Dare to witness a feat of engineering. It stands as a testament to Chicago’s industrial might. We are standing before the St. Charles Air Line Bridge. This bridge is not just steel and concrete. It’s a symbol of innovation and connection.
The St. Charles Air Line Bridge was completed in 1919. Joseph B. Strauss designed it. He was an acclaimed engineer. He is known for his work on movable bridges. The St. Charles Air Line Bridge is a bascule bridge. It’s a “heel trunnion” design. Strauss developed this design for long spans.
When finished, the St. Charles Air Line Bridge was the world’s longest and heaviest single-leaf bridge. Imagine that. A single leaf stretching across the river. The bridge is made of heavily bolted steel girders. Massive reinforced-concrete counterweights balance the span.
Originally, the St. Charles Air Line Bridge was longer. Its leaf measured 260 feet. That’s a record-setting length for the time. In 1930, the river was straightened. The bridge was moved and shortened to its current 220-foot length. This relocation was planned from the start.
Four railroad companies shared the costs to build the St. Charles Air Line Bridge. They also shared operating costs equally. This shows early cooperation between railroad companies. Today, the bridge still serves freight and passenger trains. It’s still operable.
The St. Charles Air Line Bridge has a counterweight. It is not fixed. It moves independently. This helps the bridge operate smoothly. The bridge still opens for boats. This is especially true during spring and fall. It allows access to a boat storage facility.
Interestingly, the St. Charles Air Line Bridge made a movie appearance. This happened on June 23, 1920. That’s just a year after it was completed.
Some people think the St. Charles Air Line Bridge is not beautiful. They see it as a remnant of a long-gone industrial era. They feel it doesn’t fit in a financial-centered city. Others disagree. They appreciate the contrast between modern skyscrapers and historic structures. This contrast defines Chicago. It shows a timeline of the city’s development. The industrial past helped Chicago become the great city it is today.
The St. Charles Air Line Bridge has been designated a Chicago Landmark. This protects it from demolition. The city recognizes its importance. It is a worthwhile part of Chicago’s history.
Look closely at the St. Charles Air Line Bridge. You’ll see a plaque. It reads “Strauss Trunnion Bascule Bridge. Patented. Built 1917 for St. Charles Air Line. Fabricated by American Bridge Co.” Another plaque says, “Erected by The Ferro Construction Co. Chicago.”
The St. Charles Air Line Bridge connects us to Chicago’s past. It reminds us of the city’s industrial roots. It stands as a symbol of innovation and cooperation. It’s a vital part of Chicago’s landscape.