Penobscot Narrows Bridge
Encyclopedia
The Penobscot Narrows Bridge is a cable-stayed
bridge
over the Penobscot River
near Bucksport, Maine
. It replaced the Waldo–Hancock Bridge, built in 1931. The new bridge is 2120 feet (646 m) long. It is one of three bridges in the U.S. (the others being Zakim Bridge in Boston, MA, and Veterans' Glass City Skyway in Toledo, OH) constructed recently to utilize a cradle system that carries the strands within the stays from bridge deck to bridge deck, as a continuous element, eliminating anchorages in the pylons. Each epoxy-coated steel strand is carried inside the cradle in a one-inch steel tube. Each strand acts independently, allowing for removal, inspection and replacement of individual strands. The cable-stay system was designed with a system that uses pressurized nitrogen gas
to defend against corrosion. Additionally, in June 2007, six reference strands within three stays were replaced with carbon fiber strands - a first in the U.S. Monitoring on the strands will evaluate this material for future use in bridge designs. These engineering innovations helped the bridge appear in the December 2006 edition of Popular Science
as one of the 100 best innovations of the year. The total project cost was $85 million. The bridge was designed as an emergency replacement for the Waldo-Hancock Bridge and from conception to completion, just 42 months elapsed. A unique project delivery method, referred to as 'owner facilitated design/build' partnered Maine DOT with FIGG as the designer and Cianbro/Reed & Reed LLC as the contractor. The elevator system in the tower was installed by Stanley Elevator Company Inc.
and Bay
. The tower is accessible through the Fort Knox site and as of August 2009 charges a $7 fee for adult nonresidents and $5 for adult residents. The fee for children 5-11 is $3, and children 4 and under are admitted for free. These prices include admission to both the Observatory and the Fort Knox site.
The Penobscot Narrows Observatory opened to the general public on Saturday, May 19, 2007. It is open at the same times of the year as Fort Knox (May 1 to October 31).
Cable-stayed bridge
A cable-stayed bridge is a bridge that consists of one or more columns , with cables supporting the bridge deck....
bridge
Bridge
A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
over the Penobscot River
Penobscot River
The Penobscot River is a river in the U.S. state of Maine. Including the river's West Branch and South Branch increases the Penobscot's length to , making it the second longest river system in Maine and the longest entirely in the state. Its drainage basin contains .It arises from four branches...
near Bucksport, Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
. It replaced the Waldo–Hancock Bridge, built in 1931. The new bridge is 2120 feet (646 m) long. It is one of three bridges in the U.S. (the others being Zakim Bridge in Boston, MA, and Veterans' Glass City Skyway in Toledo, OH) constructed recently to utilize a cradle system that carries the strands within the stays from bridge deck to bridge deck, as a continuous element, eliminating anchorages in the pylons. Each epoxy-coated steel strand is carried inside the cradle in a one-inch steel tube. Each strand acts independently, allowing for removal, inspection and replacement of individual strands. The cable-stay system was designed with a system that uses pressurized nitrogen gas
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
to defend against corrosion. Additionally, in June 2007, six reference strands within three stays were replaced with carbon fiber strands - a first in the U.S. Monitoring on the strands will evaluate this material for future use in bridge designs. These engineering innovations helped the bridge appear in the December 2006 edition of Popular Science
Popular Science
Popular Science is an American monthly magazine founded in 1872 carrying articles for the general reader on science and technology subjects. Popular Science has won over 58 awards, including the ASME awards for its journalistic excellence in both 2003 and 2004...
as one of the 100 best innovations of the year. The total project cost was $85 million. The bridge was designed as an emergency replacement for the Waldo-Hancock Bridge and from conception to completion, just 42 months elapsed. A unique project delivery method, referred to as 'owner facilitated design/build' partnered Maine DOT with FIGG as the designer and Cianbro/Reed & Reed LLC as the contractor. The elevator system in the tower was installed by Stanley Elevator Company Inc.
Observation Tower
The Penobscot Bridge site also is home to the Penobscot Narrows Observatory, the first bridge observation tower in the United States and the tallest public bridge observatory in the world. The tower reaches 420 feet (128 m) into the air and allows visitors to view the bridge, the nearby Fort Knox State Historic Site and the Penobscot RiverPenobscot River
The Penobscot River is a river in the U.S. state of Maine. Including the river's West Branch and South Branch increases the Penobscot's length to , making it the second longest river system in Maine and the longest entirely in the state. Its drainage basin contains .It arises from four branches...
and Bay
Penobscot Bay
Penobscot Bay originates from the mouth of Maine's Penobscot River. There are many islands in this bay, and on them, some of the country's most well-known summer colonies. The bay served as portal for the one time "lumber capital of the world," namely; the city of Bangor...
. The tower is accessible through the Fort Knox site and as of August 2009 charges a $7 fee for adult nonresidents and $5 for adult residents. The fee for children 5-11 is $3, and children 4 and under are admitted for free. These prices include admission to both the Observatory and the Fort Knox site.
The Penobscot Narrows Observatory opened to the general public on Saturday, May 19, 2007. It is open at the same times of the year as Fort Knox (May 1 to October 31).