Tuesday, July 26, 2016

Portage Lake Lift Bridge between Houghton and Hancock, MI

(Bridge Hunter, Historic Bridges, SatelliteStreetview, Google Photo)

Wikipedia, put in the Public Domain by Justin Murawski
The double-deck span can support road traffic on both levels. The lower deck also used to have tracks to support the railroads that originally built it --- Copper Range (1906 and 1920 maps) and Duluth, South Shore & Atlantic Railway. In 1961 it became part of  Soo Line, which became Wisconsin Central in 1987. But railroad traffic stopped in 1982. Looking at a railroad map, there used to be a lot of routes and mining shafts on the peninsula. ALL of the routes are now abandoned. By the time of the abandonments, all the routes were owned by SOO (Minneapolis, St Paul & Sault Ste Marie)

Below shows the span raised high enough to pass a boat.

Wikipedia, Chris857 Photo, CC BY-SA
Below is an older photo when the tracks were still intact showing the span lowered to allow a train to cross.

By railfan 44 - https://www.flickr.com/photos/129679309@N05/27482497891/, Public Domain, Link
Copper Country Limited updated
Alex Sansone Lot of power for a small train


Because the railroads ran close to the shore, they were low. When lowered for rail traffic, not even a speedboat could pass underneath. That is why it is important that the bridge is normally at the intermediate level during navigation season. But there is no canal traffic during the winter so the bridge is lowered so that snowmobiles and skiers using the old railroad right-of-ways as trails can also use this bridge.

The original bridge was a wooden swing bridge completed in 1875. This was replaced by a steel swing bridge in 1901. In 1959 the swing bridge was replaced by this bridge. It has a 100' clearance when fully raised. [Wikipedia] When built, it was the heaviest lift bridge constructed. [Posting]

A video of it being raised for a ferry. "It's hard to catch the bridge in action anymore but I caught it last fall when the twice a week ferry to Isle Royale left." (source)



These screenshots below are from a video of the construction of the lift bridge that replaced a swing bridge that had just 5-feet of clearance and took a long time to open and close. So traffic backups through the two towns were common. The bridge has two decks. Originally the upper deck of the approaches carried vehicles and the lower deck carried railroads. Normally, the lower deck of the lift span is aligned with the vehicle deck of the approach spans to provide a 32-foot clearance that allows most pleasure craft and fishing boats to pass without stopping traffic as depicted by the first screenshot. The second screenshot shows the lift span lowered so that both vehicle and railroad traffic can cross.

 Screenshot
Screenshot
The full height provides a clearance of 100 feet. This video of the bridge going up and down is made from three perspectives: from a boat, from the shore, and from a pedestrian crossing.

Looking at a railroad map, there used to be a lot of routes and mining shafts on the peninsula. ALL of the routes are now abandoned. By the time of the abandonments, all the routes were owned by SOO (Minneapolis, St Paul & Sault Ste Marie)

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