I-74 Bridge

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Interstate 74 Bridge
I-74 Bridge.jpg
The Interstate 74 bridge as seen from the Iowa side of the Mississippi River
Coordinates41°31′12″N 90°30′48″W / 41.52000°N 90.51333°W / 41.52000; -90.51333
Carries4 lanes of I‑74 / US 6
CrossesMississippi River
LocaleBettendorf, Iowa and Moline, Illinois
Official nameIowa-Illinois Memorial Bridge
DesignTwin suspension bridges
Total length3,372 feet (1,028 m)[1]
Width27 feet (8 m)[1]
Longest span227 metres (745 ft)
OpenedNovember 1935 (northbound)
December 1959 (southbound)
Daily traffic80,000[2]

The Interstate 74 Bridge, officially known as the Iowa-Illinois Memorial Bridge, and often called The Twin Bridges, or the I-74 Bridge, is a pair of suspension bridges that carry Interstate 74 across the Mississippi River and connect Bettendorf, Iowa and Moline, Illinois. It is located near the geographic center of the Quad Cities.

The bridge was designed by engineer Ralph Modjeski. The first span opened in 1935 as a toll bridge. In 1959, an identical twin span was added to satisfy increased traffic. The twin spans were upgraded to carry interstate traffic in the mid-1970s. Built for a daily crossing of 48,000 vehicles, the daily average is 80,000,[2] making it by far the most traveled bridge in the Quad Cities. Both the Interstate 80 and 280 bridges are up to Interstate standards, while the Interstate 74 Bridge is functionally obsolete and was not built to Interstate standards, as it has two narrow lanes, no shoulder, and a 50 mile-per-hour (80 km/h) speed limit.

I-74 bridge replacement[edit]

The I-74 Corridor Study was completed to study replacing the bridge with a larger one with 4 lanes in each direction. The study claimed that the I-74 Bridge project would spur economic growth, create construction jobs, reduce traffic backups, and improve air quality.

Funding for the construction of the new bridge has been earmarked for $22 million in 2017 and $50 million in 2018. Former Illinois Governor Pat Quinn said the state is committed to bridge improvements to help traffic flow and "boost economic growth in the region".

As of 2012, the Illinois Department of Transportation also budgeted more than $34 million for engineering, design and land acquisition for the new bridge. The conceptual design of the arch bridge was completed by Boston-based bridge designer Miguel Rosales from Rosales + Partners. Final design is being completed by Modjeski and Masters in association with Alfred Benesch & Company. The portion of the bridge spanning the Mississippi River is estimated at more than $700 million, while the project as a whole, including all approach routes and connectors, is estimated at more than $1.3 billion.

While on a tour at the base of the bridge in Bettendorf in May 2012, U.S. Transportation Secretary Ray LaHood said that, in comparison with other bridges that he has seen in other states, the current I-74 Bridge is one of the worst he's seen.[3][4]

The new bridge will be just upstream of the existing bridge and will be a basket-handle, true-arch twin bridge with four lanes in each direction and pedestrian access. [5] A ground-breaking ceremony for the new bridge, which is expected to be complete in 2020, was held on June 26, 2017.[6] The existing I-74 bridge is scheduled to be imploded in 2020 or 2021.

See also[edit]


  1. ^ a b "Bridges: Iowa, Illinois order safety inspections". Quad City Times. Retrieved 2007-12-19.
  2. ^ a b http://www.helmgroup.com/documents/HelmGroup-Fall2011_CS5.pdf[permanent dead link]
  3. ^ Funding Back For I-74 Bridge - KWQC-TV6 News and Weather For The Quad Cities Archived 2012-05-17 at the Wayback Machine.
  4. ^ "Archived copy". Archived from the original on 2012-06-25. Retrieved 2012-05-27.
  5. ^ [1]
  6. ^ [2]

External links[edit]