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Songo Lock Bridge

Songo Lock Bridge

Primary Photographer(s): Nathan Holth

Bridge Documented: June 15, 2012

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Key Facts

Facility Carried / Feature Intersected
State Park Road Over Songo River
Rural: Cumberland County, Maine: United States
Construction Date and Builder / Engineer
1901 By Builder/Contractor: American Bridge Company of New York, New York

Technical Facts

Rehabilitation Date
Main Span Length
56 Feet (17.1 Meters)
Structure Length
60 Feet (18.3 Meters)
Roadway Width
13.5 Feet (4.11 Meters)
1 Main Span(s)
NBI Number

Historic Significance Rating (HSR)
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Bridge Documentation

View Archived National Bridge Inventory Report - Has Additional Details and Evaluation

This bridge is a national rarity: a hand-turned swing bridge that still operates for boats! This bridge is a rare chance to see how many movable bridges once operated. Unfortunately, floods had clogged up the center pier when HistoricBridges.org documented the bridge, so the span was not operating. However, there are YouTube videos showing the bridge opening and closing that can be viewed.

News articles and the National Bridge Inventory list a 1926 construction date for the bridge. However, the plaque on the bridge lists a 1901 construction date and lists the American Bridge Company as builder. It is not known where the 1926 construction date comes from. It could be an error, or it might indicate that this span was relocated to this site in 1926, or the bridge might have been rehabilitated in 1926. As an American Bridge Company bridge built in 1901, it is among the first examples in the country of a bridge built by the company which was formed in April, 1900 from numerous smaller bridge companies. American Bridge Company went on to become one of the most important bridge builders of the 20th Century. With a 1901 construction date, the bridge is also a very early surviving example of a movable highway bridge. With a 60 foot overall length, and a 13.5 foot roadway, this is truly a tiny movable bridge. It may be among the shortest swing bridges in the country. A modern, non-historic swing bridge in Alanson, Michigan, has an overall length of 64 feet and is advertised as the "shortest swing bridge in the world." While the grandiose claim of Alanson is questionable, even if  the length of the Songo Lock Bridge wasn't listed as shorter, this serves to illustrate that certainly, the Songo Lock Bridge is a short swing bridge. Perhaps a combination of the Songo Lock Bridge's early construction date, small size, and hand-operated design, the bridge is one of the technologically simplest movable bridges to be encountered. A simple lever is pulled by hand to lift a rod out of the abutment, which unlocks the bridge for movement. A different sort of rod is inserted into a hole in the deck, which connects to a simple gear system under the bridge. The operator simply walks the road around the hole in the deck which operates the bridge.

Overall, this bridge appears to be maintained in excellent condition, suggesting there is a commitment to the preservation of this rare historic bridge.

Information and Findings From Maine's Historic Bridge Inventory

Discussion of Bridge

"The Songo Lock swing span bridge dates to 1901, but it was originally located at Naples Bay. It was moved to Songo Lock in 1926 when the Naples Bay crossing was upgraded. It is the oldest identified, operable swing span bridge in the state. The movable span is a built up thru girder-floorbeam. The bridge is operated manually during the summer boating season. The bridge is 250' upstream from operable and National Register-listed Songo Lock. The bridge is judged to have average preservation priority. It is the oldest of five remaining girder-floorbeam swing span bridges in the state, and it has been moved once. There are 8 swing span bridges in Maine."

Bridge Considered Historic By Survey: Yes


Photo Galleries and Videos: Songo Lock Bridge

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