in the original digital camera resolution.
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A collection of overview photos that show the bridge as a whole and general areas of the bridge. View the photos for this bridge in a reduced size which is useful for mobile/smartphone users, modem (dial-up) users, or those who do not wish to wait for the longer download times of the full-size photos. Alternatively, view this photo gallery using a popup slideshow viewer (great for mobile users) by clicking the link below.
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These photos are mainly to document the design, construction, and materials of the bridge. They provide a detailed look at how this bridge was built, and what was used to build it. View the photos for this bridge in a reduced size which is useful for mobile/smartphone users, modem (dial-up) users, or those who do not wish to wait for the longer download times of the full-size photos. Alternatively, view this photo gallery using a popup slideshow viewer (great for mobile users) by clicking the link below.
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These photos show the various parts that worked to move the bridge, and also to create the dam. View the photos for this bridge in a reduced size which is useful for mobile/smartphone users, modem (dial-up) users, or those who do not wish to wait for the longer download times of the full-size photos. Alternatively, view this photo gallery using a popup slideshow viewer (great for mobile users) by clicking the link below.
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