12/02/2025
Facts i-74 Bridge
Construction & Design
-Twin Spans: The crossing consisted of two separate, nearly identical suspension bridges.
-Opening Dates: The first span (initially two-way traffic, later westbound) opened on November 18, 1935. The second span (eastbound) opened on December 22, 1959.
- Key Engineer: The bridges were designed by the renowned engineer Ralph Modjeski and his firm Modjeski and Masters.
- - Design Details: They were steel suspension bridges featuring distinctive fixed-base, flexible-type steel towers with large "X" patterns.
- Foundation: The in-river foundations (piers) were constructed using pneumatic caissons to reach bedrock below the Mississippi Riverbed.
- Operations & Traffic
Toll Bridge: Both spans operated as a toll bridge for decades. Initial tolls were 15 cents for a passenger car and 5 cents for a pedestrian.
- Tolls Abolished: The U.S. government purchased the bridges, and tolls were removed on December 31, 1969, after construction bonds were paid off.
- Interstate Routing: The bridges officially became part of the I-74 route on December 10, 1975.
- Functional Obsolescence: The original design capacity was around 48,000 vehicles per day; in its final years, it routinely carried over 80,000, making it the most traveled bridge in the Quad Cities area.
- Safety Issues: Each span had only two narrow lanes and no emergency shoulders, contributing to frequent traffic jams and safety concerns. In 2012, U.S. Transportation Secretary Ray LaHood called it "one of the worst" bridges he had ever seen.
Demolition
- Permanent Closure: The old bridges were permanently closed to traffic in November 2020 and December 2021 as the new bridge opened in stages.
- Demolition Method: The deconstruction involved a combination of piece-by-piece dismantling (to protect endangered mussel beds below) and several controlled explosions to drop the main towers and piers.
- Final Demolition: The last major implosion occurred in February 2024, concluding the removal process. A few original piers were left in place with navigation lights for historical purposes and to aid river traffic.
