Delaware Memorial Bridge: Construction & History

Instructor: Stephanie Przybylek

Stephanie has taught studio art and art history classes to audiences of all ages. She holds a master's degree in Art History.

East Coast travelers heading to Rehoboth Beach or Baltimore will probably drive across the Delaware River, perhaps on a unique twin suspension bridge. In this lesson, explore the Delaware Memorial Bridge, its history, and construction.

Connecting Delaware and New Jersey

Have you ever driven from Boston or New York City to Baltimore or Washington, DC? Did you get stuck in traffic? If so, you are not alone. Several major highways, including I-95, run through this congested area. Several large bridges also help get travelers where they need to go.

The Delaware Memorial Bridge, which connects Pennsville, New Jersey to New Castle, Delaware, is the most southern of a series of bridges that cross the Delaware River. The others are closer to Philadelphia in one of the busiest traffic corridors in the United States.

The Delaware Memorial Bridge is an unusual twin span suspension bridge. You don't see many large bridges side by side. A suspension bridge, is one on which the deck and roadway are suspended by cables attached to two tall towers. The towers support most of the weight.

View of the twin spans of the Delaware Memorial Bridge
Delaware Memorial Bridge

Operated by the Delaware River and Bay Authority (DRBA), a bi-state agency, these massive twin spans carry I - 295, an interstate highway and U. S. Route 40. They are 2,150 feet high and 10,796 feet long. Whew, that is quite a building achievement. But how did this bridge come to be built and why the two spans side-by-side?

Construction of the Delaware Memorial Bridge: First Span

Before the bridge, Delaware and Southern New Jersey were connected by ferry. But ferries carry limited numbers of cars and people, and in 1940 Delaware's General Assembly proposed studying the feasibility of building a bridge or tunnel. A tunnel turned out to be too expensive, so they focused on the bridge. But World War II intervened, and it wasn't until 1947 that the Delaware River Crossing Division was formed and construction started.

A firm known as HNTB (Howard, Needles Tammen & Bergendoff) designed the bridge. They consulted with Swiss-American engineer Othmar Ammann, famous for his work on the George Washington Bridge and the Verrazano Narrows Bridge, both near New York City. Construction began in November 1949, when sections of the steel foundation, made in a New Jersey steel yard, were towed down river on barges.

The American Bridge Company of Coraopolis, Pennsylvania was responsible for building the bridge. On the Delaware side, construction began by positioning a massive caisson in the ground and pouring concrete around it. A caisson, also called a pier foundation, is a watertight retaining structure used to form the foundations of bridge piers. It's essentially a hollow box sunk into the ground and filled with concrete. It was a massive job, and took a week of continuous concrete pouring to complete. At this time, the anchorages, massive rock or cement structures in which the bridge and its cables are grounded, were also built. The first span was made of riveted steel plates. Because it was a suspension bridge, it also required the installation of heavy cables from the tall towers to the anchorages.

Postcard view of the first span of the Delaware Memorial Bridge, ca. 1956
first span of Delaware Memorial Bridge

After the administrative buildings and tollbooths were built, the first span officially opened in 1951. It proved successful and traffic steadily increased.

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