Bridges

Benjamin Franklin Bridge

As early as 1818 a span across the Delaware River was proposed and interest continued through the 1840’s but it took introduction of automobiles to resurrect interest in a proposed Delaware River bridge.  In 1913 the City of Philadelphia formed the Penn Memorial Bridge Commission to study a plan.   A  Joint Commission for the construction of a public bridge was first legally initiated in 1914 by the New Jersey Legislature.  The effort culminated in 1919 in the passage by the legislatures of both New Jersey and Pennsylvania of uniform laws creating the Delaware River Bridge Joint Commission with full power and authority to proceed with the work. (excerpt)

http://www.lehigh.edu/library/speccoll/delaware_bridge.html

In 1926,  the time of its completion the Delaware River Bridge was considered “The World’s Greatest Suspension Bridge” (American Cable Company, Inc., 1926).  The reasons for this appellation was that its main span between the towers was 1750 feet (533.4 meters), longest of its kind in the world at that time (the total length of the bridge is 9573 feet, 2,917.86 meters), and that there are only two main cables (each 30 inches in diameter) carrying the suspended structure, a feat that the cable manufacturer American Cable Company, Inc. noted as especially worthy of recognition.  There were 25,100 miles of wire used in constructing the enormous cables.   Previous suspension bridges such as the Manhattan (main cables 20 ½ inches in diameter) or Brooklyn (main cables 15 ¾ inches in diameter) bridges had four main cables carrying the suspended structure.  The towers are 385 feet tall.  The width of the structure 128 feet (39.01 meters) was intended to accommodate two 10-foot sidewalks, a 57-foot roadway, two trolley tracks and two rapid transit tracks at the time of completion.  There is a 135 foot (41.19 meter) clearance over the center channel of the river determined by the United States War Department for Navy ships to pass unobstructed into the port of Philadelphia.  The final construction cost was $24,574,024.

2ben_frank

The bridge connected center city Philadelphia, PA with Camden, N.J. across the Delaware River.  At present it carries highways U.S. Route 30 and I-676 on seven lanes for vehicular traffic separated by concrete “zipper” barriers (can be moved to configure flow of traffic), two tracks for the PATCO Speedline (the Port Authority Transit Corporation’s Lindenwold High-Speed Line) and two pedestrian walkways.  The bridge is a toll bridge and has always been so designated.  The bridge is owned and maintained by the Delaware River Port Authority of Pennsylvania and New Jersey which was created in 1951 to adapt the bridge to the interstate highway system.  This bi-state commission oversaw the necessary interstate highway improvements to the Delaware River Bridge and in 1956 the  bridge was renamed as it was dedicated to honor Benjamin Franklin as well as  recognizing its beauty and magnificence as a span.  The bridge is now universally known as the Benjamin (Ben) Franklin Bridge.

As early as 1818 a span across the Delaware River was proposed and interest continued through the 1840’s but it took introduction of automobiles to resurrect interest in a proposed Delaware River bridge.  In 1913 the City of Philadelphia formed the Penn Memorial Bridge Commission to study a plan.   A  Joint Commission for the construction of a public bridge was first legally initiated in 1914 by the New Jersey Legislature.  The effort culminated in 1919 in the passage by the legislatures of both New Jersey and Pennsylvania of uniform laws creating the Delaware River Bridge Joint Commission with full power and authority to proceed with the work.  In September 1920, the Commission appointed the Board of Engineers composed of Ralph Modjeski, Chairman; George S. Webster and Laurence A. Ball.  Modjeski was selected over many other engineers because he had been identified or in charge of many of the greatest bridges built in the United States.  In 1921 the go ahead was given to build the bridge.  An act of Congress was passed and approved by the President granting the Delaware River Bridge Joint Commisson “the right to construct, maintain and operate a bridge and approaches thereto across the Delaware River at a point suitable to navigation at or near Green Street and South Street in Philadelphia, Pennsylvania and points approximately opposite in Camden, New Jersey.” (Carswell, p.7).  Official start of physical construction began January 6, 1922 on the Philadephia side.(Carswell, p.5).  The completion date of the bridge was determined in 1921and the recommendation date of July 4, 1926 the Sesqui-Centennial of the Declaration of Independence was established.  Because the holiday fell on a weekend to accommodate holiday traffic the bridge opened July 1, 1926 to vehicular traffic.  President Calvin Coolidge officiated at the opening.

The bridge is a wire-cable steel suspension bridge and employs with the Manhattan Bridge (another Modjeski bridge) the practical application of the “deflection theory” in its design.  Ralph Modjeski (1861-1940) was chief engineer, Leon Moisseiff was design engineer and Paul Philippe Cret was the architect.  The construction was by American Bridge Co. (deck and approaches), Bethlehem Steel Co. (towers), Keystone State Construction Co. (piers, anchorages and installation of cables) and American Cable Co. (manufactured the wire for the cables).  This bridge spawned an era of long-span suspension bridges that lasted into the late 1930’s.  The Benjamin Franklin Bridge (Delaware River Bridge) was the first of four primary bridges to eventually cross the Delaware River from the City of Philadelphia to Camden and southern New Jersey.

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